* [PATCH v5 00/21] KVM: Extend Eager Page Splitting to the shadow MMU
@ 2022-05-13 20:27 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:27 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
This series extends KVM's Eager Page Splitting to also split huge pages
mapped by the shadow MMU, specifically **nested MMUs**.
For background on Eager Page Splitting, see:
- Proposal: https://lore.kernel.org/kvm/CALzav=dV_U4r1K9oDq4esb4mpBQDQ2ROQ5zH5wV3KpOaZrRW-A@mail.gmail.com/
- TDP MMU support: https://lore.kernel.org/kvm/20220119230739.2234394-1-dmatlack@google.com/
Splitting huge pages mapped by the shadow MMU is more complicated than
the TDP MMU, but it is also more important for performance as the shadow
MMU handles huge page write-protection faults under the write lock. See
the Performance section for more details.
The extra complexity of splitting huge pages mapped by the shadow MMU
comes from a few places:
(1) The shadow MMU has a limit on the number of shadow pages that are
allowed to be allocated. So, as a policy, Eager Page Splitting
refuses to split if there are KVM_MIN_FREE_MMU_PAGES or fewer
pages available.
(2) Huge pages may be mapped by indirect shadow pages which may have access
permission constraints from the guest (unlike the TDP MMU which is
ACC_ALL by default).
(3) Splitting a huge page may end up re-using an existing lower level
shadow page tables. This is unlike the TDP MMU which always allocates
new shadow page tables when splitting.
(4) When installing the lower level SPTEs, they must be added to the
rmap which may require allocating additional pte_list_desc structs.
In Google's internal implementation of Eager Page Splitting, we do not
handle cases (3) and (4), and intstead opts to skip splitting entirely
(case 3) or only partially splitting (case 4). This series handles the
additional cases, which requires an additional 4KiB of memory per VM to
store the extra pte_list_desc cache. However it does also avoids the need
for TLB flushes in most cases and allows KVM to split more pages mapped
by shadow paging.
The bulk of this series is just refactoring the existing MMU code in
preparation for splitting, specifically to make it possible to operate
on the MMU outside of a vCPU context.
Motivation
----------
During dirty logging, VMs using the shadow MMU suffer from:
(1) Write-protection faults on huge pages that take the MMU lock to
unmap the huge page, map a 4KiB page, and update the dirty log.
(2) Non-present faults caused by (1) that take the MMU lock to map in
the missing page.
(3) Write-protection faults on 4KiB pages that take the MMU lock to
make the page writable and update the dirty log. [Note: These faults
only take the MMU lock during shadow paging.]
The lock contention from (1), (2) and (3) can severely degrade
application performance to the point of failure. Eager page splitting
eliminates (1) by moving the splitting of huge pages off the vCPU
threads onto the thread invoking VM-ioctls to configure dirty logging,
and eliminates (2) by fully splitting each huge page into its
constituent small pages. (3) is still a concern for shadow paging
workloads (e.g. nested virtualization) but is not addressed by this
series.
Splitting in the VM-ioctl thread is useful because it can run in the
background without interrupting vCPU execution. However, it does take
the MMU lock so it may introduce some extra contention if vCPUs are
hammering the MMU lock. This is offset by the fact that eager page
splitting drops the MMU lock after splitting each SPTE if there is any
contention, and the fact that eager page splitting is reducing the MMU
lock contention from (1) and (2) above. Even workloads that only write
to 5% of their memory see massive MMU lock contention reduction during
dirty logging thanks to Eager Page Splitting (see Performance data
below).
A downside of Eager Page Splitting is that it splits all huge pages,
which may include ranges of memory that are never written to by the
guest and thus could theoretically stay huge. Workloads that write to
only a fraction of their memory may see higher TLB miss costs with Eager
Page Splitting enabled. However, that is secondary to the application
failure that otherwise may occur without Eager Page Splitting.
Further work is necessary to improve the TLB miss performance for
read-heavy workoads, such as dirty logging at 2M instead of 4K.
Performance
-----------
To measure the performance impact of Eager Page Splitting I ran
dirty_log_perf_test with support for a new flag, -n, that causes each vCPU
thread to run in L2 instead of L1. This support will be sent out in a
separate series.
To measure the imapct of customer performance, we can look at the time
it takes all vCPUs to dirty memory after dirty logging has been enabled.
Without Eager Page Splitting enabled, such dirtying must take faults to
split huge pages and bottleneck on the MMU lock.
For write-heavy workloads, there is not as much benefit since nested MMUs
still have to take the write-lock when resolving 4K write-protection
faults (case (3) in the Motivation section). But ready-heavy workloads
greatly benefit.
| Config: tdp_mmu=Y, nested, 100% writes |
| Iteration 1 dirty memory time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.367445635s | 0.359880160s |
4 | 0.503976497s | 0.418760595s |
8 | 1.328792652s | 1.442455382s |
16 | 4.609457301s | 3.649754574s |
32 | 8.751328485s | 7.659014140s |
64 | 20.438482174s | 17.890019577s |
| Config: tdp_mmu=Y, nested, 50% writes |
| Iteration 1 dirty memory time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.374082549s | 0.189881327s |
4 | 0.498175012s | 0.216221200s |
8 | 1.848155856s | 0.525316794s |
16 | 4.387725630s | 1.844867390s |
32 | 9.153260046s | 4.061645844s |
64 | 20.077600588s | 8.825413269s |
| Config: tdp_mmu=Y, nested, 5% writes |
| Iteration 1 dirty memory time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.386395635s | 0.023315599s |
4 | 0.495352933s | 0.024971794s |
8 | 1.568730321s | 0.052010563s |
16 | 4.258323166s | 0.174402708s |
32 | 9.260176347s | 0.377929203s |
64 | 19.861473882s | 0.905998574s |
Eager Page Splitting does increase the time it takes to enable dirty
logging when not using initially-all-set, since that's when KVM splits
huge pages. However, this runs in parallel with vCPU execution and drops
the MMU lock whenever there is contention.
| Config: tdp_mmu=Y, nested, 100% writes |
| Enabling dirty logging time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.001330088s | 0.018624938s |
4 | 0.002763111s | 0.037247815s |
8 | 0.005220762s | 0.074637543s |
16 | 0.010381925s | 0.149096917s |
32 | 0.022109466s | 0.307983859s |
64 | 0.085547182s | 0.854228170s |
Similarly, Eager Page Splitting increases the time it takes to clear the
dirty log for when using initially-all-set. The first time userspace
clears the dirty log, KVM will split huge pages:
| Config: tdp_mmu=Y, nested, 100% writes initially-all-set |
| Iteration 1 clear dirty log time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.001947098s | 0.019836052s |
4 | 0.003817996s | 0.039574178s |
8 | 0.007673616s | 0.079118964s |
16 | 0.015733003s | 0.158006697s |
32 | 0.031728367s | 0.330793049s |
64 | 0.108699714s | 0.891762988s |
Subsequent calls to clear the dirty log incur almost no additional cost
since KVM can very quickly determine there are no more huge pages to
split via the RMAP. This is unlike the TDP MMU which must re-traverse
the entire page table to check for huge pages.
| Config: tdp_mmu=Y, nested, 100% writes initially-all-set |
| Iteration 2 clear dirty log time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.009585296s | 0.009931437s |
4 | 0.019188984s | 0.019842738s |
8 | 0.038568630s | 0.039951832s |
16 | 0.077188525s | 0.079536780s |
32 | 0.156728329s | 0.163612725s |
64 | 0.418679324s | 0.337336844s |
Testing
-------
- Ran all kvm-unit-tests and KVM selftests.
- Booted a 32-bit non-PAE kernel with shadow paging to verify the
quadrant change.
- Ran dirty_log_perf_test with support for a new flag, -n, that causes
each vCPU thread to run in L2 instead of L1. This support will be
sent out in a separate series.
- Tested VM live migration with nested MMUs and huge pages. The live
migration setup consisted of an 8 vCPU 8 GiB VM running on an Intel
Cascade Lake host and backed by 1GiB HugeTLBFS memory. The VM was
running Debian 10. Inside a VM was a 6 vCPU 4Gib nested VM also
Debian 10 and backed by 2M HugeTLBFS. Inside the nested VM ran a
workload that aggressively accessed memory across 6 threads.
Tracepoints during the migration confirmes eager page splitting
occurred, both for the direct TDP MMU mappings, and the nested MMU
mappings.
Version Log
-----------
v5:
- Rebase on top of latest kvm/queue.
- Collected R-b tags from Sean and Lai.
- Add another patch to stop passing non-zero quadrant [Sean]
- Drop vcpu_or_null and __kvm_sync_page() [Sean]
- Formatting and wording changes [Sean]
- Pass role instead of sp when making huge split SPTEs [Sean]
- Fix riscv compilation error [kernel test robot]
- Document split caches protected by slots_lock [Lai]
v4:
- Limit eager page splitting to nested MMUs [Sean]
- Use memory caches for SP allocation [Sean]
- Use kvm_mmu_get_page() with NULL vCPU for EPS [Sean]
- Use u64 instead of bit field for shadow translation entry [Sean]
- Add Sean's R-b to "Use a bool" patch.
- Fix printf warning in "Cache access bits" patch.
- Fix asymmentrical pr_err_ratelimit() + WARN() [Sean]
- Drop unnecessary unsync check for huge pages [Sean]
- Eliminate use of we in comments and change logs [Sean]
- Allocate objects arrays dynamically [Ben]
v3: https://lore.kernel.org/kvm/20220401175554.1931568-1-dmatlack@google.com/
- Add R-b tags from Peter.
- Explain direct SPs in indirect MMUs in commit message [Peter]
- Change BUG_ON() to WARN_ON_ONCE() in quadrant calculation [me]
- Eliminate unnecessary gotos [Peter]
- Drop mmu_alloc_pte_list_desc() [Peter]
- Also update access cache in mmu_set_spte() if was_rmapped [Peter]
- Fix number of gfn bits in shadowed_translation cache [Peter]
- Pass sp to make_huge_page_split_spte() to derive level and exec [me]
- Eliminate flush var in kvm_rmap_zap_collapsible_sptes() [Peter]
- Drop NULL pte_list_desc cache fallback [Peter]
- Fix get_access to return sp->role.access. [me]
- Re-use split cache across calls to CLEAR_DIRTY_LOG for better perf [me]
- Top-up the split cache outside of the MMU lock when possible [me]
- Refactor prepare_to_split_huge_page() into try_split_huge_page() [me]
- Collapse PATCH 20, 23, and 24 avoid intermediate complexity [Peter]
- Update the RISC-V function stage2_ioremap() [Anup]
v2: https://lore.kernel.org/kvm/20220311002528.2230172-1-dmatlack@google.com/
- Add performance data for workloads that mix reads and writes [Peter]
- Collect R-b tags from Ben and Sean.
- Fix quadrant calculation when deriving role from parent [Sean]
- Tweak new shadow page function names [Sean]
- Move set_page_private() to allocation functions [Ben]
- Only zap collapsible SPTEs up to MAX_LEVEL-1 [Ben]
- Always top-up pte_list_desc cache to reduce complexity [Ben]
- Require mmu cache capacity field to be initialized and add WARN()
to reduce chance of programmer error [Marc]
- Fix up kvm_mmu_memory_cache struct initialization in arm64 [Marc]
v1: https://lore.kernel.org/kvm/20220203010051.2813563-1-dmatlack@google.com/
David Matlack (21):
KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs
KVM: x86/mmu: Use a bool for direct
KVM: x86/mmu: Derive shadow MMU page role from parent
KVM: x86/mmu: Always pass 0 for @quadrant when gptes are 8 bytes
KVM: x86/mmu: Decompose kvm_mmu_get_page() into separate functions
KVM: x86/mmu: Consolidate shadow page allocation and initialization
KVM: x86/mmu: Rename shadow MMU functions that deal with shadow pages
KVM: x86/mmu: Move guest PT write-protection to account_shadowed()
KVM: x86/mmu: Pass memory caches to allocate SPs separately
KVM: x86/mmu: Replace vcpu with kvm in kvm_mmu_alloc_shadow_page()
KVM: x86/mmu: Pass kvm pointer separately from vcpu to
kvm_mmu_find_shadow_page()
KVM: x86/mmu: Allow NULL @vcpu in kvm_mmu_find_shadow_page()
KVM: x86/mmu: Pass const memslot to rmap_add()
KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu
KVM: x86/mmu: Update page stats in __rmap_add()
KVM: x86/mmu: Cache the access bits of shadowed translations
KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU
KVM: x86/mmu: Zap collapsible SPTEs in shadow MMU at all possible
levels
KVM: x86/mmu: Refactor drop_large_spte()
KVM: Allow for different capacities in kvm_mmu_memory_cache structs
KVM: x86/mmu: Extend Eager Page Splitting to nested MMUs
.../admin-guide/kernel-parameters.txt | 3 +-
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/mmu.c | 5 +-
arch/mips/kvm/mips.c | 2 +
arch/riscv/kvm/mmu.c | 8 +-
arch/riscv/kvm/vcpu.c | 1 +
arch/x86/include/asm/kvm_host.h | 26 +-
arch/x86/kvm/mmu/mmu.c | 704 ++++++++++++++----
arch/x86/kvm/mmu/mmu_internal.h | 17 +-
arch/x86/kvm/mmu/paging_tmpl.h | 17 +-
arch/x86/kvm/mmu/spte.c | 16 +-
arch/x86/kvm/mmu/spte.h | 2 +-
arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
arch/x86/kvm/x86.c | 6 +
include/linux/kvm_types.h | 9 +-
virt/kvm/kvm_main.c | 20 +-
16 files changed, 671 insertions(+), 168 deletions(-)
base-commit: a3808d88461270c71d3fece5e51cc486ecdac7d0
--
2.36.0.550.gb090851708-goog
^ permalink raw reply [flat|nested] 60+ messages in thread
* [PATCH v5 00/21] KVM: Extend Eager Page Splitting to the shadow MMU
@ 2022-05-13 20:27 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:27 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
This series extends KVM's Eager Page Splitting to also split huge pages
mapped by the shadow MMU, specifically **nested MMUs**.
For background on Eager Page Splitting, see:
- Proposal: https://lore.kernel.org/kvm/CALzav=dV_U4r1K9oDq4esb4mpBQDQ2ROQ5zH5wV3KpOaZrRW-A@mail.gmail.com/
- TDP MMU support: https://lore.kernel.org/kvm/20220119230739.2234394-1-dmatlack@google.com/
Splitting huge pages mapped by the shadow MMU is more complicated than
the TDP MMU, but it is also more important for performance as the shadow
MMU handles huge page write-protection faults under the write lock. See
the Performance section for more details.
The extra complexity of splitting huge pages mapped by the shadow MMU
comes from a few places:
(1) The shadow MMU has a limit on the number of shadow pages that are
allowed to be allocated. So, as a policy, Eager Page Splitting
refuses to split if there are KVM_MIN_FREE_MMU_PAGES or fewer
pages available.
(2) Huge pages may be mapped by indirect shadow pages which may have access
permission constraints from the guest (unlike the TDP MMU which is
ACC_ALL by default).
(3) Splitting a huge page may end up re-using an existing lower level
shadow page tables. This is unlike the TDP MMU which always allocates
new shadow page tables when splitting.
(4) When installing the lower level SPTEs, they must be added to the
rmap which may require allocating additional pte_list_desc structs.
In Google's internal implementation of Eager Page Splitting, we do not
handle cases (3) and (4), and intstead opts to skip splitting entirely
(case 3) or only partially splitting (case 4). This series handles the
additional cases, which requires an additional 4KiB of memory per VM to
store the extra pte_list_desc cache. However it does also avoids the need
for TLB flushes in most cases and allows KVM to split more pages mapped
by shadow paging.
The bulk of this series is just refactoring the existing MMU code in
preparation for splitting, specifically to make it possible to operate
on the MMU outside of a vCPU context.
Motivation
----------
During dirty logging, VMs using the shadow MMU suffer from:
(1) Write-protection faults on huge pages that take the MMU lock to
unmap the huge page, map a 4KiB page, and update the dirty log.
(2) Non-present faults caused by (1) that take the MMU lock to map in
the missing page.
(3) Write-protection faults on 4KiB pages that take the MMU lock to
make the page writable and update the dirty log. [Note: These faults
only take the MMU lock during shadow paging.]
The lock contention from (1), (2) and (3) can severely degrade
application performance to the point of failure. Eager page splitting
eliminates (1) by moving the splitting of huge pages off the vCPU
threads onto the thread invoking VM-ioctls to configure dirty logging,
and eliminates (2) by fully splitting each huge page into its
constituent small pages. (3) is still a concern for shadow paging
workloads (e.g. nested virtualization) but is not addressed by this
series.
Splitting in the VM-ioctl thread is useful because it can run in the
background without interrupting vCPU execution. However, it does take
the MMU lock so it may introduce some extra contention if vCPUs are
hammering the MMU lock. This is offset by the fact that eager page
splitting drops the MMU lock after splitting each SPTE if there is any
contention, and the fact that eager page splitting is reducing the MMU
lock contention from (1) and (2) above. Even workloads that only write
to 5% of their memory see massive MMU lock contention reduction during
dirty logging thanks to Eager Page Splitting (see Performance data
below).
A downside of Eager Page Splitting is that it splits all huge pages,
which may include ranges of memory that are never written to by the
guest and thus could theoretically stay huge. Workloads that write to
only a fraction of their memory may see higher TLB miss costs with Eager
Page Splitting enabled. However, that is secondary to the application
failure that otherwise may occur without Eager Page Splitting.
Further work is necessary to improve the TLB miss performance for
read-heavy workoads, such as dirty logging at 2M instead of 4K.
Performance
-----------
To measure the performance impact of Eager Page Splitting I ran
dirty_log_perf_test with support for a new flag, -n, that causes each vCPU
thread to run in L2 instead of L1. This support will be sent out in a
separate series.
To measure the imapct of customer performance, we can look at the time
it takes all vCPUs to dirty memory after dirty logging has been enabled.
Without Eager Page Splitting enabled, such dirtying must take faults to
split huge pages and bottleneck on the MMU lock.
For write-heavy workloads, there is not as much benefit since nested MMUs
still have to take the write-lock when resolving 4K write-protection
faults (case (3) in the Motivation section). But ready-heavy workloads
greatly benefit.
| Config: tdp_mmu=Y, nested, 100% writes |
| Iteration 1 dirty memory time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.367445635s | 0.359880160s |
4 | 0.503976497s | 0.418760595s |
8 | 1.328792652s | 1.442455382s |
16 | 4.609457301s | 3.649754574s |
32 | 8.751328485s | 7.659014140s |
64 | 20.438482174s | 17.890019577s |
| Config: tdp_mmu=Y, nested, 50% writes |
| Iteration 1 dirty memory time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.374082549s | 0.189881327s |
4 | 0.498175012s | 0.216221200s |
8 | 1.848155856s | 0.525316794s |
16 | 4.387725630s | 1.844867390s |
32 | 9.153260046s | 4.061645844s |
64 | 20.077600588s | 8.825413269s |
| Config: tdp_mmu=Y, nested, 5% writes |
| Iteration 1 dirty memory time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.386395635s | 0.023315599s |
4 | 0.495352933s | 0.024971794s |
8 | 1.568730321s | 0.052010563s |
16 | 4.258323166s | 0.174402708s |
32 | 9.260176347s | 0.377929203s |
64 | 19.861473882s | 0.905998574s |
Eager Page Splitting does increase the time it takes to enable dirty
logging when not using initially-all-set, since that's when KVM splits
huge pages. However, this runs in parallel with vCPU execution and drops
the MMU lock whenever there is contention.
| Config: tdp_mmu=Y, nested, 100% writes |
| Enabling dirty logging time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.001330088s | 0.018624938s |
4 | 0.002763111s | 0.037247815s |
8 | 0.005220762s | 0.074637543s |
16 | 0.010381925s | 0.149096917s |
32 | 0.022109466s | 0.307983859s |
64 | 0.085547182s | 0.854228170s |
Similarly, Eager Page Splitting increases the time it takes to clear the
dirty log for when using initially-all-set. The first time userspace
clears the dirty log, KVM will split huge pages:
| Config: tdp_mmu=Y, nested, 100% writes initially-all-set |
| Iteration 1 clear dirty log time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.001947098s | 0.019836052s |
4 | 0.003817996s | 0.039574178s |
8 | 0.007673616s | 0.079118964s |
16 | 0.015733003s | 0.158006697s |
32 | 0.031728367s | 0.330793049s |
64 | 0.108699714s | 0.891762988s |
Subsequent calls to clear the dirty log incur almost no additional cost
since KVM can very quickly determine there are no more huge pages to
split via the RMAP. This is unlike the TDP MMU which must re-traverse
the entire page table to check for huge pages.
| Config: tdp_mmu=Y, nested, 100% writes initially-all-set |
| Iteration 2 clear dirty log time |
| ------------------------------------------------------- |
vCPU Count | eager_page_split=N | eager_page_split=Y |
------------ | -------------------------- | -------------------------- |
2 | 0.009585296s | 0.009931437s |
4 | 0.019188984s | 0.019842738s |
8 | 0.038568630s | 0.039951832s |
16 | 0.077188525s | 0.079536780s |
32 | 0.156728329s | 0.163612725s |
64 | 0.418679324s | 0.337336844s |
Testing
-------
- Ran all kvm-unit-tests and KVM selftests.
- Booted a 32-bit non-PAE kernel with shadow paging to verify the
quadrant change.
- Ran dirty_log_perf_test with support for a new flag, -n, that causes
each vCPU thread to run in L2 instead of L1. This support will be
sent out in a separate series.
- Tested VM live migration with nested MMUs and huge pages. The live
migration setup consisted of an 8 vCPU 8 GiB VM running on an Intel
Cascade Lake host and backed by 1GiB HugeTLBFS memory. The VM was
running Debian 10. Inside a VM was a 6 vCPU 4Gib nested VM also
Debian 10 and backed by 2M HugeTLBFS. Inside the nested VM ran a
workload that aggressively accessed memory across 6 threads.
Tracepoints during the migration confirmes eager page splitting
occurred, both for the direct TDP MMU mappings, and the nested MMU
mappings.
Version Log
-----------
v5:
- Rebase on top of latest kvm/queue.
- Collected R-b tags from Sean and Lai.
- Add another patch to stop passing non-zero quadrant [Sean]
- Drop vcpu_or_null and __kvm_sync_page() [Sean]
- Formatting and wording changes [Sean]
- Pass role instead of sp when making huge split SPTEs [Sean]
- Fix riscv compilation error [kernel test robot]
- Document split caches protected by slots_lock [Lai]
v4:
- Limit eager page splitting to nested MMUs [Sean]
- Use memory caches for SP allocation [Sean]
- Use kvm_mmu_get_page() with NULL vCPU for EPS [Sean]
- Use u64 instead of bit field for shadow translation entry [Sean]
- Add Sean's R-b to "Use a bool" patch.
- Fix printf warning in "Cache access bits" patch.
- Fix asymmentrical pr_err_ratelimit() + WARN() [Sean]
- Drop unnecessary unsync check for huge pages [Sean]
- Eliminate use of we in comments and change logs [Sean]
- Allocate objects arrays dynamically [Ben]
v3: https://lore.kernel.org/kvm/20220401175554.1931568-1-dmatlack@google.com/
- Add R-b tags from Peter.
- Explain direct SPs in indirect MMUs in commit message [Peter]
- Change BUG_ON() to WARN_ON_ONCE() in quadrant calculation [me]
- Eliminate unnecessary gotos [Peter]
- Drop mmu_alloc_pte_list_desc() [Peter]
- Also update access cache in mmu_set_spte() if was_rmapped [Peter]
- Fix number of gfn bits in shadowed_translation cache [Peter]
- Pass sp to make_huge_page_split_spte() to derive level and exec [me]
- Eliminate flush var in kvm_rmap_zap_collapsible_sptes() [Peter]
- Drop NULL pte_list_desc cache fallback [Peter]
- Fix get_access to return sp->role.access. [me]
- Re-use split cache across calls to CLEAR_DIRTY_LOG for better perf [me]
- Top-up the split cache outside of the MMU lock when possible [me]
- Refactor prepare_to_split_huge_page() into try_split_huge_page() [me]
- Collapse PATCH 20, 23, and 24 avoid intermediate complexity [Peter]
- Update the RISC-V function stage2_ioremap() [Anup]
v2: https://lore.kernel.org/kvm/20220311002528.2230172-1-dmatlack@google.com/
- Add performance data for workloads that mix reads and writes [Peter]
- Collect R-b tags from Ben and Sean.
- Fix quadrant calculation when deriving role from parent [Sean]
- Tweak new shadow page function names [Sean]
- Move set_page_private() to allocation functions [Ben]
- Only zap collapsible SPTEs up to MAX_LEVEL-1 [Ben]
- Always top-up pte_list_desc cache to reduce complexity [Ben]
- Require mmu cache capacity field to be initialized and add WARN()
to reduce chance of programmer error [Marc]
- Fix up kvm_mmu_memory_cache struct initialization in arm64 [Marc]
v1: https://lore.kernel.org/kvm/20220203010051.2813563-1-dmatlack@google.com/
David Matlack (21):
KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs
KVM: x86/mmu: Use a bool for direct
KVM: x86/mmu: Derive shadow MMU page role from parent
KVM: x86/mmu: Always pass 0 for @quadrant when gptes are 8 bytes
KVM: x86/mmu: Decompose kvm_mmu_get_page() into separate functions
KVM: x86/mmu: Consolidate shadow page allocation and initialization
KVM: x86/mmu: Rename shadow MMU functions that deal with shadow pages
KVM: x86/mmu: Move guest PT write-protection to account_shadowed()
KVM: x86/mmu: Pass memory caches to allocate SPs separately
KVM: x86/mmu: Replace vcpu with kvm in kvm_mmu_alloc_shadow_page()
KVM: x86/mmu: Pass kvm pointer separately from vcpu to
kvm_mmu_find_shadow_page()
KVM: x86/mmu: Allow NULL @vcpu in kvm_mmu_find_shadow_page()
KVM: x86/mmu: Pass const memslot to rmap_add()
KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu
KVM: x86/mmu: Update page stats in __rmap_add()
KVM: x86/mmu: Cache the access bits of shadowed translations
KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU
KVM: x86/mmu: Zap collapsible SPTEs in shadow MMU at all possible
levels
KVM: x86/mmu: Refactor drop_large_spte()
KVM: Allow for different capacities in kvm_mmu_memory_cache structs
KVM: x86/mmu: Extend Eager Page Splitting to nested MMUs
.../admin-guide/kernel-parameters.txt | 3 +-
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/mmu.c | 5 +-
arch/mips/kvm/mips.c | 2 +
arch/riscv/kvm/mmu.c | 8 +-
arch/riscv/kvm/vcpu.c | 1 +
arch/x86/include/asm/kvm_host.h | 26 +-
arch/x86/kvm/mmu/mmu.c | 704 ++++++++++++++----
arch/x86/kvm/mmu/mmu_internal.h | 17 +-
arch/x86/kvm/mmu/paging_tmpl.h | 17 +-
arch/x86/kvm/mmu/spte.c | 16 +-
arch/x86/kvm/mmu/spte.h | 2 +-
arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
arch/x86/kvm/x86.c | 6 +
include/linux/kvm_types.h | 9 +-
virt/kvm/kvm_main.c | 20 +-
16 files changed, 671 insertions(+), 168 deletions(-)
base-commit: a3808d88461270c71d3fece5e51cc486ecdac7d0
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
* [PATCH v5 01/21] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:27 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:27 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Commit fb58a9c345f6 ("KVM: x86/mmu: Optimize MMU page cache lookup for
fully direct MMUs") skipped the unsync checks and write flood clearing
for full direct MMUs. We can extend this further to skip the checks for
all direct shadow pages. Direct shadow pages in indirect MMUs (i.e.
shadow paging) are used when shadowing a guest huge page with smaller
pages. Such direct shadow pages, like their counterparts in fully direct
MMUs, are never marked unsynced or have a non-zero write-flooding count.
Checking sp->role.direct also generates better code than checking
direct_map because, due to register pressure, direct_map has to get
shoved onto the stack and then pulled back off.
No functional change intended.
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index efe5a3dca1e0..774810d8a2ed 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2026,7 +2026,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
int direct,
unsigned int access)
{
- bool direct_mmu = vcpu->arch.mmu->root_role.direct;
union kvm_mmu_page_role role;
struct hlist_head *sp_list;
unsigned quadrant;
@@ -2070,7 +2069,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
continue;
}
- if (direct_mmu)
+ /* unsync and write-flooding only apply to indirect SPs. */
+ if (sp->role.direct)
goto trace_get_page;
if (sp->unsync) {
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 01/21] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs
@ 2022-05-13 20:27 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:27 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Commit fb58a9c345f6 ("KVM: x86/mmu: Optimize MMU page cache lookup for
fully direct MMUs") skipped the unsync checks and write flood clearing
for full direct MMUs. We can extend this further to skip the checks for
all direct shadow pages. Direct shadow pages in indirect MMUs (i.e.
shadow paging) are used when shadowing a guest huge page with smaller
pages. Such direct shadow pages, like their counterparts in fully direct
MMUs, are never marked unsynced or have a non-zero write-flooding count.
Checking sp->role.direct also generates better code than checking
direct_map because, due to register pressure, direct_map has to get
shoved onto the stack and then pulled back off.
No functional change intended.
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index efe5a3dca1e0..774810d8a2ed 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2026,7 +2026,6 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
int direct,
unsigned int access)
{
- bool direct_mmu = vcpu->arch.mmu->root_role.direct;
union kvm_mmu_page_role role;
struct hlist_head *sp_list;
unsigned quadrant;
@@ -2070,7 +2069,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
continue;
}
- if (direct_mmu)
+ /* unsync and write-flooding only apply to indirect SPs. */
+ if (sp->role.direct)
goto trace_get_page;
if (sp->unsync) {
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 02/21] KVM: x86/mmu: Use a bool for direct
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
The parameter "direct" can either be true or false, and all of the
callers pass in a bool variable or true/false literal, so just use the
type bool.
No functional change intended.
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 774810d8a2ed..34fb0cddff2b 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1690,7 +1690,7 @@ static void drop_parent_pte(struct kvm_mmu_page *sp,
mmu_spte_clear_no_track(parent_pte);
}
-static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct)
+static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, bool direct)
{
struct kvm_mmu_page *sp;
@@ -2023,7 +2023,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
gfn_t gfn,
gva_t gaddr,
unsigned level,
- int direct,
+ bool direct,
unsigned int access)
{
union kvm_mmu_page_role role;
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 02/21] KVM: x86/mmu: Use a bool for direct
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
The parameter "direct" can either be true or false, and all of the
callers pass in a bool variable or true/false literal, so just use the
type bool.
No functional change intended.
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 774810d8a2ed..34fb0cddff2b 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1690,7 +1690,7 @@ static void drop_parent_pte(struct kvm_mmu_page *sp,
mmu_spte_clear_no_track(parent_pte);
}
-static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct)
+static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, bool direct)
{
struct kvm_mmu_page *sp;
@@ -2023,7 +2023,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
gfn_t gfn,
gva_t gaddr,
unsigned level,
- int direct,
+ bool direct,
unsigned int access)
{
union kvm_mmu_page_role role;
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 03/21] KVM: x86/mmu: Derive shadow MMU page role from parent
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Instead of computing the shadow page role from scratch for every new
page, derive most of the information from the parent shadow page. This
eliminates the dependency on the vCPU root role to allocate shadow page
tables, and reduces the number of parameters to kvm_mmu_get_page().
Preemptively split out the role calculation to a separate function for
use in a following commit.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 103 +++++++++++++++++++++++----------
arch/x86/kvm/mmu/paging_tmpl.h | 9 +--
2 files changed, 77 insertions(+), 35 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 34fb0cddff2b..a927a062a598 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2019,33 +2019,15 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sptep_to_sp(spte));
}
-static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
- gfn_t gfn,
- gva_t gaddr,
- unsigned level,
- bool direct,
- unsigned int access)
+static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
+ union kvm_mmu_page_role role)
{
- union kvm_mmu_page_role role;
struct hlist_head *sp_list;
- unsigned quadrant;
struct kvm_mmu_page *sp;
int ret;
int collisions = 0;
LIST_HEAD(invalid_list);
- role = vcpu->arch.mmu->root_role;
- role.level = level;
- role.direct = direct;
- role.access = access;
- if (role.has_4_byte_gpte) {
- quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
- quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
- role.quadrant = quadrant;
- }
- if (level <= vcpu->arch.mmu->cpu_role.base.level)
- role.passthrough = 0;
-
sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
for_each_valid_sp(vcpu->kvm, sp, sp_list) {
if (sp->gfn != gfn) {
@@ -2063,7 +2045,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
* Unsync pages must not be left as is, because the new
* upper-level page will be write-protected.
*/
- if (level > PG_LEVEL_4K && sp->unsync)
+ if (role.level > PG_LEVEL_4K && sp->unsync)
kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
&invalid_list);
continue;
@@ -2104,14 +2086,14 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
++vcpu->kvm->stat.mmu_cache_miss;
- sp = kvm_mmu_alloc_page(vcpu, direct);
+ sp = kvm_mmu_alloc_page(vcpu, role.direct);
sp->gfn = gfn;
sp->role = role;
hlist_add_head(&sp->hash_link, sp_list);
if (sp_has_gptes(sp)) {
account_shadowed(vcpu->kvm, sp);
- if (level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
+ if (role.level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
}
trace_kvm_mmu_get_page(sp, true);
@@ -2123,6 +2105,55 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
return sp;
}
+static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, u32 access)
+{
+ struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep);
+ union kvm_mmu_page_role role;
+
+ role = parent_sp->role;
+ role.level--;
+ role.access = access;
+ role.direct = direct;
+ role.passthrough = 0;
+
+ /*
+ * If the guest has 4-byte PTEs then that means it's using 32-bit,
+ * 2-level, non-PAE paging. KVM shadows such guests with PAE paging
+ * (i.e. 8-byte PTEs). The difference in PTE size means that KVM must
+ * shadow each guest page table with multiple shadow page tables, which
+ * requires extra bookkeeping in the role.
+ *
+ * Specifically, to shadow the guest's page directory (which covers a
+ * 4GiB address space), KVM uses 4 PAE page directories, each mapping
+ * 1GiB of the address space. @role.quadrant encodes which quarter of
+ * the address space each maps.
+ *
+ * To shadow the guest's page tables (which each map a 4MiB region), KVM
+ * uses 2 PAE page tables, each mapping a 2MiB region. For these,
+ * @role.quadrant encodes which half of the region they map.
+ *
+ * Note, the 4 PAE page directories are pre-allocated and the quadrant
+ * assigned in mmu_alloc_root(). So only page tables need to be handled
+ * here.
+ */
+ if (role.has_4_byte_gpte) {
+ WARN_ON_ONCE(role.level != PG_LEVEL_4K);
+ role.quadrant = (sptep - parent_sp->spt) % 2;
+ }
+
+ return role;
+}
+
+static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu,
+ u64 *sptep, gfn_t gfn,
+ bool direct, u32 access)
+{
+ union kvm_mmu_page_role role;
+
+ role = kvm_mmu_child_role(sptep, direct, access);
+ return kvm_mmu_get_page(vcpu, gfn, role);
+}
+
static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator,
struct kvm_vcpu *vcpu, hpa_t root,
u64 addr)
@@ -2965,8 +2996,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
if (is_shadow_present_pte(*it.sptep))
continue;
- sp = kvm_mmu_get_page(vcpu, base_gfn, it.addr,
- it.level - 1, true, ACC_ALL);
+ sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL);
link_shadow_page(vcpu, it.sptep, sp);
if (fault->is_tdp && fault->huge_page_disallowed &&
@@ -3369,12 +3399,24 @@ static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn)
return ret;
}
-static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva,
+static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
u8 level, bool direct)
{
+ union kvm_mmu_page_role role;
struct kvm_mmu_page *sp;
- sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL);
+ role = vcpu->arch.mmu->root_role;
+ role.level = level;
+ role.direct = direct;
+ role.access = ACC_ALL;
+
+ if (role.has_4_byte_gpte)
+ role.quadrant = quadrant;
+
+ if (level <= vcpu->arch.mmu->cpu_role.base.level)
+ role.passthrough = 0;
+
+ sp = kvm_mmu_get_page(vcpu, gfn, role);
++sp->root_count;
return __pa(sp->spt);
@@ -3408,8 +3450,8 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
for (i = 0; i < 4; ++i) {
WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i]));
- root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT),
- i << 30, PT32_ROOT_LEVEL, true);
+ root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), i,
+ PT32_ROOT_LEVEL, true);
mmu->pae_root[i] = root | PT_PRESENT_MASK |
shadow_me_mask;
}
@@ -3578,8 +3620,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
root_gfn = pdptrs[i] >> PAGE_SHIFT;
}
- root = mmu_alloc_root(vcpu, root_gfn, i << 30,
- PT32_ROOT_LEVEL, false);
+ root = mmu_alloc_root(vcpu, root_gfn, i, PT32_ROOT_LEVEL, false);
mmu->pae_root[i] = root | pm_mask;
}
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index db80f7ccaa4e..fd73c857af90 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -648,8 +648,9 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
if (!is_shadow_present_pte(*it.sptep)) {
table_gfn = gw->table_gfn[it.level - 2];
access = gw->pt_access[it.level - 2];
- sp = kvm_mmu_get_page(vcpu, table_gfn, fault->addr,
- it.level-1, false, access);
+ sp = kvm_mmu_get_child_sp(vcpu, it.sptep, table_gfn,
+ false, access);
+
/*
* We must synchronize the pagetable before linking it
* because the guest doesn't need to flush tlb when
@@ -705,8 +706,8 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
drop_large_spte(vcpu, it.sptep);
if (!is_shadow_present_pte(*it.sptep)) {
- sp = kvm_mmu_get_page(vcpu, base_gfn, fault->addr,
- it.level - 1, true, direct_access);
+ sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn,
+ true, direct_access);
link_shadow_page(vcpu, it.sptep, sp);
if (fault->huge_page_disallowed &&
fault->req_level >= it.level)
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 03/21] KVM: x86/mmu: Derive shadow MMU page role from parent
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Instead of computing the shadow page role from scratch for every new
page, derive most of the information from the parent shadow page. This
eliminates the dependency on the vCPU root role to allocate shadow page
tables, and reduces the number of parameters to kvm_mmu_get_page().
Preemptively split out the role calculation to a separate function for
use in a following commit.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 103 +++++++++++++++++++++++----------
arch/x86/kvm/mmu/paging_tmpl.h | 9 +--
2 files changed, 77 insertions(+), 35 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 34fb0cddff2b..a927a062a598 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2019,33 +2019,15 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sptep_to_sp(spte));
}
-static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
- gfn_t gfn,
- gva_t gaddr,
- unsigned level,
- bool direct,
- unsigned int access)
+static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
+ union kvm_mmu_page_role role)
{
- union kvm_mmu_page_role role;
struct hlist_head *sp_list;
- unsigned quadrant;
struct kvm_mmu_page *sp;
int ret;
int collisions = 0;
LIST_HEAD(invalid_list);
- role = vcpu->arch.mmu->root_role;
- role.level = level;
- role.direct = direct;
- role.access = access;
- if (role.has_4_byte_gpte) {
- quadrant = gaddr >> (PAGE_SHIFT + (PT64_PT_BITS * level));
- quadrant &= (1 << ((PT32_PT_BITS - PT64_PT_BITS) * level)) - 1;
- role.quadrant = quadrant;
- }
- if (level <= vcpu->arch.mmu->cpu_role.base.level)
- role.passthrough = 0;
-
sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
for_each_valid_sp(vcpu->kvm, sp, sp_list) {
if (sp->gfn != gfn) {
@@ -2063,7 +2045,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
* Unsync pages must not be left as is, because the new
* upper-level page will be write-protected.
*/
- if (level > PG_LEVEL_4K && sp->unsync)
+ if (role.level > PG_LEVEL_4K && sp->unsync)
kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
&invalid_list);
continue;
@@ -2104,14 +2086,14 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
++vcpu->kvm->stat.mmu_cache_miss;
- sp = kvm_mmu_alloc_page(vcpu, direct);
+ sp = kvm_mmu_alloc_page(vcpu, role.direct);
sp->gfn = gfn;
sp->role = role;
hlist_add_head(&sp->hash_link, sp_list);
if (sp_has_gptes(sp)) {
account_shadowed(vcpu->kvm, sp);
- if (level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
+ if (role.level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
}
trace_kvm_mmu_get_page(sp, true);
@@ -2123,6 +2105,55 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
return sp;
}
+static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, u32 access)
+{
+ struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep);
+ union kvm_mmu_page_role role;
+
+ role = parent_sp->role;
+ role.level--;
+ role.access = access;
+ role.direct = direct;
+ role.passthrough = 0;
+
+ /*
+ * If the guest has 4-byte PTEs then that means it's using 32-bit,
+ * 2-level, non-PAE paging. KVM shadows such guests with PAE paging
+ * (i.e. 8-byte PTEs). The difference in PTE size means that KVM must
+ * shadow each guest page table with multiple shadow page tables, which
+ * requires extra bookkeeping in the role.
+ *
+ * Specifically, to shadow the guest's page directory (which covers a
+ * 4GiB address space), KVM uses 4 PAE page directories, each mapping
+ * 1GiB of the address space. @role.quadrant encodes which quarter of
+ * the address space each maps.
+ *
+ * To shadow the guest's page tables (which each map a 4MiB region), KVM
+ * uses 2 PAE page tables, each mapping a 2MiB region. For these,
+ * @role.quadrant encodes which half of the region they map.
+ *
+ * Note, the 4 PAE page directories are pre-allocated and the quadrant
+ * assigned in mmu_alloc_root(). So only page tables need to be handled
+ * here.
+ */
+ if (role.has_4_byte_gpte) {
+ WARN_ON_ONCE(role.level != PG_LEVEL_4K);
+ role.quadrant = (sptep - parent_sp->spt) % 2;
+ }
+
+ return role;
+}
+
+static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu,
+ u64 *sptep, gfn_t gfn,
+ bool direct, u32 access)
+{
+ union kvm_mmu_page_role role;
+
+ role = kvm_mmu_child_role(sptep, direct, access);
+ return kvm_mmu_get_page(vcpu, gfn, role);
+}
+
static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator,
struct kvm_vcpu *vcpu, hpa_t root,
u64 addr)
@@ -2965,8 +2996,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
if (is_shadow_present_pte(*it.sptep))
continue;
- sp = kvm_mmu_get_page(vcpu, base_gfn, it.addr,
- it.level - 1, true, ACC_ALL);
+ sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn, true, ACC_ALL);
link_shadow_page(vcpu, it.sptep, sp);
if (fault->is_tdp && fault->huge_page_disallowed &&
@@ -3369,12 +3399,24 @@ static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn)
return ret;
}
-static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva,
+static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
u8 level, bool direct)
{
+ union kvm_mmu_page_role role;
struct kvm_mmu_page *sp;
- sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL);
+ role = vcpu->arch.mmu->root_role;
+ role.level = level;
+ role.direct = direct;
+ role.access = ACC_ALL;
+
+ if (role.has_4_byte_gpte)
+ role.quadrant = quadrant;
+
+ if (level <= vcpu->arch.mmu->cpu_role.base.level)
+ role.passthrough = 0;
+
+ sp = kvm_mmu_get_page(vcpu, gfn, role);
++sp->root_count;
return __pa(sp->spt);
@@ -3408,8 +3450,8 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
for (i = 0; i < 4; ++i) {
WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i]));
- root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT),
- i << 30, PT32_ROOT_LEVEL, true);
+ root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), i,
+ PT32_ROOT_LEVEL, true);
mmu->pae_root[i] = root | PT_PRESENT_MASK |
shadow_me_mask;
}
@@ -3578,8 +3620,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
root_gfn = pdptrs[i] >> PAGE_SHIFT;
}
- root = mmu_alloc_root(vcpu, root_gfn, i << 30,
- PT32_ROOT_LEVEL, false);
+ root = mmu_alloc_root(vcpu, root_gfn, i, PT32_ROOT_LEVEL, false);
mmu->pae_root[i] = root | pm_mask;
}
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index db80f7ccaa4e..fd73c857af90 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -648,8 +648,9 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
if (!is_shadow_present_pte(*it.sptep)) {
table_gfn = gw->table_gfn[it.level - 2];
access = gw->pt_access[it.level - 2];
- sp = kvm_mmu_get_page(vcpu, table_gfn, fault->addr,
- it.level-1, false, access);
+ sp = kvm_mmu_get_child_sp(vcpu, it.sptep, table_gfn,
+ false, access);
+
/*
* We must synchronize the pagetable before linking it
* because the guest doesn't need to flush tlb when
@@ -705,8 +706,8 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault,
drop_large_spte(vcpu, it.sptep);
if (!is_shadow_present_pte(*it.sptep)) {
- sp = kvm_mmu_get_page(vcpu, base_gfn, fault->addr,
- it.level - 1, true, direct_access);
+ sp = kvm_mmu_get_child_sp(vcpu, it.sptep, base_gfn,
+ true, direct_access);
link_shadow_page(vcpu, it.sptep, sp);
if (fault->huge_page_disallowed &&
fault->req_level >= it.level)
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 04/21] KVM: x86/mmu: Always pass 0 for @quadrant when gptes are 8 bytes
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
The quadrant is only used when gptes are 4 bytes, but
mmu_alloc_{direct,shadow}_roots() pass in a non-zero quadrant for PAE
page directories regardless. Make this less confusing by only passing in
a non-zero quadrant when it is actually necessary.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a927a062a598..34786244ebad 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3409,9 +3409,10 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
role.level = level;
role.direct = direct;
role.access = ACC_ALL;
+ role.quadrant = quadrant;
- if (role.has_4_byte_gpte)
- role.quadrant = quadrant;
+ WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte);
+ WARN_ON_ONCE(direct && role.has_4_byte_gpte);
if (level <= vcpu->arch.mmu->cpu_role.base.level)
role.passthrough = 0;
@@ -3450,7 +3451,7 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
for (i = 0; i < 4; ++i) {
WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i]));
- root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), i,
+ root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), 0,
PT32_ROOT_LEVEL, true);
mmu->pae_root[i] = root | PT_PRESENT_MASK |
shadow_me_mask;
@@ -3535,6 +3536,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
struct kvm_mmu *mmu = vcpu->arch.mmu;
u64 pdptrs[4], pm_mask;
gfn_t root_gfn, root_pgd;
+ unsigned int quadrant;
hpa_t root;
unsigned i;
int r;
@@ -3620,7 +3622,15 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
root_gfn = pdptrs[i] >> PAGE_SHIFT;
}
- root = mmu_alloc_root(vcpu, root_gfn, i, PT32_ROOT_LEVEL, false);
+ /*
+ * If shadowing 32-bit non-PAE page tables, each PAE page
+ * directory maps one quarter of the guest's non-PAE page
+ * directory. Othwerise each PAE page direct shadows one guest
+ * PAE page directory so that quadrant should be 0.
+ */
+ quadrant = (mmu->cpu_role.base.level == PT32_ROOT_LEVEL) ? i : 0;
+
+ root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL, false);
mmu->pae_root[i] = root | pm_mask;
}
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 04/21] KVM: x86/mmu: Always pass 0 for @quadrant when gptes are 8 bytes
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
The quadrant is only used when gptes are 4 bytes, but
mmu_alloc_{direct,shadow}_roots() pass in a non-zero quadrant for PAE
page directories regardless. Make this less confusing by only passing in
a non-zero quadrant when it is actually necessary.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index a927a062a598..34786244ebad 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3409,9 +3409,10 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
role.level = level;
role.direct = direct;
role.access = ACC_ALL;
+ role.quadrant = quadrant;
- if (role.has_4_byte_gpte)
- role.quadrant = quadrant;
+ WARN_ON_ONCE(quadrant && !role.has_4_byte_gpte);
+ WARN_ON_ONCE(direct && role.has_4_byte_gpte);
if (level <= vcpu->arch.mmu->cpu_role.base.level)
role.passthrough = 0;
@@ -3450,7 +3451,7 @@ static int mmu_alloc_direct_roots(struct kvm_vcpu *vcpu)
for (i = 0; i < 4; ++i) {
WARN_ON_ONCE(IS_VALID_PAE_ROOT(mmu->pae_root[i]));
- root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), i,
+ root = mmu_alloc_root(vcpu, i << (30 - PAGE_SHIFT), 0,
PT32_ROOT_LEVEL, true);
mmu->pae_root[i] = root | PT_PRESENT_MASK |
shadow_me_mask;
@@ -3535,6 +3536,7 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
struct kvm_mmu *mmu = vcpu->arch.mmu;
u64 pdptrs[4], pm_mask;
gfn_t root_gfn, root_pgd;
+ unsigned int quadrant;
hpa_t root;
unsigned i;
int r;
@@ -3620,7 +3622,15 @@ static int mmu_alloc_shadow_roots(struct kvm_vcpu *vcpu)
root_gfn = pdptrs[i] >> PAGE_SHIFT;
}
- root = mmu_alloc_root(vcpu, root_gfn, i, PT32_ROOT_LEVEL, false);
+ /*
+ * If shadowing 32-bit non-PAE page tables, each PAE page
+ * directory maps one quarter of the guest's non-PAE page
+ * directory. Othwerise each PAE page direct shadows one guest
+ * PAE page directory so that quadrant should be 0.
+ */
+ quadrant = (mmu->cpu_role.base.level == PT32_ROOT_LEVEL) ? i : 0;
+
+ root = mmu_alloc_root(vcpu, root_gfn, quadrant, PT32_ROOT_LEVEL, false);
mmu->pae_root[i] = root | pm_mask;
}
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 05/21] KVM: x86/mmu: Decompose kvm_mmu_get_page() into separate functions
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Decompose kvm_mmu_get_page() into separate helper functions to increase
readability and prepare for allocating shadow pages without a vcpu
pointer.
Specifically, pull the guts of kvm_mmu_get_page() into 2 helper
functions:
kvm_mmu_find_shadow_page() -
Walks the page hash checking for any existing mmu pages that match the
given gfn and role.
kvm_mmu_alloc_shadow_page()
Allocates and initializes an entirely new kvm_mmu_page. This currently
requries a vcpu pointer for allocation and looking up the memslot but
that will be removed in a future commit.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 52 +++++++++++++++++++++++++++++++-----------
1 file changed, 39 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 34786244ebad..ce334eaeef22 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2019,16 +2019,16 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sptep_to_sp(spte));
}
-static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
- union kvm_mmu_page_role role)
+static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
+ gfn_t gfn,
+ struct hlist_head *sp_list,
+ union kvm_mmu_page_role role)
{
- struct hlist_head *sp_list;
struct kvm_mmu_page *sp;
int ret;
int collisions = 0;
LIST_HEAD(invalid_list);
- sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
for_each_valid_sp(vcpu->kvm, sp, sp_list) {
if (sp->gfn != gfn) {
collisions++;
@@ -2053,7 +2053,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
/* unsync and write-flooding only apply to indirect SPs. */
if (sp->role.direct)
- goto trace_get_page;
+ goto out;
if (sp->unsync) {
/*
@@ -2079,14 +2079,26 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
__clear_sp_write_flooding_count(sp);
-trace_get_page:
- trace_kvm_mmu_get_page(sp, false);
goto out;
}
+ sp = NULL;
++vcpu->kvm->stat.mmu_cache_miss;
- sp = kvm_mmu_alloc_page(vcpu, role.direct);
+out:
+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
+
+ if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
+ vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
+ return sp;
+}
+
+static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
+ gfn_t gfn,
+ struct hlist_head *sp_list,
+ union kvm_mmu_page_role role)
+{
+ struct kvm_mmu_page *sp = kvm_mmu_alloc_page(vcpu, role.direct);
sp->gfn = gfn;
sp->role = role;
@@ -2096,12 +2108,26 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
if (role.level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
}
- trace_kvm_mmu_get_page(sp, true);
-out:
- kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
- if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
- vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
+ return sp;
+}
+
+static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
+ union kvm_mmu_page_role role)
+{
+ struct hlist_head *sp_list;
+ struct kvm_mmu_page *sp;
+ bool created = false;
+
+ sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
+
+ sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
+ if (!sp) {
+ created = true;
+ sp = kvm_mmu_alloc_shadow_page(vcpu, gfn, sp_list, role);
+ }
+
+ trace_kvm_mmu_get_page(sp, created);
return sp;
}
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 05/21] KVM: x86/mmu: Decompose kvm_mmu_get_page() into separate functions
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Decompose kvm_mmu_get_page() into separate helper functions to increase
readability and prepare for allocating shadow pages without a vcpu
pointer.
Specifically, pull the guts of kvm_mmu_get_page() into 2 helper
functions:
kvm_mmu_find_shadow_page() -
Walks the page hash checking for any existing mmu pages that match the
given gfn and role.
kvm_mmu_alloc_shadow_page()
Allocates and initializes an entirely new kvm_mmu_page. This currently
requries a vcpu pointer for allocation and looking up the memslot but
that will be removed in a future commit.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 52 +++++++++++++++++++++++++++++++-----------
1 file changed, 39 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 34786244ebad..ce334eaeef22 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2019,16 +2019,16 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sptep_to_sp(spte));
}
-static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
- union kvm_mmu_page_role role)
+static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
+ gfn_t gfn,
+ struct hlist_head *sp_list,
+ union kvm_mmu_page_role role)
{
- struct hlist_head *sp_list;
struct kvm_mmu_page *sp;
int ret;
int collisions = 0;
LIST_HEAD(invalid_list);
- sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
for_each_valid_sp(vcpu->kvm, sp, sp_list) {
if (sp->gfn != gfn) {
collisions++;
@@ -2053,7 +2053,7 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
/* unsync and write-flooding only apply to indirect SPs. */
if (sp->role.direct)
- goto trace_get_page;
+ goto out;
if (sp->unsync) {
/*
@@ -2079,14 +2079,26 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
__clear_sp_write_flooding_count(sp);
-trace_get_page:
- trace_kvm_mmu_get_page(sp, false);
goto out;
}
+ sp = NULL;
++vcpu->kvm->stat.mmu_cache_miss;
- sp = kvm_mmu_alloc_page(vcpu, role.direct);
+out:
+ kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
+
+ if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
+ vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
+ return sp;
+}
+
+static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
+ gfn_t gfn,
+ struct hlist_head *sp_list,
+ union kvm_mmu_page_role role)
+{
+ struct kvm_mmu_page *sp = kvm_mmu_alloc_page(vcpu, role.direct);
sp->gfn = gfn;
sp->role = role;
@@ -2096,12 +2108,26 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
if (role.level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
}
- trace_kvm_mmu_get_page(sp, true);
-out:
- kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
- if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
- vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
+ return sp;
+}
+
+static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
+ union kvm_mmu_page_role role)
+{
+ struct hlist_head *sp_list;
+ struct kvm_mmu_page *sp;
+ bool created = false;
+
+ sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
+
+ sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
+ if (!sp) {
+ created = true;
+ sp = kvm_mmu_alloc_shadow_page(vcpu, gfn, sp_list, role);
+ }
+
+ trace_kvm_mmu_get_page(sp, created);
return sp;
}
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 06/21] KVM: x86/mmu: Consolidate shadow page allocation and initialization
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Consolidate kvm_mmu_alloc_page() and kvm_mmu_alloc_shadow_page() under
the latter so that all shadow page allocation and initialization happens
in one place.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 39 +++++++++++++++++----------------------
1 file changed, 17 insertions(+), 22 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ce334eaeef22..fd749748b280 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1690,27 +1690,6 @@ static void drop_parent_pte(struct kvm_mmu_page *sp,
mmu_spte_clear_no_track(parent_pte);
}
-static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, bool direct)
-{
- struct kvm_mmu_page *sp;
-
- sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
- sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
- if (!direct)
- sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
- set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
-
- /*
- * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages()
- * depends on valid pages being added to the head of the list. See
- * comments in kvm_zap_obsolete_pages().
- */
- sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
- list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
- kvm_mod_used_mmu_pages(vcpu->kvm, +1);
- return sp;
-}
-
static void mark_unsync(u64 *spte);
static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)
{
@@ -2098,7 +2077,23 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
struct hlist_head *sp_list,
union kvm_mmu_page_role role)
{
- struct kvm_mmu_page *sp = kvm_mmu_alloc_page(vcpu, role.direct);
+ struct kvm_mmu_page *sp;
+
+ sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
+ sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
+ if (!role.direct)
+ sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
+
+ set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
+
+ /*
+ * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages()
+ * depends on valid pages being added to the head of the list. See
+ * comments in kvm_zap_obsolete_pages().
+ */
+ sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
+ list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
+ kvm_mod_used_mmu_pages(vcpu->kvm, +1);
sp->gfn = gfn;
sp->role = role;
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 06/21] KVM: x86/mmu: Consolidate shadow page allocation and initialization
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Consolidate kvm_mmu_alloc_page() and kvm_mmu_alloc_shadow_page() under
the latter so that all shadow page allocation and initialization happens
in one place.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 39 +++++++++++++++++----------------------
1 file changed, 17 insertions(+), 22 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ce334eaeef22..fd749748b280 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1690,27 +1690,6 @@ static void drop_parent_pte(struct kvm_mmu_page *sp,
mmu_spte_clear_no_track(parent_pte);
}
-static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, bool direct)
-{
- struct kvm_mmu_page *sp;
-
- sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
- sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
- if (!direct)
- sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
- set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
-
- /*
- * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages()
- * depends on valid pages being added to the head of the list. See
- * comments in kvm_zap_obsolete_pages().
- */
- sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
- list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
- kvm_mod_used_mmu_pages(vcpu->kvm, +1);
- return sp;
-}
-
static void mark_unsync(u64 *spte);
static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)
{
@@ -2098,7 +2077,23 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
struct hlist_head *sp_list,
union kvm_mmu_page_role role)
{
- struct kvm_mmu_page *sp = kvm_mmu_alloc_page(vcpu, role.direct);
+ struct kvm_mmu_page *sp;
+
+ sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
+ sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
+ if (!role.direct)
+ sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
+
+ set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
+
+ /*
+ * active_mmu_pages must be a FIFO list, as kvm_zap_obsolete_pages()
+ * depends on valid pages being added to the head of the list. See
+ * comments in kvm_zap_obsolete_pages().
+ */
+ sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
+ list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
+ kvm_mod_used_mmu_pages(vcpu->kvm, +1);
sp->gfn = gfn;
sp->role = role;
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 07/21] KVM: x86/mmu: Rename shadow MMU functions that deal with shadow pages
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Rename 2 functions:
kvm_mmu_get_page() -> kvm_mmu_get_shadow_page()
kvm_mmu_free_page() -> kvm_mmu_free_shadow_page()
This change makes it clear that these functions deal with shadow pages
rather than struct pages. It also aligns these functions with the naming
scheme for kvm_mmu_find_shadow_page() and kvm_mmu_alloc_shadow_page().
Prefer "shadow_page" over the shorter "sp" since these are core
functions and the line lengths aren't terrible.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index fd749748b280..4bbb6821f861 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1652,7 +1652,7 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr)
percpu_counter_add(&kvm_total_used_mmu_pages, nr);
}
-static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
+static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp)
{
MMU_WARN_ON(!is_empty_shadow_page(sp->spt));
hlist_del(&sp->hash_link);
@@ -2107,8 +2107,9 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
return sp;
}
-static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
- union kvm_mmu_page_role role)
+static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+ gfn_t gfn,
+ union kvm_mmu_page_role role)
{
struct hlist_head *sp_list;
struct kvm_mmu_page *sp;
@@ -2172,7 +2173,7 @@ static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu,
union kvm_mmu_page_role role;
role = kvm_mmu_child_role(sptep, direct, access);
- return kvm_mmu_get_page(vcpu, gfn, role);
+ return kvm_mmu_get_shadow_page(vcpu, gfn, role);
}
static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator,
@@ -2448,7 +2449,7 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
list_for_each_entry_safe(sp, nsp, invalid_list, link) {
WARN_ON(!sp->role.invalid || sp->root_count);
- kvm_mmu_free_page(sp);
+ kvm_mmu_free_shadow_page(sp);
}
}
@@ -3438,7 +3439,7 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
if (level <= vcpu->arch.mmu->cpu_role.base.level)
role.passthrough = 0;
- sp = kvm_mmu_get_page(vcpu, gfn, role);
+ sp = kvm_mmu_get_shadow_page(vcpu, gfn, role);
++sp->root_count;
return __pa(sp->spt);
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 07/21] KVM: x86/mmu: Rename shadow MMU functions that deal with shadow pages
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Rename 2 functions:
kvm_mmu_get_page() -> kvm_mmu_get_shadow_page()
kvm_mmu_free_page() -> kvm_mmu_free_shadow_page()
This change makes it clear that these functions deal with shadow pages
rather than struct pages. It also aligns these functions with the naming
scheme for kvm_mmu_find_shadow_page() and kvm_mmu_alloc_shadow_page().
Prefer "shadow_page" over the shorter "sp" since these are core
functions and the line lengths aren't terrible.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index fd749748b280..4bbb6821f861 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1652,7 +1652,7 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr)
percpu_counter_add(&kvm_total_used_mmu_pages, nr);
}
-static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
+static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp)
{
MMU_WARN_ON(!is_empty_shadow_page(sp->spt));
hlist_del(&sp->hash_link);
@@ -2107,8 +2107,9 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
return sp;
}
-static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, gfn_t gfn,
- union kvm_mmu_page_role role)
+static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+ gfn_t gfn,
+ union kvm_mmu_page_role role)
{
struct hlist_head *sp_list;
struct kvm_mmu_page *sp;
@@ -2172,7 +2173,7 @@ static struct kvm_mmu_page *kvm_mmu_get_child_sp(struct kvm_vcpu *vcpu,
union kvm_mmu_page_role role;
role = kvm_mmu_child_role(sptep, direct, access);
- return kvm_mmu_get_page(vcpu, gfn, role);
+ return kvm_mmu_get_shadow_page(vcpu, gfn, role);
}
static void shadow_walk_init_using_root(struct kvm_shadow_walk_iterator *iterator,
@@ -2448,7 +2449,7 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
list_for_each_entry_safe(sp, nsp, invalid_list, link) {
WARN_ON(!sp->role.invalid || sp->root_count);
- kvm_mmu_free_page(sp);
+ kvm_mmu_free_shadow_page(sp);
}
}
@@ -3438,7 +3439,7 @@ static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
if (level <= vcpu->arch.mmu->cpu_role.base.level)
role.passthrough = 0;
- sp = kvm_mmu_get_page(vcpu, gfn, role);
+ sp = kvm_mmu_get_shadow_page(vcpu, gfn, role);
++sp->root_count;
return __pa(sp->spt);
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 08/21] KVM: x86/mmu: Move guest PT write-protection to account_shadowed()
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Move the code that write-protects newly-shadowed guest page tables into
account_shadowed(). This avoids a extra gfn-to-memslot lookup and is a
more logical place for this code to live. But most importantly, this
reduces kvm_mmu_alloc_shadow_page()'s reliance on having a struct
kvm_vcpu pointer, which will be necessary when creating new shadow pages
during VM ioctls for eager page splitting.
Note, it is safe to drop the role.level == PG_LEVEL_4K check since
account_shadowed() returns early if role.level > PG_LEVEL_4K.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4bbb6821f861..16001b019e1a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -792,6 +792,9 @@ static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
KVM_PAGE_TRACK_WRITE);
kvm_mmu_gfn_disallow_lpage(slot, gfn);
+
+ if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, PG_LEVEL_4K))
+ kvm_flush_remote_tlbs_with_address(kvm, gfn, 1);
}
void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp)
@@ -2098,11 +2101,8 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
sp->gfn = gfn;
sp->role = role;
hlist_add_head(&sp->hash_link, sp_list);
- if (sp_has_gptes(sp)) {
+ if (sp_has_gptes(sp))
account_shadowed(vcpu->kvm, sp);
- if (role.level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
- kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
- }
return sp;
}
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 08/21] KVM: x86/mmu: Move guest PT write-protection to account_shadowed()
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Move the code that write-protects newly-shadowed guest page tables into
account_shadowed(). This avoids a extra gfn-to-memslot lookup and is a
more logical place for this code to live. But most importantly, this
reduces kvm_mmu_alloc_shadow_page()'s reliance on having a struct
kvm_vcpu pointer, which will be necessary when creating new shadow pages
during VM ioctls for eager page splitting.
Note, it is safe to drop the role.level == PG_LEVEL_4K check since
account_shadowed() returns early if role.level > PG_LEVEL_4K.
No functional change intended.
Reviewed-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4bbb6821f861..16001b019e1a 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -792,6 +792,9 @@ static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp)
KVM_PAGE_TRACK_WRITE);
kvm_mmu_gfn_disallow_lpage(slot, gfn);
+
+ if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn, PG_LEVEL_4K))
+ kvm_flush_remote_tlbs_with_address(kvm, gfn, 1);
}
void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp)
@@ -2098,11 +2101,8 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
sp->gfn = gfn;
sp->role = role;
hlist_add_head(&sp->hash_link, sp_list);
- if (sp_has_gptes(sp)) {
+ if (sp_has_gptes(sp))
account_shadowed(vcpu->kvm, sp);
- if (role.level == PG_LEVEL_4K && kvm_vcpu_write_protect_gfn(vcpu, gfn))
- kvm_flush_remote_tlbs_with_address(vcpu->kvm, gfn, 1);
- }
return sp;
}
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 09/21] KVM: x86/mmu: Pass memory caches to allocate SPs separately
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Refactor kvm_mmu_alloc_shadow_page() to receive the caches from which it
will allocate the various pieces of memory for shadow pages as a
parameter, rather than deriving them from the vcpu pointer. This will be
useful in a future commit where shadow pages are allocated during VM
ioctls for eager page splitting, and thus will use a different set of
caches.
Preemptively pull the caches out all the way to
kvm_mmu_get_shadow_page() since eager page splitting will not be calling
kvm_mmu_alloc_shadow_page() directly.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 36 +++++++++++++++++++++++++++++-------
1 file changed, 29 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 16001b019e1a..44431c0b797f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2075,17 +2075,25 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
return sp;
}
+/* Caches used when allocating a new shadow page. */
+struct shadow_page_caches {
+ struct kvm_mmu_memory_cache *page_header_cache;
+ struct kvm_mmu_memory_cache *shadow_page_cache;
+ struct kvm_mmu_memory_cache *gfn_array_cache;
+};
+
static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
+ struct shadow_page_caches *caches,
gfn_t gfn,
struct hlist_head *sp_list,
union kvm_mmu_page_role role)
{
struct kvm_mmu_page *sp;
- sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
- sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
+ sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache);
+ sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache);
if (!role.direct)
- sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
+ sp->gfns = kvm_mmu_memory_cache_alloc(caches->gfn_array_cache);
set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
@@ -2107,9 +2115,10 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
return sp;
}
-static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
- gfn_t gfn,
- union kvm_mmu_page_role role)
+static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+ struct shadow_page_caches *caches,
+ gfn_t gfn,
+ union kvm_mmu_page_role role)
{
struct hlist_head *sp_list;
struct kvm_mmu_page *sp;
@@ -2120,13 +2129,26 @@ static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
if (!sp) {
created = true;
- sp = kvm_mmu_alloc_shadow_page(vcpu, gfn, sp_list, role);
+ sp = kvm_mmu_alloc_shadow_page(vcpu, caches, gfn, sp_list, role);
}
trace_kvm_mmu_get_page(sp, created);
return sp;
}
+static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+ gfn_t gfn,
+ union kvm_mmu_page_role role)
+{
+ struct shadow_page_caches caches = {
+ .page_header_cache = &vcpu->arch.mmu_page_header_cache,
+ .shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache,
+ .gfn_array_cache = &vcpu->arch.mmu_gfn_array_cache,
+ };
+
+ return __kvm_mmu_get_shadow_page(vcpu, &caches, gfn, role);
+}
+
static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, u32 access)
{
struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep);
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 09/21] KVM: x86/mmu: Pass memory caches to allocate SPs separately
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Refactor kvm_mmu_alloc_shadow_page() to receive the caches from which it
will allocate the various pieces of memory for shadow pages as a
parameter, rather than deriving them from the vcpu pointer. This will be
useful in a future commit where shadow pages are allocated during VM
ioctls for eager page splitting, and thus will use a different set of
caches.
Preemptively pull the caches out all the way to
kvm_mmu_get_shadow_page() since eager page splitting will not be calling
kvm_mmu_alloc_shadow_page() directly.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 36 +++++++++++++++++++++++++++++-------
1 file changed, 29 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 16001b019e1a..44431c0b797f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2075,17 +2075,25 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
return sp;
}
+/* Caches used when allocating a new shadow page. */
+struct shadow_page_caches {
+ struct kvm_mmu_memory_cache *page_header_cache;
+ struct kvm_mmu_memory_cache *shadow_page_cache;
+ struct kvm_mmu_memory_cache *gfn_array_cache;
+};
+
static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
+ struct shadow_page_caches *caches,
gfn_t gfn,
struct hlist_head *sp_list,
union kvm_mmu_page_role role)
{
struct kvm_mmu_page *sp;
- sp = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_page_header_cache);
- sp->spt = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_shadow_page_cache);
+ sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache);
+ sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache);
if (!role.direct)
- sp->gfns = kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_gfn_array_cache);
+ sp->gfns = kvm_mmu_memory_cache_alloc(caches->gfn_array_cache);
set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
@@ -2107,9 +2115,10 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
return sp;
}
-static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
- gfn_t gfn,
- union kvm_mmu_page_role role)
+static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+ struct shadow_page_caches *caches,
+ gfn_t gfn,
+ union kvm_mmu_page_role role)
{
struct hlist_head *sp_list;
struct kvm_mmu_page *sp;
@@ -2120,13 +2129,26 @@ static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
if (!sp) {
created = true;
- sp = kvm_mmu_alloc_shadow_page(vcpu, gfn, sp_list, role);
+ sp = kvm_mmu_alloc_shadow_page(vcpu, caches, gfn, sp_list, role);
}
trace_kvm_mmu_get_page(sp, created);
return sp;
}
+static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+ gfn_t gfn,
+ union kvm_mmu_page_role role)
+{
+ struct shadow_page_caches caches = {
+ .page_header_cache = &vcpu->arch.mmu_page_header_cache,
+ .shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache,
+ .gfn_array_cache = &vcpu->arch.mmu_gfn_array_cache,
+ };
+
+ return __kvm_mmu_get_shadow_page(vcpu, &caches, gfn, role);
+}
+
static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, u32 access)
{
struct kvm_mmu_page *parent_sp = sptep_to_sp(sptep);
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 10/21] KVM: x86/mmu: Replace vcpu with kvm in kvm_mmu_alloc_shadow_page()
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
The vcpu pointer in kvm_mmu_alloc_shadow_page() is only used to get the
kvm pointer. So drop the vcpu pointer and just pass in the kvm pointer.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 44431c0b797f..9cc73c3453c3 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2082,7 +2082,7 @@ struct shadow_page_caches {
struct kvm_mmu_memory_cache *gfn_array_cache;
};
-static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
struct shadow_page_caches *caches,
gfn_t gfn,
struct hlist_head *sp_list,
@@ -2102,15 +2102,15 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
* depends on valid pages being added to the head of the list. See
* comments in kvm_zap_obsolete_pages().
*/
- sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
- list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
- kvm_mod_used_mmu_pages(vcpu->kvm, +1);
+ sp->mmu_valid_gen = kvm->arch.mmu_valid_gen;
+ list_add(&sp->link, &kvm->arch.active_mmu_pages);
+ kvm_mod_used_mmu_pages(kvm, +1);
sp->gfn = gfn;
sp->role = role;
hlist_add_head(&sp->hash_link, sp_list);
if (sp_has_gptes(sp))
- account_shadowed(vcpu->kvm, sp);
+ account_shadowed(kvm, sp);
return sp;
}
@@ -2129,7 +2129,7 @@ static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
if (!sp) {
created = true;
- sp = kvm_mmu_alloc_shadow_page(vcpu, caches, gfn, sp_list, role);
+ sp = kvm_mmu_alloc_shadow_page(vcpu->kvm, caches, gfn, sp_list, role);
}
trace_kvm_mmu_get_page(sp, created);
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 10/21] KVM: x86/mmu: Replace vcpu with kvm in kvm_mmu_alloc_shadow_page()
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
The vcpu pointer in kvm_mmu_alloc_shadow_page() is only used to get the
kvm pointer. So drop the vcpu pointer and just pass in the kvm pointer.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 44431c0b797f..9cc73c3453c3 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2082,7 +2082,7 @@ struct shadow_page_caches {
struct kvm_mmu_memory_cache *gfn_array_cache;
};
-static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
struct shadow_page_caches *caches,
gfn_t gfn,
struct hlist_head *sp_list,
@@ -2102,15 +2102,15 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm_vcpu *vcpu,
* depends on valid pages being added to the head of the list. See
* comments in kvm_zap_obsolete_pages().
*/
- sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
- list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
- kvm_mod_used_mmu_pages(vcpu->kvm, +1);
+ sp->mmu_valid_gen = kvm->arch.mmu_valid_gen;
+ list_add(&sp->link, &kvm->arch.active_mmu_pages);
+ kvm_mod_used_mmu_pages(kvm, +1);
sp->gfn = gfn;
sp->role = role;
hlist_add_head(&sp->hash_link, sp_list);
if (sp_has_gptes(sp))
- account_shadowed(vcpu->kvm, sp);
+ account_shadowed(kvm, sp);
return sp;
}
@@ -2129,7 +2129,7 @@ static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
if (!sp) {
created = true;
- sp = kvm_mmu_alloc_shadow_page(vcpu, caches, gfn, sp_list, role);
+ sp = kvm_mmu_alloc_shadow_page(vcpu->kvm, caches, gfn, sp_list, role);
}
trace_kvm_mmu_get_page(sp, created);
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 11/21] KVM: x86/mmu: Pass kvm pointer separately from vcpu to kvm_mmu_find_shadow_page()
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Get the kvm pointer from the caller, rather than deriving it from
vcpu->kvm, and plumb the kvm pointer all the way from
kvm_mmu_get_shadow_page(). With this change in place, the vcpu pointer
is only needed to sync indirect shadow pages. In other words,
__kvm_mmu_get_shadow_page() can now be used to get *direct* shadow pages
without a vcpu pointer. This enables eager page splitting, which needs
to allocate direct shadow pages during VM ioctls.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 9cc73c3453c3..cf27c5de9dc0 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2001,7 +2001,8 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sptep_to_sp(spte));
}
-static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
+ struct kvm_vcpu *vcpu,
gfn_t gfn,
struct hlist_head *sp_list,
union kvm_mmu_page_role role)
@@ -2011,7 +2012,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
int collisions = 0;
LIST_HEAD(invalid_list);
- for_each_valid_sp(vcpu->kvm, sp, sp_list) {
+ for_each_valid_sp(kvm, sp, sp_list) {
if (sp->gfn != gfn) {
collisions++;
continue;
@@ -2028,7 +2029,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
* upper-level page will be write-protected.
*/
if (role.level > PG_LEVEL_4K && sp->unsync)
- kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
+ kvm_mmu_prepare_zap_page(kvm, sp,
&invalid_list);
continue;
}
@@ -2056,7 +2057,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
WARN_ON(!list_empty(&invalid_list));
if (ret > 0)
- kvm_flush_remote_tlbs(vcpu->kvm);
+ kvm_flush_remote_tlbs(kvm);
}
__clear_sp_write_flooding_count(sp);
@@ -2065,13 +2066,13 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
}
sp = NULL;
- ++vcpu->kvm->stat.mmu_cache_miss;
+ ++kvm->stat.mmu_cache_miss;
out:
- kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
+ kvm_mmu_commit_zap_page(kvm, &invalid_list);
- if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
- vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
+ if (collisions > kvm->stat.max_mmu_page_hash_collisions)
+ kvm->stat.max_mmu_page_hash_collisions = collisions;
return sp;
}
@@ -2115,7 +2116,8 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
return sp;
}
-static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm,
+ struct kvm_vcpu *vcpu,
struct shadow_page_caches *caches,
gfn_t gfn,
union kvm_mmu_page_role role)
@@ -2124,12 +2126,12 @@ static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp;
bool created = false;
- sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
+ sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
- sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
+ sp = kvm_mmu_find_shadow_page(kvm, vcpu, gfn, sp_list, role);
if (!sp) {
created = true;
- sp = kvm_mmu_alloc_shadow_page(vcpu->kvm, caches, gfn, sp_list, role);
+ sp = kvm_mmu_alloc_shadow_page(kvm, caches, gfn, sp_list, role);
}
trace_kvm_mmu_get_page(sp, created);
@@ -2146,7 +2148,7 @@ static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
.gfn_array_cache = &vcpu->arch.mmu_gfn_array_cache,
};
- return __kvm_mmu_get_shadow_page(vcpu, &caches, gfn, role);
+ return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role);
}
static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, u32 access)
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 11/21] KVM: x86/mmu: Pass kvm pointer separately from vcpu to kvm_mmu_find_shadow_page()
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Get the kvm pointer from the caller, rather than deriving it from
vcpu->kvm, and plumb the kvm pointer all the way from
kvm_mmu_get_shadow_page(). With this change in place, the vcpu pointer
is only needed to sync indirect shadow pages. In other words,
__kvm_mmu_get_shadow_page() can now be used to get *direct* shadow pages
without a vcpu pointer. This enables eager page splitting, which needs
to allocate direct shadow pages during VM ioctls.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 28 +++++++++++++++-------------
1 file changed, 15 insertions(+), 13 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 9cc73c3453c3..cf27c5de9dc0 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -2001,7 +2001,8 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sptep_to_sp(spte));
}
-static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
+ struct kvm_vcpu *vcpu,
gfn_t gfn,
struct hlist_head *sp_list,
union kvm_mmu_page_role role)
@@ -2011,7 +2012,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
int collisions = 0;
LIST_HEAD(invalid_list);
- for_each_valid_sp(vcpu->kvm, sp, sp_list) {
+ for_each_valid_sp(kvm, sp, sp_list) {
if (sp->gfn != gfn) {
collisions++;
continue;
@@ -2028,7 +2029,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
* upper-level page will be write-protected.
*/
if (role.level > PG_LEVEL_4K && sp->unsync)
- kvm_mmu_prepare_zap_page(vcpu->kvm, sp,
+ kvm_mmu_prepare_zap_page(kvm, sp,
&invalid_list);
continue;
}
@@ -2056,7 +2057,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
WARN_ON(!list_empty(&invalid_list));
if (ret > 0)
- kvm_flush_remote_tlbs(vcpu->kvm);
+ kvm_flush_remote_tlbs(kvm);
}
__clear_sp_write_flooding_count(sp);
@@ -2065,13 +2066,13 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm_vcpu *vcpu,
}
sp = NULL;
- ++vcpu->kvm->stat.mmu_cache_miss;
+ ++kvm->stat.mmu_cache_miss;
out:
- kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
+ kvm_mmu_commit_zap_page(kvm, &invalid_list);
- if (collisions > vcpu->kvm->stat.max_mmu_page_hash_collisions)
- vcpu->kvm->stat.max_mmu_page_hash_collisions = collisions;
+ if (collisions > kvm->stat.max_mmu_page_hash_collisions)
+ kvm->stat.max_mmu_page_hash_collisions = collisions;
return sp;
}
@@ -2115,7 +2116,8 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
return sp;
}
-static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
+static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm,
+ struct kvm_vcpu *vcpu,
struct shadow_page_caches *caches,
gfn_t gfn,
union kvm_mmu_page_role role)
@@ -2124,12 +2126,12 @@ static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
struct kvm_mmu_page *sp;
bool created = false;
- sp_list = &vcpu->kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
+ sp_list = &kvm->arch.mmu_page_hash[kvm_page_table_hashfn(gfn)];
- sp = kvm_mmu_find_shadow_page(vcpu, gfn, sp_list, role);
+ sp = kvm_mmu_find_shadow_page(kvm, vcpu, gfn, sp_list, role);
if (!sp) {
created = true;
- sp = kvm_mmu_alloc_shadow_page(vcpu->kvm, caches, gfn, sp_list, role);
+ sp = kvm_mmu_alloc_shadow_page(kvm, caches, gfn, sp_list, role);
}
trace_kvm_mmu_get_page(sp, created);
@@ -2146,7 +2148,7 @@ static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
.gfn_array_cache = &vcpu->arch.mmu_gfn_array_cache,
};
- return __kvm_mmu_get_shadow_page(vcpu, &caches, gfn, role);
+ return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role);
}
static union kvm_mmu_page_role kvm_mmu_child_role(u64 *sptep, bool direct, u32 access)
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 12/21] KVM: x86/mmu: Allow NULL @vcpu in kvm_mmu_find_shadow_page()
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Allow @vcpu to be NULL in kvm_mmu_find_shadow_page() (and its only
caller __kvm_mmu_get_shadow_page()). @vcpu is only required to sync
indirect shadow pages, so it's safe to pass in NULL when looking up
direct shadow pages.
This will be used for doing eager page splitting, which allocates direct
shadow pages from the context of a VM ioctl without access to a vCPU
pointer.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index cf27c5de9dc0..bc66029d837f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1850,6 +1850,7 @@ static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
if (ret < 0)
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
+
return ret;
}
@@ -2001,6 +2002,7 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sptep_to_sp(spte));
}
+/* Note, @vcpu may be NULL if @role.direct is true. */
static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
struct kvm_vcpu *vcpu,
gfn_t gfn,
@@ -2039,6 +2041,16 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
goto out;
if (sp->unsync) {
+ /*
+ * A vCPU pointer should always be provided when finding
+ * indirect shadow pages, as that shadow page may
+ * already exist and need to be synced using the vCPU
+ * pointer. Direct shadow pages are never unsync and
+ * thus do not require a vCPU pointer.
+ */
+ if (KVM_BUG_ON(!vcpu, kvm))
+ break;
+
/*
* The page is good, but is stale. kvm_sync_page does
* get the latest guest state, but (unlike mmu_unsync_children)
@@ -2116,6 +2128,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
return sp;
}
+/* Note, @vcpu may be NULL if @role.direct is true. */
static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm,
struct kvm_vcpu *vcpu,
struct shadow_page_caches *caches,
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 12/21] KVM: x86/mmu: Allow NULL @vcpu in kvm_mmu_find_shadow_page()
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Allow @vcpu to be NULL in kvm_mmu_find_shadow_page() (and its only
caller __kvm_mmu_get_shadow_page()). @vcpu is only required to sync
indirect shadow pages, so it's safe to pass in NULL when looking up
direct shadow pages.
This will be used for doing eager page splitting, which allocates direct
shadow pages from the context of a VM ioctl without access to a vCPU
pointer.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index cf27c5de9dc0..bc66029d837f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1850,6 +1850,7 @@ static int kvm_sync_page(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
if (ret < 0)
kvm_mmu_prepare_zap_page(vcpu->kvm, sp, invalid_list);
+
return ret;
}
@@ -2001,6 +2002,7 @@ static void clear_sp_write_flooding_count(u64 *spte)
__clear_sp_write_flooding_count(sptep_to_sp(spte));
}
+/* Note, @vcpu may be NULL if @role.direct is true. */
static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
struct kvm_vcpu *vcpu,
gfn_t gfn,
@@ -2039,6 +2041,16 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
goto out;
if (sp->unsync) {
+ /*
+ * A vCPU pointer should always be provided when finding
+ * indirect shadow pages, as that shadow page may
+ * already exist and need to be synced using the vCPU
+ * pointer. Direct shadow pages are never unsync and
+ * thus do not require a vCPU pointer.
+ */
+ if (KVM_BUG_ON(!vcpu, kvm))
+ break;
+
/*
* The page is good, but is stale. kvm_sync_page does
* get the latest guest state, but (unlike mmu_unsync_children)
@@ -2116,6 +2128,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
return sp;
}
+/* Note, @vcpu may be NULL if @role.direct is true. */
static struct kvm_mmu_page *__kvm_mmu_get_shadow_page(struct kvm *kvm,
struct kvm_vcpu *vcpu,
struct shadow_page_caches *caches,
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 13/21] KVM: x86/mmu: Pass const memslot to rmap_add()
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
rmap_add() only uses the slot to call gfn_to_rmap() which takes a const
memslot.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index bc66029d837f..8a6dec1c27c8 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1582,7 +1582,7 @@ static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
#define RMAP_RECYCLE_THRESHOLD 1000
-static void rmap_add(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
+static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
u64 *spte, gfn_t gfn)
{
struct kvm_mmu_page *sp;
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 13/21] KVM: x86/mmu: Pass const memslot to rmap_add()
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
rmap_add() only uses the slot to call gfn_to_rmap() which takes a const
memslot.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index bc66029d837f..8a6dec1c27c8 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1582,7 +1582,7 @@ static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
#define RMAP_RECYCLE_THRESHOLD 1000
-static void rmap_add(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
+static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
u64 *spte, gfn_t gfn)
{
struct kvm_mmu_page *sp;
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 14/21] KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Allow adding new entries to the rmap and linking shadow pages without a
struct kvm_vcpu pointer by moving the implementation of rmap_add() and
link_shadow_page() into inner helper functions.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 45 +++++++++++++++++++++++++-----------------
1 file changed, 27 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 8a6dec1c27c8..0a14320fb148 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -699,11 +699,6 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
}
-static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu)
-{
- return kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_list_desc_cache);
-}
-
static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc)
{
kmem_cache_free(pte_list_desc_cache, pte_list_desc);
@@ -858,7 +853,7 @@ gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
/*
* Returns the number of pointers in the rmap chain, not counting the new one.
*/
-static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
+static int pte_list_add(struct kvm_mmu_memory_cache *cache, u64 *spte,
struct kvm_rmap_head *rmap_head)
{
struct pte_list_desc *desc;
@@ -869,7 +864,7 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
rmap_head->val = (unsigned long)spte;
} else if (!(rmap_head->val & 1)) {
rmap_printk("%p %llx 1->many\n", spte, *spte);
- desc = mmu_alloc_pte_list_desc(vcpu);
+ desc = kvm_mmu_memory_cache_alloc(cache);
desc->sptes[0] = (u64 *)rmap_head->val;
desc->sptes[1] = spte;
desc->spte_count = 2;
@@ -881,7 +876,7 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
while (desc->spte_count == PTE_LIST_EXT) {
count += PTE_LIST_EXT;
if (!desc->more) {
- desc->more = mmu_alloc_pte_list_desc(vcpu);
+ desc->more = kvm_mmu_memory_cache_alloc(cache);
desc = desc->more;
desc->spte_count = 0;
break;
@@ -1582,8 +1577,10 @@ static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
#define RMAP_RECYCLE_THRESHOLD 1000
-static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
- u64 *spte, gfn_t gfn)
+static void __rmap_add(struct kvm *kvm,
+ struct kvm_mmu_memory_cache *cache,
+ const struct kvm_memory_slot *slot,
+ u64 *spte, gfn_t gfn)
{
struct kvm_mmu_page *sp;
struct kvm_rmap_head *rmap_head;
@@ -1592,15 +1589,21 @@ static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
sp = sptep_to_sp(spte);
kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
- rmap_count = pte_list_add(vcpu, spte, rmap_head);
+ rmap_count = pte_list_add(cache, spte, rmap_head);
if (rmap_count > RMAP_RECYCLE_THRESHOLD) {
- kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
+ kvm_unmap_rmapp(kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
kvm_flush_remote_tlbs_with_address(
- vcpu->kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
+ kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
}
}
+static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
+ u64 *spte, gfn_t gfn)
+{
+ __rmap_add(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, slot, spte, gfn);
+}
+
bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
{
bool young = false;
@@ -1671,13 +1674,13 @@ static unsigned kvm_page_table_hashfn(gfn_t gfn)
return hash_64(gfn, KVM_MMU_HASH_SHIFT);
}
-static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
+static void mmu_page_add_parent_pte(struct kvm_mmu_memory_cache *cache,
struct kvm_mmu_page *sp, u64 *parent_pte)
{
if (!parent_pte)
return;
- pte_list_add(vcpu, parent_pte, &sp->parent_ptes);
+ pte_list_add(cache, parent_pte, &sp->parent_ptes);
}
static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp,
@@ -2276,8 +2279,8 @@ static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
__shadow_walk_next(iterator, *iterator->sptep);
}
-static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
- struct kvm_mmu_page *sp)
+static void __link_shadow_page(struct kvm_mmu_memory_cache *cache, u64 *sptep,
+ struct kvm_mmu_page *sp)
{
u64 spte;
@@ -2287,12 +2290,18 @@ static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
mmu_spte_set(sptep, spte);
- mmu_page_add_parent_pte(vcpu, sp, sptep);
+ mmu_page_add_parent_pte(cache, sp, sptep);
if (sp->unsync_children || sp->unsync)
mark_unsync(sptep);
}
+static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
+ struct kvm_mmu_page *sp)
+{
+ __link_shadow_page(&vcpu->arch.mmu_pte_list_desc_cache, sptep, sp);
+}
+
static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
unsigned direct_access)
{
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 14/21] KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Allow adding new entries to the rmap and linking shadow pages without a
struct kvm_vcpu pointer by moving the implementation of rmap_add() and
link_shadow_page() into inner helper functions.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 45 +++++++++++++++++++++++++-----------------
1 file changed, 27 insertions(+), 18 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 8a6dec1c27c8..0a14320fb148 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -699,11 +699,6 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
}
-static struct pte_list_desc *mmu_alloc_pte_list_desc(struct kvm_vcpu *vcpu)
-{
- return kvm_mmu_memory_cache_alloc(&vcpu->arch.mmu_pte_list_desc_cache);
-}
-
static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc)
{
kmem_cache_free(pte_list_desc_cache, pte_list_desc);
@@ -858,7 +853,7 @@ gfn_to_memslot_dirty_bitmap(struct kvm_vcpu *vcpu, gfn_t gfn,
/*
* Returns the number of pointers in the rmap chain, not counting the new one.
*/
-static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
+static int pte_list_add(struct kvm_mmu_memory_cache *cache, u64 *spte,
struct kvm_rmap_head *rmap_head)
{
struct pte_list_desc *desc;
@@ -869,7 +864,7 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
rmap_head->val = (unsigned long)spte;
} else if (!(rmap_head->val & 1)) {
rmap_printk("%p %llx 1->many\n", spte, *spte);
- desc = mmu_alloc_pte_list_desc(vcpu);
+ desc = kvm_mmu_memory_cache_alloc(cache);
desc->sptes[0] = (u64 *)rmap_head->val;
desc->sptes[1] = spte;
desc->spte_count = 2;
@@ -881,7 +876,7 @@ static int pte_list_add(struct kvm_vcpu *vcpu, u64 *spte,
while (desc->spte_count == PTE_LIST_EXT) {
count += PTE_LIST_EXT;
if (!desc->more) {
- desc->more = mmu_alloc_pte_list_desc(vcpu);
+ desc->more = kvm_mmu_memory_cache_alloc(cache);
desc = desc->more;
desc->spte_count = 0;
break;
@@ -1582,8 +1577,10 @@ static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
#define RMAP_RECYCLE_THRESHOLD 1000
-static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
- u64 *spte, gfn_t gfn)
+static void __rmap_add(struct kvm *kvm,
+ struct kvm_mmu_memory_cache *cache,
+ const struct kvm_memory_slot *slot,
+ u64 *spte, gfn_t gfn)
{
struct kvm_mmu_page *sp;
struct kvm_rmap_head *rmap_head;
@@ -1592,15 +1589,21 @@ static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
sp = sptep_to_sp(spte);
kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
- rmap_count = pte_list_add(vcpu, spte, rmap_head);
+ rmap_count = pte_list_add(cache, spte, rmap_head);
if (rmap_count > RMAP_RECYCLE_THRESHOLD) {
- kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
+ kvm_unmap_rmapp(kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
kvm_flush_remote_tlbs_with_address(
- vcpu->kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
+ kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
}
}
+static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
+ u64 *spte, gfn_t gfn)
+{
+ __rmap_add(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, slot, spte, gfn);
+}
+
bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
{
bool young = false;
@@ -1671,13 +1674,13 @@ static unsigned kvm_page_table_hashfn(gfn_t gfn)
return hash_64(gfn, KVM_MMU_HASH_SHIFT);
}
-static void mmu_page_add_parent_pte(struct kvm_vcpu *vcpu,
+static void mmu_page_add_parent_pte(struct kvm_mmu_memory_cache *cache,
struct kvm_mmu_page *sp, u64 *parent_pte)
{
if (!parent_pte)
return;
- pte_list_add(vcpu, parent_pte, &sp->parent_ptes);
+ pte_list_add(cache, parent_pte, &sp->parent_ptes);
}
static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp,
@@ -2276,8 +2279,8 @@ static void shadow_walk_next(struct kvm_shadow_walk_iterator *iterator)
__shadow_walk_next(iterator, *iterator->sptep);
}
-static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
- struct kvm_mmu_page *sp)
+static void __link_shadow_page(struct kvm_mmu_memory_cache *cache, u64 *sptep,
+ struct kvm_mmu_page *sp)
{
u64 spte;
@@ -2287,12 +2290,18 @@ static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
mmu_spte_set(sptep, spte);
- mmu_page_add_parent_pte(vcpu, sp, sptep);
+ mmu_page_add_parent_pte(cache, sp, sptep);
if (sp->unsync_children || sp->unsync)
mark_unsync(sptep);
}
+static void link_shadow_page(struct kvm_vcpu *vcpu, u64 *sptep,
+ struct kvm_mmu_page *sp)
+{
+ __link_shadow_page(&vcpu->arch.mmu_pte_list_desc_cache, sptep, sp);
+}
+
static void validate_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep,
unsigned direct_access)
{
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 15/21] KVM: x86/mmu: Update page stats in __rmap_add()
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Update the page stats in __rmap_add() rather than at the call site. This
will avoid having to manually update page stats when splitting huge
pages in a subsequent commit.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 0a14320fb148..c7cc552440f7 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1588,6 +1588,8 @@ static void __rmap_add(struct kvm *kvm,
sp = sptep_to_sp(spte);
kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
+ kvm_update_page_stats(kvm, sp->role.level, 1);
+
rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
rmap_count = pte_list_add(cache, spte, rmap_head);
@@ -2810,7 +2812,6 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
if (!was_rmapped) {
WARN_ON_ONCE(ret == RET_PF_SPURIOUS);
- kvm_update_page_stats(vcpu->kvm, level, 1);
rmap_add(vcpu, slot, sptep, gfn);
}
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 15/21] KVM: x86/mmu: Update page stats in __rmap_add()
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Update the page stats in __rmap_add() rather than at the call site. This
will avoid having to manually update page stats when splitting huge
pages in a subsequent commit.
No functional change intended.
Reviewed-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 0a14320fb148..c7cc552440f7 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1588,6 +1588,8 @@ static void __rmap_add(struct kvm *kvm,
sp = sptep_to_sp(spte);
kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
+ kvm_update_page_stats(kvm, sp->role.level, 1);
+
rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
rmap_count = pte_list_add(cache, spte, rmap_head);
@@ -2810,7 +2812,6 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
if (!was_rmapped) {
WARN_ON_ONCE(ret == RET_PF_SPURIOUS);
- kvm_update_page_stats(vcpu->kvm, level, 1);
rmap_add(vcpu, slot, sptep, gfn);
}
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 16/21] KVM: x86/mmu: Cache the access bits of shadowed translations
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Splitting huge pages requires allocating/finding shadow pages to replace
the huge page. Shadow pages are keyed, in part, off the guest access
permissions they are shadowing. For fully direct MMUs, there is no
shadowing so the access bits in the shadow page role are always ACC_ALL.
But during shadow paging, the guest can enforce whatever access
permissions it wants.
When KVM is resolving a fault, it walks the guest pages tables to
determine the guest access permissions. But that is difficult to plumb
when splitting huge pages outside of a fault context, e.g. for eager
page splitting.
To enable eager page splitting, KVM can cache the shadowed (guest)
access permissions whenever it updates the shadow page tables (e.g.
during fault, or FNAME(sync_page)). In fact KVM already does this to
cache the shadowed GFN using the gfns array in the shadow page.
The access bits only take up 3 bits, which leaves 61 bits left over for
gfns, which is more than enough. So this change does not require any
additional memory.
Now that the gfns array caches more information than just GFNs, rename
it to shadowed_translation.
While here, preemptively fix up the WARN_ON() that detects gfn
mismatches in direct SPs. The WARN_ON() was paired with a
pr_err_ratelimited(), which means that users could sometimes see the
WARN without the accompanying error message. Fix this by outputting the
error message as part of the WARN splat.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/mmu/mmu.c | 85 +++++++++++++++++++++++----------
arch/x86/kvm/mmu/mmu_internal.h | 17 ++++++-
arch/x86/kvm/mmu/paging_tmpl.h | 8 +++-
4 files changed, 83 insertions(+), 29 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9cdc5bbd721f..9193a700fe2d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -710,7 +710,7 @@ struct kvm_vcpu_arch {
struct kvm_mmu_memory_cache mmu_pte_list_desc_cache;
struct kvm_mmu_memory_cache mmu_shadow_page_cache;
- struct kvm_mmu_memory_cache mmu_gfn_array_cache;
+ struct kvm_mmu_memory_cache mmu_shadowed_info_cache;
struct kvm_mmu_memory_cache mmu_page_header_cache;
/*
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c7cc552440f7..b411b0d202c8 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -682,7 +682,7 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
if (r)
return r;
if (maybe_indirect) {
- r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_gfn_array_cache,
+ r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadowed_info_cache,
PT64_ROOT_MAX_LEVEL);
if (r)
return r;
@@ -695,7 +695,7 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache);
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache);
- kvm_mmu_free_memory_cache(&vcpu->arch.mmu_gfn_array_cache);
+ kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadowed_info_cache);
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
}
@@ -704,34 +704,68 @@ static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc)
kmem_cache_free(pte_list_desc_cache, pte_list_desc);
}
+static bool sp_has_gptes(struct kvm_mmu_page *sp);
+
static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index)
{
if (sp->role.passthrough)
return sp->gfn;
if (!sp->role.direct)
- return sp->gfns[index];
+ return sp->shadowed_translation[index] >> PAGE_SHIFT;
return sp->gfn + (index << ((sp->role.level - 1) * PT64_LEVEL_BITS));
}
-static void kvm_mmu_page_set_gfn(struct kvm_mmu_page *sp, int index, gfn_t gfn)
+/*
+ * For leaf SPTEs, fetch the *guest* access permissions being shadowed. Note
+ * that the SPTE itself may have a more constrained access permissions that
+ * what the guest enforces. For example, a guest may create an executable
+ * huge PTE but KVM may disallow execution to mitigate iTLB multihit.
+ */
+static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index)
{
- if (sp->role.passthrough) {
- WARN_ON_ONCE(gfn != sp->gfn);
- return;
- }
+ if (sp_has_gptes(sp))
+ return sp->shadowed_translation[index] & ACC_ALL;
- if (!sp->role.direct) {
- sp->gfns[index] = gfn;
+ /*
+ * For direct MMUs (e.g. TDP or non-paging guests) or passthrough SPs,
+ * KVM is not shadowing any guest page tables, so the "guest access
+ * permissions" are just ACC_ALL.
+ *
+ * For direct SPs in indirect MMUs (shadow paging), i.e. when KVM
+ * is shadowing a guest huge page with small pages, the guest access
+ * permissions being shadowed are the access permissions of the huge
+ * page.
+ *
+ * In both cases, sp->role.access contains the correct access bits.
+ */
+ return sp->role.access;
+}
+
+static void kvm_mmu_page_set_translation(struct kvm_mmu_page *sp, int index, gfn_t gfn, u32 access)
+{
+ if (sp_has_gptes(sp)) {
+ sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access;
return;
}
- if (WARN_ON(gfn != kvm_mmu_page_get_gfn(sp, index)))
- pr_err_ratelimited("gfn mismatch under direct page %llx "
- "(expected %llx, got %llx)\n",
- sp->gfn,
- kvm_mmu_page_get_gfn(sp, index), gfn);
+ WARN(access != kvm_mmu_page_get_access(sp, index),
+ "access mismatch under %s page %llx (expected %u, got %u)\n",
+ sp->role.passthrough ? "passthrough" : "direct",
+ sp->gfn, kvm_mmu_page_get_access(sp, index), access);
+
+ WARN(gfn != kvm_mmu_page_get_gfn(sp, index),
+ "gfn mismatch under %s page %llx (expected %llx, got %llx)\n",
+ sp->role.passthrough ? "passthrough" : "direct",
+ sp->gfn, kvm_mmu_page_get_gfn(sp, index), gfn);
+}
+
+static void kvm_mmu_page_set_access(struct kvm_mmu_page *sp, int index, u32 access)
+{
+ gfn_t gfn = kvm_mmu_page_get_gfn(sp, index);
+
+ kvm_mmu_page_set_translation(sp, index, gfn, access);
}
/*
@@ -1580,14 +1614,14 @@ static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
static void __rmap_add(struct kvm *kvm,
struct kvm_mmu_memory_cache *cache,
const struct kvm_memory_slot *slot,
- u64 *spte, gfn_t gfn)
+ u64 *spte, gfn_t gfn, u32 access)
{
struct kvm_mmu_page *sp;
struct kvm_rmap_head *rmap_head;
int rmap_count;
sp = sptep_to_sp(spte);
- kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
+ kvm_mmu_page_set_translation(sp, spte - sp->spt, gfn, access);
kvm_update_page_stats(kvm, sp->role.level, 1);
rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
@@ -1601,9 +1635,9 @@ static void __rmap_add(struct kvm *kvm,
}
static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
- u64 *spte, gfn_t gfn)
+ u64 *spte, gfn_t gfn, u32 access)
{
- __rmap_add(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, slot, spte, gfn);
+ __rmap_add(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, slot, spte, gfn, access);
}
bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
@@ -1667,7 +1701,7 @@ static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp)
list_del(&sp->link);
free_page((unsigned long)sp->spt);
if (!sp->role.direct)
- free_page((unsigned long)sp->gfns);
+ free_page((unsigned long)sp->shadowed_translation);
kmem_cache_free(mmu_page_header_cache, sp);
}
@@ -2097,7 +2131,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
struct shadow_page_caches {
struct kvm_mmu_memory_cache *page_header_cache;
struct kvm_mmu_memory_cache *shadow_page_cache;
- struct kvm_mmu_memory_cache *gfn_array_cache;
+ struct kvm_mmu_memory_cache *shadowed_info_cache;
};
static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
@@ -2111,7 +2145,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache);
sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache);
if (!role.direct)
- sp->gfns = kvm_mmu_memory_cache_alloc(caches->gfn_array_cache);
+ sp->shadowed_translation = kvm_mmu_memory_cache_alloc(caches->shadowed_info_cache);
set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
@@ -2163,7 +2197,7 @@ static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
struct shadow_page_caches caches = {
.page_header_cache = &vcpu->arch.mmu_page_header_cache,
.shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache,
- .gfn_array_cache = &vcpu->arch.mmu_gfn_array_cache,
+ .shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache,
};
return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role);
@@ -2812,7 +2846,10 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
if (!was_rmapped) {
WARN_ON_ONCE(ret == RET_PF_SPURIOUS);
- rmap_add(vcpu, slot, sptep, gfn);
+ rmap_add(vcpu, slot, sptep, gfn, pte_access);
+ } else {
+ /* Already rmapped but the pte_access bits may have changed. */
+ kvm_mmu_page_set_access(sp, sptep - sp->spt, pte_access);
}
return ret;
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index bd2a26897b97..0395950045d1 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -53,8 +53,21 @@ struct kvm_mmu_page {
gfn_t gfn;
u64 *spt;
- /* hold the gfn of each spte inside spt */
- gfn_t *gfns;
+
+ /*
+ * Stores the result of the guest translation being shadowed by each
+ * SPTE. KVM shadows two types of guest translations: nGPA -> GPA
+ * (shadow EPT/NPT) and GVA -> GPA (traditional shadow paging). In both
+ * cases the result of the translation is a GPA and a set of access
+ * constraints.
+ *
+ * The GFN is stored in the upper bits (PAGE_SHIFT) and the shadowed
+ * access permissions are stored in the lower bits. Note, for
+ * convenience and uniformity across guests, the access permissions are
+ * stored in KVM format (e.g. ACC_EXEC_MASK) not the raw guest format.
+ */
+ u64 *shadowed_translation;
+
/* Currently serving as active root */
union {
int root_count;
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index fd73c857af90..37ceb6e452e6 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -979,7 +979,8 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
}
/*
- * Using the cached information from sp->gfns is safe because:
+ * Using the information in sp->shadowed_translation (kvm_mmu_page_get_gfn()) is
+ * safe because:
* - The spte has a reference to the struct page, so the pfn for a given gfn
* can't change unless all sptes pointing to it are nuked first.
*
@@ -1054,12 +1055,15 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
if (sync_mmio_spte(vcpu, &sp->spt[i], gfn, pte_access))
continue;
- if (gfn != sp->gfns[i]) {
+ if (gfn != kvm_mmu_page_get_gfn(sp, i)) {
drop_spte(vcpu->kvm, &sp->spt[i]);
flush = true;
continue;
}
+ /* Update the shadowed access bits in case they changed. */
+ kvm_mmu_page_set_access(sp, i, pte_access);
+
sptep = &sp->spt[i];
spte = *sptep;
host_writable = spte & shadow_host_writable_mask;
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 16/21] KVM: x86/mmu: Cache the access bits of shadowed translations
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Splitting huge pages requires allocating/finding shadow pages to replace
the huge page. Shadow pages are keyed, in part, off the guest access
permissions they are shadowing. For fully direct MMUs, there is no
shadowing so the access bits in the shadow page role are always ACC_ALL.
But during shadow paging, the guest can enforce whatever access
permissions it wants.
When KVM is resolving a fault, it walks the guest pages tables to
determine the guest access permissions. But that is difficult to plumb
when splitting huge pages outside of a fault context, e.g. for eager
page splitting.
To enable eager page splitting, KVM can cache the shadowed (guest)
access permissions whenever it updates the shadow page tables (e.g.
during fault, or FNAME(sync_page)). In fact KVM already does this to
cache the shadowed GFN using the gfns array in the shadow page.
The access bits only take up 3 bits, which leaves 61 bits left over for
gfns, which is more than enough. So this change does not require any
additional memory.
Now that the gfns array caches more information than just GFNs, rename
it to shadowed_translation.
While here, preemptively fix up the WARN_ON() that detects gfn
mismatches in direct SPs. The WARN_ON() was paired with a
pr_err_ratelimited(), which means that users could sometimes see the
WARN without the accompanying error message. Fix this by outputting the
error message as part of the WARN splat.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/include/asm/kvm_host.h | 2 +-
arch/x86/kvm/mmu/mmu.c | 85 +++++++++++++++++++++++----------
arch/x86/kvm/mmu/mmu_internal.h | 17 ++++++-
arch/x86/kvm/mmu/paging_tmpl.h | 8 +++-
4 files changed, 83 insertions(+), 29 deletions(-)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9cdc5bbd721f..9193a700fe2d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -710,7 +710,7 @@ struct kvm_vcpu_arch {
struct kvm_mmu_memory_cache mmu_pte_list_desc_cache;
struct kvm_mmu_memory_cache mmu_shadow_page_cache;
- struct kvm_mmu_memory_cache mmu_gfn_array_cache;
+ struct kvm_mmu_memory_cache mmu_shadowed_info_cache;
struct kvm_mmu_memory_cache mmu_page_header_cache;
/*
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c7cc552440f7..b411b0d202c8 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -682,7 +682,7 @@ static int mmu_topup_memory_caches(struct kvm_vcpu *vcpu, bool maybe_indirect)
if (r)
return r;
if (maybe_indirect) {
- r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_gfn_array_cache,
+ r = kvm_mmu_topup_memory_cache(&vcpu->arch.mmu_shadowed_info_cache,
PT64_ROOT_MAX_LEVEL);
if (r)
return r;
@@ -695,7 +695,7 @@ static void mmu_free_memory_caches(struct kvm_vcpu *vcpu)
{
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_pte_list_desc_cache);
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadow_page_cache);
- kvm_mmu_free_memory_cache(&vcpu->arch.mmu_gfn_array_cache);
+ kvm_mmu_free_memory_cache(&vcpu->arch.mmu_shadowed_info_cache);
kvm_mmu_free_memory_cache(&vcpu->arch.mmu_page_header_cache);
}
@@ -704,34 +704,68 @@ static void mmu_free_pte_list_desc(struct pte_list_desc *pte_list_desc)
kmem_cache_free(pte_list_desc_cache, pte_list_desc);
}
+static bool sp_has_gptes(struct kvm_mmu_page *sp);
+
static gfn_t kvm_mmu_page_get_gfn(struct kvm_mmu_page *sp, int index)
{
if (sp->role.passthrough)
return sp->gfn;
if (!sp->role.direct)
- return sp->gfns[index];
+ return sp->shadowed_translation[index] >> PAGE_SHIFT;
return sp->gfn + (index << ((sp->role.level - 1) * PT64_LEVEL_BITS));
}
-static void kvm_mmu_page_set_gfn(struct kvm_mmu_page *sp, int index, gfn_t gfn)
+/*
+ * For leaf SPTEs, fetch the *guest* access permissions being shadowed. Note
+ * that the SPTE itself may have a more constrained access permissions that
+ * what the guest enforces. For example, a guest may create an executable
+ * huge PTE but KVM may disallow execution to mitigate iTLB multihit.
+ */
+static u32 kvm_mmu_page_get_access(struct kvm_mmu_page *sp, int index)
{
- if (sp->role.passthrough) {
- WARN_ON_ONCE(gfn != sp->gfn);
- return;
- }
+ if (sp_has_gptes(sp))
+ return sp->shadowed_translation[index] & ACC_ALL;
- if (!sp->role.direct) {
- sp->gfns[index] = gfn;
+ /*
+ * For direct MMUs (e.g. TDP or non-paging guests) or passthrough SPs,
+ * KVM is not shadowing any guest page tables, so the "guest access
+ * permissions" are just ACC_ALL.
+ *
+ * For direct SPs in indirect MMUs (shadow paging), i.e. when KVM
+ * is shadowing a guest huge page with small pages, the guest access
+ * permissions being shadowed are the access permissions of the huge
+ * page.
+ *
+ * In both cases, sp->role.access contains the correct access bits.
+ */
+ return sp->role.access;
+}
+
+static void kvm_mmu_page_set_translation(struct kvm_mmu_page *sp, int index, gfn_t gfn, u32 access)
+{
+ if (sp_has_gptes(sp)) {
+ sp->shadowed_translation[index] = (gfn << PAGE_SHIFT) | access;
return;
}
- if (WARN_ON(gfn != kvm_mmu_page_get_gfn(sp, index)))
- pr_err_ratelimited("gfn mismatch under direct page %llx "
- "(expected %llx, got %llx)\n",
- sp->gfn,
- kvm_mmu_page_get_gfn(sp, index), gfn);
+ WARN(access != kvm_mmu_page_get_access(sp, index),
+ "access mismatch under %s page %llx (expected %u, got %u)\n",
+ sp->role.passthrough ? "passthrough" : "direct",
+ sp->gfn, kvm_mmu_page_get_access(sp, index), access);
+
+ WARN(gfn != kvm_mmu_page_get_gfn(sp, index),
+ "gfn mismatch under %s page %llx (expected %llx, got %llx)\n",
+ sp->role.passthrough ? "passthrough" : "direct",
+ sp->gfn, kvm_mmu_page_get_gfn(sp, index), gfn);
+}
+
+static void kvm_mmu_page_set_access(struct kvm_mmu_page *sp, int index, u32 access)
+{
+ gfn_t gfn = kvm_mmu_page_get_gfn(sp, index);
+
+ kvm_mmu_page_set_translation(sp, index, gfn, access);
}
/*
@@ -1580,14 +1614,14 @@ static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
static void __rmap_add(struct kvm *kvm,
struct kvm_mmu_memory_cache *cache,
const struct kvm_memory_slot *slot,
- u64 *spte, gfn_t gfn)
+ u64 *spte, gfn_t gfn, u32 access)
{
struct kvm_mmu_page *sp;
struct kvm_rmap_head *rmap_head;
int rmap_count;
sp = sptep_to_sp(spte);
- kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
+ kvm_mmu_page_set_translation(sp, spte - sp->spt, gfn, access);
kvm_update_page_stats(kvm, sp->role.level, 1);
rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
@@ -1601,9 +1635,9 @@ static void __rmap_add(struct kvm *kvm,
}
static void rmap_add(struct kvm_vcpu *vcpu, const struct kvm_memory_slot *slot,
- u64 *spte, gfn_t gfn)
+ u64 *spte, gfn_t gfn, u32 access)
{
- __rmap_add(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, slot, spte, gfn);
+ __rmap_add(vcpu->kvm, &vcpu->arch.mmu_pte_list_desc_cache, slot, spte, gfn, access);
}
bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
@@ -1667,7 +1701,7 @@ static void kvm_mmu_free_shadow_page(struct kvm_mmu_page *sp)
list_del(&sp->link);
free_page((unsigned long)sp->spt);
if (!sp->role.direct)
- free_page((unsigned long)sp->gfns);
+ free_page((unsigned long)sp->shadowed_translation);
kmem_cache_free(mmu_page_header_cache, sp);
}
@@ -2097,7 +2131,7 @@ static struct kvm_mmu_page *kvm_mmu_find_shadow_page(struct kvm *kvm,
struct shadow_page_caches {
struct kvm_mmu_memory_cache *page_header_cache;
struct kvm_mmu_memory_cache *shadow_page_cache;
- struct kvm_mmu_memory_cache *gfn_array_cache;
+ struct kvm_mmu_memory_cache *shadowed_info_cache;
};
static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
@@ -2111,7 +2145,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_shadow_page(struct kvm *kvm,
sp = kvm_mmu_memory_cache_alloc(caches->page_header_cache);
sp->spt = kvm_mmu_memory_cache_alloc(caches->shadow_page_cache);
if (!role.direct)
- sp->gfns = kvm_mmu_memory_cache_alloc(caches->gfn_array_cache);
+ sp->shadowed_translation = kvm_mmu_memory_cache_alloc(caches->shadowed_info_cache);
set_page_private(virt_to_page(sp->spt), (unsigned long)sp);
@@ -2163,7 +2197,7 @@ static struct kvm_mmu_page *kvm_mmu_get_shadow_page(struct kvm_vcpu *vcpu,
struct shadow_page_caches caches = {
.page_header_cache = &vcpu->arch.mmu_page_header_cache,
.shadow_page_cache = &vcpu->arch.mmu_shadow_page_cache,
- .gfn_array_cache = &vcpu->arch.mmu_gfn_array_cache,
+ .shadowed_info_cache = &vcpu->arch.mmu_shadowed_info_cache,
};
return __kvm_mmu_get_shadow_page(vcpu->kvm, vcpu, &caches, gfn, role);
@@ -2812,7 +2846,10 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, struct kvm_memory_slot *slot,
if (!was_rmapped) {
WARN_ON_ONCE(ret == RET_PF_SPURIOUS);
- rmap_add(vcpu, slot, sptep, gfn);
+ rmap_add(vcpu, slot, sptep, gfn, pte_access);
+ } else {
+ /* Already rmapped but the pte_access bits may have changed. */
+ kvm_mmu_page_set_access(sp, sptep - sp->spt, pte_access);
}
return ret;
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index bd2a26897b97..0395950045d1 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -53,8 +53,21 @@ struct kvm_mmu_page {
gfn_t gfn;
u64 *spt;
- /* hold the gfn of each spte inside spt */
- gfn_t *gfns;
+
+ /*
+ * Stores the result of the guest translation being shadowed by each
+ * SPTE. KVM shadows two types of guest translations: nGPA -> GPA
+ * (shadow EPT/NPT) and GVA -> GPA (traditional shadow paging). In both
+ * cases the result of the translation is a GPA and a set of access
+ * constraints.
+ *
+ * The GFN is stored in the upper bits (PAGE_SHIFT) and the shadowed
+ * access permissions are stored in the lower bits. Note, for
+ * convenience and uniformity across guests, the access permissions are
+ * stored in KVM format (e.g. ACC_EXEC_MASK) not the raw guest format.
+ */
+ u64 *shadowed_translation;
+
/* Currently serving as active root */
union {
int root_count;
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index fd73c857af90..37ceb6e452e6 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -979,7 +979,8 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
}
/*
- * Using the cached information from sp->gfns is safe because:
+ * Using the information in sp->shadowed_translation (kvm_mmu_page_get_gfn()) is
+ * safe because:
* - The spte has a reference to the struct page, so the pfn for a given gfn
* can't change unless all sptes pointing to it are nuked first.
*
@@ -1054,12 +1055,15 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp)
if (sync_mmio_spte(vcpu, &sp->spt[i], gfn, pte_access))
continue;
- if (gfn != sp->gfns[i]) {
+ if (gfn != kvm_mmu_page_get_gfn(sp, i)) {
drop_spte(vcpu->kvm, &sp->spt[i]);
flush = true;
continue;
}
+ /* Update the shadowed access bits in case they changed. */
+ kvm_mmu_page_set_access(sp, i, pte_access);
+
sptep = &sp->spt[i];
spte = *sptep;
host_writable = spte & shadow_host_writable_mask;
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 17/21] KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Currently make_huge_page_split_spte() assumes execute permissions can be
granted to any 4K SPTE when splitting huge pages. This is true for the
TDP MMU but is not necessarily true for the shadow MMU, since KVM may be
shadowing a non-executable huge page.
To fix this, pass in the role of the child shadow page where the huge
page will be split and derive the execution permission from that. This
is correct because huge pages are always split with direct shadow page
and thus the shadow page role contains the correct access permissions.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/spte.c | 16 ++++++++--------
arch/x86/kvm/mmu/spte.h | 2 +-
arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
3 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index b5960bbde7f7..237e8dc12993 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -244,10 +244,10 @@ static u64 make_spte_executable(u64 spte)
* This is used during huge page splitting to build the SPTEs that make up the
* new page table.
*/
-u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index)
+u64 make_huge_page_split_spte(u64 huge_spte, union kvm_mmu_page_role role,
+ int index)
{
u64 child_spte;
- int child_level;
if (WARN_ON_ONCE(!is_shadow_present_pte(huge_spte)))
return 0;
@@ -256,23 +256,23 @@ u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index)
return 0;
child_spte = huge_spte;
- child_level = huge_level - 1;
/*
* The child_spte already has the base address of the huge page being
* split. So we just have to OR in the offset to the page at the next
* lower level for the given index.
*/
- child_spte |= (index * KVM_PAGES_PER_HPAGE(child_level)) << PAGE_SHIFT;
+ child_spte |= (index * KVM_PAGES_PER_HPAGE(role.level)) << PAGE_SHIFT;
- if (child_level == PG_LEVEL_4K) {
+ if (role.level == PG_LEVEL_4K) {
child_spte &= ~PT_PAGE_SIZE_MASK;
/*
- * When splitting to a 4K page, mark the page executable as the
- * NX hugepage mitigation no longer applies.
+ * When splitting to a 4K page where execution is allowed, mark
+ * the page executable as the NX hugepage mitigation no longer
+ * applies.
*/
- if (is_nx_huge_page_enabled())
+ if ((role.access & ACC_EXEC_MASK) && is_nx_huge_page_enabled())
child_spte = make_spte_executable(child_spte);
}
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 0127bb6e3c7d..3dada44cc066 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -425,7 +425,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn,
u64 old_spte, bool prefetch, bool can_unsync,
bool host_writable, u64 *new_spte);
-u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index);
+u64 make_huge_page_split_spte(u64 huge_spte, union kvm_mmu_page_role role, int index);
u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled);
u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access);
u64 mark_spte_for_access_track(u64 spte);
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 841feaa48be5..a5472ee56080 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1488,7 +1488,7 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter,
* not been linked in yet and thus is not reachable from any other CPU.
*/
for (i = 0; i < PT64_ENT_PER_PAGE; i++)
- sp->spt[i] = make_huge_page_split_spte(huge_spte, level, i);
+ sp->spt[i] = make_huge_page_split_spte(huge_spte, sp->role, i);
/*
* Replace the huge spte with a pointer to the populated lower level
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 17/21] KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Currently make_huge_page_split_spte() assumes execute permissions can be
granted to any 4K SPTE when splitting huge pages. This is true for the
TDP MMU but is not necessarily true for the shadow MMU, since KVM may be
shadowing a non-executable huge page.
To fix this, pass in the role of the child shadow page where the huge
page will be split and derive the execution permission from that. This
is correct because huge pages are always split with direct shadow page
and thus the shadow page role contains the correct access permissions.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/spte.c | 16 ++++++++--------
arch/x86/kvm/mmu/spte.h | 2 +-
arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
3 files changed, 10 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/mmu/spte.c b/arch/x86/kvm/mmu/spte.c
index b5960bbde7f7..237e8dc12993 100644
--- a/arch/x86/kvm/mmu/spte.c
+++ b/arch/x86/kvm/mmu/spte.c
@@ -244,10 +244,10 @@ static u64 make_spte_executable(u64 spte)
* This is used during huge page splitting to build the SPTEs that make up the
* new page table.
*/
-u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index)
+u64 make_huge_page_split_spte(u64 huge_spte, union kvm_mmu_page_role role,
+ int index)
{
u64 child_spte;
- int child_level;
if (WARN_ON_ONCE(!is_shadow_present_pte(huge_spte)))
return 0;
@@ -256,23 +256,23 @@ u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index)
return 0;
child_spte = huge_spte;
- child_level = huge_level - 1;
/*
* The child_spte already has the base address of the huge page being
* split. So we just have to OR in the offset to the page at the next
* lower level for the given index.
*/
- child_spte |= (index * KVM_PAGES_PER_HPAGE(child_level)) << PAGE_SHIFT;
+ child_spte |= (index * KVM_PAGES_PER_HPAGE(role.level)) << PAGE_SHIFT;
- if (child_level == PG_LEVEL_4K) {
+ if (role.level == PG_LEVEL_4K) {
child_spte &= ~PT_PAGE_SIZE_MASK;
/*
- * When splitting to a 4K page, mark the page executable as the
- * NX hugepage mitigation no longer applies.
+ * When splitting to a 4K page where execution is allowed, mark
+ * the page executable as the NX hugepage mitigation no longer
+ * applies.
*/
- if (is_nx_huge_page_enabled())
+ if ((role.access & ACC_EXEC_MASK) && is_nx_huge_page_enabled())
child_spte = make_spte_executable(child_spte);
}
diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h
index 0127bb6e3c7d..3dada44cc066 100644
--- a/arch/x86/kvm/mmu/spte.h
+++ b/arch/x86/kvm/mmu/spte.h
@@ -425,7 +425,7 @@ bool make_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
unsigned int pte_access, gfn_t gfn, kvm_pfn_t pfn,
u64 old_spte, bool prefetch, bool can_unsync,
bool host_writable, u64 *new_spte);
-u64 make_huge_page_split_spte(u64 huge_spte, int huge_level, int index);
+u64 make_huge_page_split_spte(u64 huge_spte, union kvm_mmu_page_role role, int index);
u64 make_nonleaf_spte(u64 *child_pt, bool ad_disabled);
u64 make_mmio_spte(struct kvm_vcpu *vcpu, u64 gfn, unsigned int access);
u64 mark_spte_for_access_track(u64 spte);
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 841feaa48be5..a5472ee56080 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1488,7 +1488,7 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter,
* not been linked in yet and thus is not reachable from any other CPU.
*/
for (i = 0; i < PT64_ENT_PER_PAGE; i++)
- sp->spt[i] = make_huge_page_split_spte(huge_spte, level, i);
+ sp->spt[i] = make_huge_page_split_spte(huge_spte, sp->role, i);
/*
* Replace the huge spte with a pointer to the populated lower level
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 18/21] KVM: x86/mmu: Zap collapsible SPTEs in shadow MMU at all possible levels
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Currently KVM only zaps collapsible 4KiB SPTEs in the shadow MMU. This
is fine for now since KVM never creates intermediate huge pages during
dirty logging. In other words, KVM always replaces 1GiB pages directly
with 4KiB pages, so there is no reason to look for collapsible 2MiB
pages.
However, this will stop being true once the shadow MMU participates in
eager page splitting. During eager page splitting, each 1GiB is first
split into 2MiB pages and then those are split into 4KiB pages. The
intermediate 2MiB pages may be left behind if an error condition causes
eager page splitting to bail early.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b411b0d202c8..ef190dd77ccc 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6183,18 +6183,25 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
return need_tlb_flush;
}
+static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm,
+ const struct kvm_memory_slot *slot)
+{
+ /*
+ * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap
+ * pages that are already mapped at the maximum possible level.
+ */
+ if (slot_handle_level(kvm, slot, kvm_mmu_zap_collapsible_spte,
+ PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1,
+ true))
+ kvm_arch_flush_remote_tlbs_memslot(kvm, slot);
+}
+
void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
const struct kvm_memory_slot *slot)
{
if (kvm_memslots_have_rmaps(kvm)) {
write_lock(&kvm->mmu_lock);
- /*
- * Zap only 4k SPTEs since the legacy MMU only supports dirty
- * logging at a 4k granularity and never creates collapsible
- * 2m SPTEs during dirty logging.
- */
- if (slot_handle_level_4k(kvm, slot, kvm_mmu_zap_collapsible_spte, true))
- kvm_arch_flush_remote_tlbs_memslot(kvm, slot);
+ kvm_rmap_zap_collapsible_sptes(kvm, slot);
write_unlock(&kvm->mmu_lock);
}
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 18/21] KVM: x86/mmu: Zap collapsible SPTEs in shadow MMU at all possible levels
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Currently KVM only zaps collapsible 4KiB SPTEs in the shadow MMU. This
is fine for now since KVM never creates intermediate huge pages during
dirty logging. In other words, KVM always replaces 1GiB pages directly
with 4KiB pages, so there is no reason to look for collapsible 2MiB
pages.
However, this will stop being true once the shadow MMU participates in
eager page splitting. During eager page splitting, each 1GiB is first
split into 2MiB pages and then those are split into 4KiB pages. The
intermediate 2MiB pages may be left behind if an error condition causes
eager page splitting to bail early.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index b411b0d202c8..ef190dd77ccc 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6183,18 +6183,25 @@ static bool kvm_mmu_zap_collapsible_spte(struct kvm *kvm,
return need_tlb_flush;
}
+static void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm,
+ const struct kvm_memory_slot *slot)
+{
+ /*
+ * Note, use KVM_MAX_HUGEPAGE_LEVEL - 1 since there's no need to zap
+ * pages that are already mapped at the maximum possible level.
+ */
+ if (slot_handle_level(kvm, slot, kvm_mmu_zap_collapsible_spte,
+ PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL - 1,
+ true))
+ kvm_arch_flush_remote_tlbs_memslot(kvm, slot);
+}
+
void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm,
const struct kvm_memory_slot *slot)
{
if (kvm_memslots_have_rmaps(kvm)) {
write_lock(&kvm->mmu_lock);
- /*
- * Zap only 4k SPTEs since the legacy MMU only supports dirty
- * logging at a 4k granularity and never creates collapsible
- * 2m SPTEs during dirty logging.
- */
- if (slot_handle_level_4k(kvm, slot, kvm_mmu_zap_collapsible_spte, true))
- kvm_arch_flush_remote_tlbs_memslot(kvm, slot);
+ kvm_rmap_zap_collapsible_sptes(kvm, slot);
write_unlock(&kvm->mmu_lock);
}
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 19/21] KVM: x86/mmu: Refactor drop_large_spte()
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
drop_large_spte() drops a large SPTE if it exists and then flushes TLBs.
Its helper function, __drop_large_spte(), does the drop without the
flush.
In preparation for eager page splitting, which will need to sometimes
flush when dropping large SPTEs (and sometimes not), push the flushing
logic down into __drop_large_spte() and add a bool parameter to control
it.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ef190dd77ccc..4b40fa2e27eb 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1161,26 +1161,26 @@ static void drop_spte(struct kvm *kvm, u64 *sptep)
rmap_remove(kvm, sptep);
}
-
-static bool __drop_large_spte(struct kvm *kvm, u64 *sptep)
+static void __drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush)
{
- if (is_large_pte(*sptep)) {
- WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K);
- drop_spte(kvm, sptep);
- return true;
- }
+ struct kvm_mmu_page *sp;
- return false;
+ if (!is_large_pte(*sptep))
+ return;
+
+ sp = sptep_to_sp(sptep);
+ WARN_ON(sp->role.level == PG_LEVEL_4K);
+
+ drop_spte(kvm, sptep);
+
+ if (flush)
+ kvm_flush_remote_tlbs_with_address(kvm, sp->gfn,
+ KVM_PAGES_PER_HPAGE(sp->role.level));
}
static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
{
- if (__drop_large_spte(vcpu->kvm, sptep)) {
- struct kvm_mmu_page *sp = sptep_to_sp(sptep);
-
- kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
- KVM_PAGES_PER_HPAGE(sp->role.level));
- }
+ return __drop_large_spte(vcpu->kvm, sptep, true);
}
/*
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 19/21] KVM: x86/mmu: Refactor drop_large_spte()
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
drop_large_spte() drops a large SPTE if it exists and then flushes TLBs.
Its helper function, __drop_large_spte(), does the drop without the
flush.
In preparation for eager page splitting, which will need to sometimes
flush when dropping large SPTEs (and sometimes not), push the flushing
logic down into __drop_large_spte() and add a bool parameter to control
it.
No functional change intended.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/mmu.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index ef190dd77ccc..4b40fa2e27eb 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1161,26 +1161,26 @@ static void drop_spte(struct kvm *kvm, u64 *sptep)
rmap_remove(kvm, sptep);
}
-
-static bool __drop_large_spte(struct kvm *kvm, u64 *sptep)
+static void __drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush)
{
- if (is_large_pte(*sptep)) {
- WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K);
- drop_spte(kvm, sptep);
- return true;
- }
+ struct kvm_mmu_page *sp;
- return false;
+ if (!is_large_pte(*sptep))
+ return;
+
+ sp = sptep_to_sp(sptep);
+ WARN_ON(sp->role.level == PG_LEVEL_4K);
+
+ drop_spte(kvm, sptep);
+
+ if (flush)
+ kvm_flush_remote_tlbs_with_address(kvm, sp->gfn,
+ KVM_PAGES_PER_HPAGE(sp->role.level));
}
static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
{
- if (__drop_large_spte(vcpu->kvm, sptep)) {
- struct kvm_mmu_page *sp = sptep_to_sp(sptep);
-
- kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
- KVM_PAGES_PER_HPAGE(sp->role.level));
- }
+ return __drop_large_spte(vcpu->kvm, sptep, true);
}
/*
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
declaration time rather than being fixed for all declarations. This will
be used in a follow-up commit to declare an cache in x86 with a capacity
of 512+ objects without having to increase the capacity of all caches in
KVM.
This change requires each cache now specify its capacity at runtime,
since the cache struct itself no longer has a fixed capacity known at
compile time. To protect against someone accidentally defining a
kvm_mmu_memory_cache struct directly (without the extra storage), this
commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
In order to support different capacities, this commit changes the
objects pointer array to be dynamically allocated the first time the
cache is topped-up.
An alternative would be to lay out the objects array after the
kvm_mmu_memory_cache struct, which can be done at compile time. But that
change, unfortunately, adds some grottiness to arm64 and riscv, which
uses a function-local (i.e. stack-allocated) kvm_mmu_memory_cache
struct. Since C does not allow anonymous structs in functions, the new
wrapper struct that contains kvm_mmu_memory_cache and the objects
pointer array, must be named, which means dealing with an outer and
inner struct. The outer struct can't be dropped since then there would
be no guarantee the kvm_mmu_memory_cache struct and objects array would
be laid out consecutively on the stack.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/mmu.c | 5 ++++-
arch/mips/kvm/mips.c | 2 ++
arch/riscv/kvm/mmu.c | 8 ++++----
arch/riscv/kvm/vcpu.c | 1 +
arch/x86/kvm/mmu/mmu.c | 9 +++++++++
include/linux/kvm_types.h | 9 +++++++--
virt/kvm/kvm_main.c | 20 ++++++++++++++++++--
8 files changed, 46 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 7fceb855fa71..aa1e0c1659d4 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -320,6 +320,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
vcpu->arch.target = -1;
bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
+ vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
/* Set up the timer */
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 53ae2c0640bc..2f2ef6b60ff4 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
{
phys_addr_t addr;
int ret = 0;
- struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
+ struct kvm_mmu_memory_cache cache = {
+ .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
+ .gfp_zero = __GFP_ZERO,
+ };
struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
KVM_PGTABLE_PROT_R |
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index a25e0b73ee70..45c7179144dc 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -387,6 +387,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
if (err)
goto out_free_gebase;
+ vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
+
return 0;
out_free_gebase:
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index f80a34fbf102..8c2338ecc246 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -347,10 +347,10 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
int ret = 0;
unsigned long pfn;
phys_addr_t addr, end;
- struct kvm_mmu_memory_cache pcache;
-
- memset(&pcache, 0, sizeof(pcache));
- pcache.gfp_zero = __GFP_ZERO;
+ struct kvm_mmu_memory_cache pcache = {
+ .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
+ .gfp_zero = __GFP_ZERO,
+ };
end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
pfn = __phys_to_pfn(hpa);
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 6785aef4cbd4..bbcb9d4a04fb 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -94,6 +94,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
/* Mark this VCPU never ran */
vcpu->arch.ran_atleast_once = false;
+ vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
/* Setup ISA features available to VCPU */
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4b40fa2e27eb..dad7e19ef8ed 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5803,12 +5803,21 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
{
int ret;
+ vcpu->arch.mmu_pte_list_desc_cache.capacity =
+ KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_page_header_cache.capacity =
+ KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_shadowed_info_cache.capacity =
+ KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
+
+ vcpu->arch.mmu_shadow_page_cache.capacity =
+ KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
vcpu->arch.mmu = &vcpu->arch.root_mmu;
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index ac1ebb37a0ff..549103a4f7bc 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -83,14 +83,19 @@ struct gfn_to_pfn_cache {
* MMU flows is problematic, as is triggering reclaim, I/O, etc... while
* holding MMU locks. Note, these caches act more like prefetch buffers than
* classical caches, i.e. objects are not returned to the cache on being freed.
+ *
+ * The storage for the cache object pointers is allocated dynamically when the
+ * cache is topped-up. The capacity field defines the number of object pointers
+ * available after the struct.
*/
struct kvm_mmu_memory_cache {
int nobjs;
+ int capacity;
gfp_t gfp_zero;
struct kmem_cache *kmem_cache;
- void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
+ void **objects;
};
-#endif
+#endif /* KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE */
#define HALT_POLL_HIST_COUNT 32
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e089db822c12..264e4107e06f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -371,12 +371,23 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
{
+ gfp_t gfp = GFP_KERNEL_ACCOUNT;
void *obj;
if (mc->nobjs >= min)
return 0;
- while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
- obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
+
+ if (WARN_ON(mc->capacity == 0))
+ return -EINVAL;
+
+ if (!mc->objects) {
+ mc->objects = kvmalloc_array(sizeof(void *), mc->capacity, gfp);
+ if (!mc->objects)
+ return -ENOMEM;
+ }
+
+ while (mc->nobjs < mc->capacity) {
+ obj = mmu_memory_cache_alloc_obj(mc, gfp);
if (!obj)
return mc->nobjs >= min ? 0 : -ENOMEM;
mc->objects[mc->nobjs++] = obj;
@@ -397,6 +408,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
else
free_page((unsigned long)mc->objects[--mc->nobjs]);
}
+
+ kvfree(mc->objects);
+
+ /* Note, must set to NULL to avoid use-after-free in the next top-up. */
+ mc->objects = NULL;
}
void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
declaration time rather than being fixed for all declarations. This will
be used in a follow-up commit to declare an cache in x86 with a capacity
of 512+ objects without having to increase the capacity of all caches in
KVM.
This change requires each cache now specify its capacity at runtime,
since the cache struct itself no longer has a fixed capacity known at
compile time. To protect against someone accidentally defining a
kvm_mmu_memory_cache struct directly (without the extra storage), this
commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
In order to support different capacities, this commit changes the
objects pointer array to be dynamically allocated the first time the
cache is topped-up.
An alternative would be to lay out the objects array after the
kvm_mmu_memory_cache struct, which can be done at compile time. But that
change, unfortunately, adds some grottiness to arm64 and riscv, which
uses a function-local (i.e. stack-allocated) kvm_mmu_memory_cache
struct. Since C does not allow anonymous structs in functions, the new
wrapper struct that contains kvm_mmu_memory_cache and the objects
pointer array, must be named, which means dealing with an outer and
inner struct. The outer struct can't be dropped since then there would
be no guarantee the kvm_mmu_memory_cache struct and objects array would
be laid out consecutively on the stack.
No functional change intended.
Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/mmu.c | 5 ++++-
arch/mips/kvm/mips.c | 2 ++
arch/riscv/kvm/mmu.c | 8 ++++----
arch/riscv/kvm/vcpu.c | 1 +
arch/x86/kvm/mmu/mmu.c | 9 +++++++++
include/linux/kvm_types.h | 9 +++++++--
virt/kvm/kvm_main.c | 20 ++++++++++++++++++--
8 files changed, 46 insertions(+), 9 deletions(-)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 7fceb855fa71..aa1e0c1659d4 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -320,6 +320,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
vcpu->arch.target = -1;
bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
+ vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
/* Set up the timer */
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 53ae2c0640bc..2f2ef6b60ff4 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
{
phys_addr_t addr;
int ret = 0;
- struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
+ struct kvm_mmu_memory_cache cache = {
+ .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
+ .gfp_zero = __GFP_ZERO,
+ };
struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
KVM_PGTABLE_PROT_R |
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index a25e0b73ee70..45c7179144dc 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -387,6 +387,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
if (err)
goto out_free_gebase;
+ vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
+
return 0;
out_free_gebase:
diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
index f80a34fbf102..8c2338ecc246 100644
--- a/arch/riscv/kvm/mmu.c
+++ b/arch/riscv/kvm/mmu.c
@@ -347,10 +347,10 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
int ret = 0;
unsigned long pfn;
phys_addr_t addr, end;
- struct kvm_mmu_memory_cache pcache;
-
- memset(&pcache, 0, sizeof(pcache));
- pcache.gfp_zero = __GFP_ZERO;
+ struct kvm_mmu_memory_cache pcache = {
+ .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
+ .gfp_zero = __GFP_ZERO,
+ };
end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
pfn = __phys_to_pfn(hpa);
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index 6785aef4cbd4..bbcb9d4a04fb 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -94,6 +94,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
/* Mark this VCPU never ran */
vcpu->arch.ran_atleast_once = false;
+ vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
/* Setup ISA features available to VCPU */
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 4b40fa2e27eb..dad7e19ef8ed 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5803,12 +5803,21 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
{
int ret;
+ vcpu->arch.mmu_pte_list_desc_cache.capacity =
+ KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_page_header_cache.capacity =
+ KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
+ vcpu->arch.mmu_shadowed_info_cache.capacity =
+ KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
+
+ vcpu->arch.mmu_shadow_page_cache.capacity =
+ KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
vcpu->arch.mmu = &vcpu->arch.root_mmu;
diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index ac1ebb37a0ff..549103a4f7bc 100644
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -83,14 +83,19 @@ struct gfn_to_pfn_cache {
* MMU flows is problematic, as is triggering reclaim, I/O, etc... while
* holding MMU locks. Note, these caches act more like prefetch buffers than
* classical caches, i.e. objects are not returned to the cache on being freed.
+ *
+ * The storage for the cache object pointers is allocated dynamically when the
+ * cache is topped-up. The capacity field defines the number of object pointers
+ * available after the struct.
*/
struct kvm_mmu_memory_cache {
int nobjs;
+ int capacity;
gfp_t gfp_zero;
struct kmem_cache *kmem_cache;
- void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
+ void **objects;
};
-#endif
+#endif /* KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE */
#define HALT_POLL_HIST_COUNT 32
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index e089db822c12..264e4107e06f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -371,12 +371,23 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
{
+ gfp_t gfp = GFP_KERNEL_ACCOUNT;
void *obj;
if (mc->nobjs >= min)
return 0;
- while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
- obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
+
+ if (WARN_ON(mc->capacity == 0))
+ return -EINVAL;
+
+ if (!mc->objects) {
+ mc->objects = kvmalloc_array(sizeof(void *), mc->capacity, gfp);
+ if (!mc->objects)
+ return -ENOMEM;
+ }
+
+ while (mc->nobjs < mc->capacity) {
+ obj = mmu_memory_cache_alloc_obj(mc, gfp);
if (!obj)
return mc->nobjs >= min ? 0 : -ENOMEM;
mc->objects[mc->nobjs++] = obj;
@@ -397,6 +408,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
else
free_page((unsigned long)mc->objects[--mc->nobjs]);
}
+
+ kvfree(mc->objects);
+
+ /* Note, must set to NULL to avoid use-after-free in the next top-up. */
+ mc->objects = NULL;
}
void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
--
2.36.0.550.gb090851708-goog
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 21/21] KVM: x86/mmu: Extend Eager Page Splitting to nested MMUs
2022-05-13 20:27 ` David Matlack
@ 2022-05-13 20:28 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Marc Zyngier, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan, David Matlack
Add support for Eager Page Splitting pages that are mapped by nested
MMUs. Walk through the rmap first splitting all 1GiB pages to 2MiB
pages, and then splitting all 2MiB pages to 4KiB pages.
Note, Eager Page Splitting is limited to nested MMUs as a policy rather
than due to any technical reason (the sp->role.guest_mode check could
just be deleted and Eager Page Splitting would work correctly for all
shadow MMU pages). There is really no reason to support Eager Page
Splitting for tdp_mmu=N, since such support will eventually be phased
out, and there is no current use case supporting Eager Page Splitting on
hosts where TDP is either disabled or unavailable in hardware.
Furthermore, future improvements to nested MMU scalability may diverge
the code from the legacy shadow paging implementation. These
improvements will be simpler to make if Eager Page Splitting does not
have to worry about legacy shadow paging.
Splitting huge pages mapped by nested MMUs requires dealing with some
extra complexity beyond that of the TDP MMU:
(1) The shadow MMU has a limit on the number of shadow pages that are
allowed to be allocated. So, as a policy, Eager Page Splitting
refuses to split if there are KVM_MIN_FREE_MMU_PAGES or fewer
pages available.
(2) Splitting a huge page may end up re-using an existing lower level
shadow page tables. This is unlike the TDP MMU which always allocates
new shadow page tables when splitting.
(3) When installing the lower level SPTEs, they must be added to the
rmap which may require allocating additional pte_list_desc structs.
Case (2) is especially interesting since it may require a TLB flush,
unlike the TDP MMU which can fully split huge pages without any TLB
flushes. Specifically, an existing lower level page table may point to
even lower level page tables that are not fully populated, effectively
unmapping a portion of the huge page, which requires a flush.
This commit performs such flushes after dropping the huge page and
before installing the lower level page table. This TLB flush could
instead be delayed until the MMU lock is about to be dropped, which
would batch flushes for multiple splits. However these flushes should
be rare in practice (a huge page must be aliased in multiple SPTEs and
have been split for NX Huge Pages in only some of them). Flushing
immediately is simpler to plumb and also reduces the chances of tripping
over a CPU bug (e.g. see iTLB multihit).
Suggested-by: Peter Feiner <pfeiner@google.com>
[ This commit is based off of the original implementation of Eager Page
Splitting from Peter in Google's kernel from 2016. ]
Signed-off-by: David Matlack <dmatlack@google.com>
---
.../admin-guide/kernel-parameters.txt | 3 +-
arch/x86/include/asm/kvm_host.h | 24 ++
arch/x86/kvm/mmu/mmu.c | 269 +++++++++++++++++-
arch/x86/kvm/x86.c | 6 +
4 files changed, 293 insertions(+), 9 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3f1cc5e317ed..bc3ad3d4df0b 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2387,8 +2387,7 @@
the KVM_CLEAR_DIRTY ioctl, and only for the pages being
cleared.
- Eager page splitting currently only supports splitting
- huge pages mapped by the TDP MMU.
+ Eager page splitting is only supported when kvm.tdp_mmu=Y.
Default is Y (on).
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9193a700fe2d..ea99e61cc556 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1265,6 +1265,28 @@ struct kvm_arch {
* the global KVM_MAX_VCPU_IDS may lead to significant memory waste.
*/
u32 max_vcpu_ids;
+
+ /*
+ * Memory caches used to allocate shadow pages when performing eager
+ * page splitting. No need for a shadowed_info_cache since eager page
+ * splitting only allocates direct shadow pages.
+ *
+ * Protected by kvm->slots_lock.
+ */
+ struct kvm_mmu_memory_cache split_shadow_page_cache;
+ struct kvm_mmu_memory_cache split_page_header_cache;
+
+ /*
+ * Memory cache used to allocate pte_list_desc structs while splitting
+ * huge pages. In the worst case, to split one huge page, 512
+ * pte_list_desc structs are needed to add each lower level leaf sptep
+ * to the rmap plus 1 to extend the parent_ptes rmap of the lower level
+ * page table.
+ *
+ * Protected by kvm->slots_lock.
+ */
+#define SPLIT_DESC_CACHE_CAPACITY 513
+ struct kvm_mmu_memory_cache split_desc_cache;
};
struct kvm_vm_stat {
@@ -1639,6 +1661,8 @@ void kvm_mmu_zap_all(struct kvm *kvm);
void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen);
void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long kvm_nr_mmu_pages);
+void free_split_caches(struct kvm *kvm);
+
int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3);
int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index dad7e19ef8ed..3d3ec5e66195 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5981,6 +5981,18 @@ int kvm_mmu_init_vm(struct kvm *kvm)
node->track_write = kvm_mmu_pte_write;
node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
kvm_page_track_register_notifier(kvm, node);
+
+ kvm->arch.split_page_header_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
+ kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache;
+ kvm->arch.split_page_header_cache.gfp_zero = __GFP_ZERO;
+
+ kvm->arch.split_shadow_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
+ kvm->arch.split_shadow_page_cache.gfp_zero = __GFP_ZERO;
+
+ kvm->arch.split_desc_cache.capacity = SPLIT_DESC_CACHE_CAPACITY;
+ kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache;
+ kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO;
+
return 0;
}
@@ -6112,15 +6124,251 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
}
+void free_split_caches(struct kvm *kvm)
+{
+ lockdep_assert_held(&kvm->slots_lock);
+
+ kvm_mmu_free_memory_cache(&kvm->arch.split_desc_cache);
+ kvm_mmu_free_memory_cache(&kvm->arch.split_page_header_cache);
+ kvm_mmu_free_memory_cache(&kvm->arch.split_shadow_page_cache);
+}
+
+static inline bool need_topup(struct kvm_mmu_memory_cache *cache, int min)
+{
+ return kvm_mmu_memory_cache_nr_free_objects(cache) < min;
+}
+
+static bool need_topup_split_caches_or_resched(struct kvm *kvm)
+{
+ if (need_resched() || rwlock_needbreak(&kvm->mmu_lock))
+ return true;
+
+ /*
+ * In the worst case, SPLIT_DESC_CACHE_CAPACITY descriptors are needed
+ * to split a single huge page. Calculating how many are actually needed
+ * is possible but not worth the complexity.
+ */
+ return need_topup(&kvm->arch.split_desc_cache, SPLIT_DESC_CACHE_CAPACITY) ||
+ need_topup(&kvm->arch.split_page_header_cache, 1) ||
+ need_topup(&kvm->arch.split_shadow_page_cache, 1);
+}
+
+static int topup_split_caches(struct kvm *kvm)
+{
+ int r;
+
+ lockdep_assert_held(&kvm->slots_lock);
+
+ r = kvm_mmu_topup_memory_cache(&kvm->arch.split_desc_cache,
+ SPLIT_DESC_CACHE_CAPACITY);
+ if (r)
+ return r;
+
+ r = kvm_mmu_topup_memory_cache(&kvm->arch.split_page_header_cache, 1);
+ if (r)
+ return r;
+
+ return kvm_mmu_topup_memory_cache(&kvm->arch.split_shadow_page_cache, 1);
+}
+
+static struct kvm_mmu_page *nested_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep)
+{
+ struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep);
+ struct shadow_page_caches caches = {};
+ union kvm_mmu_page_role role;
+ unsigned int access;
+ gfn_t gfn;
+
+ gfn = kvm_mmu_page_get_gfn(huge_sp, huge_sptep - huge_sp->spt);
+ access = kvm_mmu_page_get_access(huge_sp, huge_sptep - huge_sp->spt);
+
+ /*
+ * Note, huge page splitting always uses direct shadow pages, regardless
+ * of whether the huge page itself is mapped by a direct or indirect
+ * shadow page, since the huge page region itself is being directly
+ * mapped with smaller pages.
+ */
+ role = kvm_mmu_child_role(huge_sptep, /*direct=*/true, access);
+
+ /* Direct SPs do not require a shadowed_info_cache. */
+ caches.page_header_cache = &kvm->arch.split_page_header_cache;
+ caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache;
+
+ /* Safe to pass NULL for vCPU since requesting a direct SP. */
+ return __kvm_mmu_get_shadow_page(kvm, NULL, &caches, gfn, role);
+}
+
+static void nested_mmu_split_huge_page(struct kvm *kvm,
+ const struct kvm_memory_slot *slot,
+ u64 *huge_sptep)
+
+{
+ struct kvm_mmu_memory_cache *cache = &kvm->arch.split_desc_cache;
+ u64 huge_spte = READ_ONCE(*huge_sptep);
+ struct kvm_mmu_page *sp;
+ bool flush = false;
+ u64 *sptep, spte;
+ gfn_t gfn;
+ int index;
+
+ sp = nested_mmu_get_sp_for_split(kvm, huge_sptep);
+
+ for (index = 0; index < PT64_ENT_PER_PAGE; index++) {
+ sptep = &sp->spt[index];
+ gfn = kvm_mmu_page_get_gfn(sp, index);
+
+ /*
+ * The SP may already have populated SPTEs, e.g. if this huge
+ * page is aliased by multiple sptes with the same access
+ * permissions. These entries are guaranteed to map the same
+ * gfn-to-pfn translation since the SP is direct, so no need to
+ * modify them.
+ *
+ * However, if a given SPTE points to a lower level page table,
+ * that lower level page table may only be partially populated.
+ * Installing such SPTEs would effectively unmap a potion of the
+ * huge page. Unmapping guest memory always requires a TLB flush
+ * since a subsequent operation on the unmapped regions would
+ * fail to detect the need to flush.
+ */
+ if (is_shadow_present_pte(*sptep)) {
+ flush |= !is_last_spte(*sptep, sp->role.level);
+ continue;
+ }
+
+ spte = make_huge_page_split_spte(huge_spte, sp->role, index);
+ mmu_spte_set(sptep, spte);
+ __rmap_add(kvm, cache, slot, sptep, gfn, sp->role.access);
+ }
+
+ /*
+ * Replace the huge spte with a pointer to the populated lower level
+ * page table. If the lower-level page table indentically maps the huge
+ * page (i.e. no memory is unmapped), there's no need for a TLB flush.
+ * Otherwise, flush TLBs after dropping the huge page and before
+ * installing the shadow page table.
+ */
+ __drop_large_spte(kvm, huge_sptep, flush);
+ __link_shadow_page(cache, huge_sptep, sp);
+}
+
+static int nested_mmu_try_split_huge_page(struct kvm *kvm,
+ const struct kvm_memory_slot *slot,
+ u64 *huge_sptep)
+{
+ struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep);
+ int level, r = 0;
+ gfn_t gfn;
+ u64 spte;
+
+ /* Grab information for the tracepoint before dropping the MMU lock. */
+ gfn = kvm_mmu_page_get_gfn(huge_sp, huge_sptep - huge_sp->spt);
+ level = huge_sp->role.level;
+ spte = *huge_sptep;
+
+ if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) {
+ r = -ENOSPC;
+ goto out;
+ }
+
+ if (need_topup_split_caches_or_resched(kvm)) {
+ write_unlock(&kvm->mmu_lock);
+ cond_resched();
+ /*
+ * If the topup succeeds, return -EAGAIN to indicate that the
+ * rmap iterator should be restarted because the MMU lock was
+ * dropped.
+ */
+ r = topup_split_caches(kvm) ?: -EAGAIN;
+ write_lock(&kvm->mmu_lock);
+ goto out;
+ }
+
+ nested_mmu_split_huge_page(kvm, slot, huge_sptep);
+
+out:
+ trace_kvm_mmu_split_huge_page(gfn, spte, level, r);
+ return r;
+}
+
+static bool nested_mmu_try_split_huge_pages(struct kvm *kvm,
+ struct kvm_rmap_head *rmap_head,
+ const struct kvm_memory_slot *slot)
+{
+ struct rmap_iterator iter;
+ struct kvm_mmu_page *sp;
+ u64 *huge_sptep;
+ int r;
+
+restart:
+ for_each_rmap_spte(rmap_head, &iter, huge_sptep) {
+ sp = sptep_to_sp(huge_sptep);
+
+ /* TDP MMU is enabled, so rmap only contains nested MMU SPs. */
+ if (WARN_ON_ONCE(!sp->role.guest_mode))
+ continue;
+
+ /* The rmaps should never contain non-leaf SPTEs. */
+ if (WARN_ON_ONCE(!is_large_pte(*huge_sptep)))
+ continue;
+
+ /* SPs with level >PG_LEVEL_4K should never by unsync. */
+ if (WARN_ON_ONCE(sp->unsync))
+ continue;
+
+ /* Don't bother splitting huge pages on invalid SPs. */
+ if (sp->role.invalid)
+ continue;
+
+ r = nested_mmu_try_split_huge_page(kvm, slot, huge_sptep);
+
+ /*
+ * The split succeeded or needs to be retried because the MMU
+ * lock was dropped. Either way, restart the iterator to get it
+ * back into a consistent state.
+ */
+ if (!r || r == -EAGAIN)
+ goto restart;
+
+ /* The split failed and shouldn't be retried (e.g. -ENOMEM). */
+ break;
+ }
+
+ return false;
+}
+
+static void kvm_nested_mmu_try_split_huge_pages(struct kvm *kvm,
+ const struct kvm_memory_slot *slot,
+ gfn_t start, gfn_t end,
+ int target_level)
+{
+ int level;
+
+ /*
+ * Split huge pages starting with KVM_MAX_HUGEPAGE_LEVEL and working
+ * down to the target level. This ensures pages are recursively split
+ * all the way to the target level. There's no need to split pages
+ * already at the target level.
+ */
+ for (level = KVM_MAX_HUGEPAGE_LEVEL; level > target_level; level--) {
+ slot_handle_level_range(kvm, slot, nested_mmu_try_split_huge_pages,
+ level, level, start, end - 1, true, false);
+ }
+}
+
/* Must be called with the mmu_lock held in write-mode. */
void kvm_mmu_try_split_huge_pages(struct kvm *kvm,
const struct kvm_memory_slot *memslot,
u64 start, u64 end,
int target_level)
{
- if (is_tdp_mmu_enabled(kvm))
- kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end,
- target_level, false);
+ if (!is_tdp_mmu_enabled(kvm))
+ return;
+
+ if (kvm_memslots_have_rmaps(kvm))
+ kvm_nested_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level);
+
+ kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, false);
/*
* A TLB flush is unnecessary at this point for the same resons as in
@@ -6135,12 +6383,19 @@ void kvm_mmu_slot_try_split_huge_pages(struct kvm *kvm,
u64 start = memslot->base_gfn;
u64 end = start + memslot->npages;
- if (is_tdp_mmu_enabled(kvm)) {
- read_lock(&kvm->mmu_lock);
- kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, true);
- read_unlock(&kvm->mmu_lock);
+ if (!is_tdp_mmu_enabled(kvm))
+ return;
+
+ if (kvm_memslots_have_rmaps(kvm)) {
+ write_lock(&kvm->mmu_lock);
+ kvm_nested_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level);
+ write_unlock(&kvm->mmu_lock);
}
+ read_lock(&kvm->mmu_lock);
+ kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, true);
+ read_unlock(&kvm->mmu_lock);
+
/*
* No TLB flush is necessary here. KVM will flush TLBs after
* write-protecting and/or clearing dirty on the newly split SPTEs to
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 04812eaaf61b..4fe018ddd1cd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12197,6 +12197,12 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
* page faults will create the large-page sptes.
*/
kvm_mmu_zap_collapsible_sptes(kvm, new);
+
+ /*
+ * Free any memory left behind by eager page splitting. Ignore
+ * the module parameter since userspace might have changed it.
+ */
+ free_split_caches(kvm);
} else {
/*
* Initially-all-set does not require write protecting any page,
--
2.36.0.550.gb090851708-goog
^ permalink raw reply related [flat|nested] 60+ messages in thread
* [PATCH v5 21/21] KVM: x86/mmu: Extend Eager Page Splitting to nested MMUs
@ 2022-05-13 20:28 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-13 20:28 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
David Matlack, Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
Add support for Eager Page Splitting pages that are mapped by nested
MMUs. Walk through the rmap first splitting all 1GiB pages to 2MiB
pages, and then splitting all 2MiB pages to 4KiB pages.
Note, Eager Page Splitting is limited to nested MMUs as a policy rather
than due to any technical reason (the sp->role.guest_mode check could
just be deleted and Eager Page Splitting would work correctly for all
shadow MMU pages). There is really no reason to support Eager Page
Splitting for tdp_mmu=N, since such support will eventually be phased
out, and there is no current use case supporting Eager Page Splitting on
hosts where TDP is either disabled or unavailable in hardware.
Furthermore, future improvements to nested MMU scalability may diverge
the code from the legacy shadow paging implementation. These
improvements will be simpler to make if Eager Page Splitting does not
have to worry about legacy shadow paging.
Splitting huge pages mapped by nested MMUs requires dealing with some
extra complexity beyond that of the TDP MMU:
(1) The shadow MMU has a limit on the number of shadow pages that are
allowed to be allocated. So, as a policy, Eager Page Splitting
refuses to split if there are KVM_MIN_FREE_MMU_PAGES or fewer
pages available.
(2) Splitting a huge page may end up re-using an existing lower level
shadow page tables. This is unlike the TDP MMU which always allocates
new shadow page tables when splitting.
(3) When installing the lower level SPTEs, they must be added to the
rmap which may require allocating additional pte_list_desc structs.
Case (2) is especially interesting since it may require a TLB flush,
unlike the TDP MMU which can fully split huge pages without any TLB
flushes. Specifically, an existing lower level page table may point to
even lower level page tables that are not fully populated, effectively
unmapping a portion of the huge page, which requires a flush.
This commit performs such flushes after dropping the huge page and
before installing the lower level page table. This TLB flush could
instead be delayed until the MMU lock is about to be dropped, which
would batch flushes for multiple splits. However these flushes should
be rare in practice (a huge page must be aliased in multiple SPTEs and
have been split for NX Huge Pages in only some of them). Flushing
immediately is simpler to plumb and also reduces the chances of tripping
over a CPU bug (e.g. see iTLB multihit).
Suggested-by: Peter Feiner <pfeiner@google.com>
[ This commit is based off of the original implementation of Eager Page
Splitting from Peter in Google's kernel from 2016. ]
Signed-off-by: David Matlack <dmatlack@google.com>
---
.../admin-guide/kernel-parameters.txt | 3 +-
arch/x86/include/asm/kvm_host.h | 24 ++
arch/x86/kvm/mmu/mmu.c | 269 +++++++++++++++++-
arch/x86/kvm/x86.c | 6 +
4 files changed, 293 insertions(+), 9 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3f1cc5e317ed..bc3ad3d4df0b 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2387,8 +2387,7 @@
the KVM_CLEAR_DIRTY ioctl, and only for the pages being
cleared.
- Eager page splitting currently only supports splitting
- huge pages mapped by the TDP MMU.
+ Eager page splitting is only supported when kvm.tdp_mmu=Y.
Default is Y (on).
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9193a700fe2d..ea99e61cc556 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1265,6 +1265,28 @@ struct kvm_arch {
* the global KVM_MAX_VCPU_IDS may lead to significant memory waste.
*/
u32 max_vcpu_ids;
+
+ /*
+ * Memory caches used to allocate shadow pages when performing eager
+ * page splitting. No need for a shadowed_info_cache since eager page
+ * splitting only allocates direct shadow pages.
+ *
+ * Protected by kvm->slots_lock.
+ */
+ struct kvm_mmu_memory_cache split_shadow_page_cache;
+ struct kvm_mmu_memory_cache split_page_header_cache;
+
+ /*
+ * Memory cache used to allocate pte_list_desc structs while splitting
+ * huge pages. In the worst case, to split one huge page, 512
+ * pte_list_desc structs are needed to add each lower level leaf sptep
+ * to the rmap plus 1 to extend the parent_ptes rmap of the lower level
+ * page table.
+ *
+ * Protected by kvm->slots_lock.
+ */
+#define SPLIT_DESC_CACHE_CAPACITY 513
+ struct kvm_mmu_memory_cache split_desc_cache;
};
struct kvm_vm_stat {
@@ -1639,6 +1661,8 @@ void kvm_mmu_zap_all(struct kvm *kvm);
void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen);
void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned long kvm_nr_mmu_pages);
+void free_split_caches(struct kvm *kvm);
+
int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3);
int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index dad7e19ef8ed..3d3ec5e66195 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5981,6 +5981,18 @@ int kvm_mmu_init_vm(struct kvm *kvm)
node->track_write = kvm_mmu_pte_write;
node->track_flush_slot = kvm_mmu_invalidate_zap_pages_in_memslot;
kvm_page_track_register_notifier(kvm, node);
+
+ kvm->arch.split_page_header_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
+ kvm->arch.split_page_header_cache.kmem_cache = mmu_page_header_cache;
+ kvm->arch.split_page_header_cache.gfp_zero = __GFP_ZERO;
+
+ kvm->arch.split_shadow_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
+ kvm->arch.split_shadow_page_cache.gfp_zero = __GFP_ZERO;
+
+ kvm->arch.split_desc_cache.capacity = SPLIT_DESC_CACHE_CAPACITY;
+ kvm->arch.split_desc_cache.kmem_cache = pte_list_desc_cache;
+ kvm->arch.split_desc_cache.gfp_zero = __GFP_ZERO;
+
return 0;
}
@@ -6112,15 +6124,251 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm,
kvm_arch_flush_remote_tlbs_memslot(kvm, memslot);
}
+void free_split_caches(struct kvm *kvm)
+{
+ lockdep_assert_held(&kvm->slots_lock);
+
+ kvm_mmu_free_memory_cache(&kvm->arch.split_desc_cache);
+ kvm_mmu_free_memory_cache(&kvm->arch.split_page_header_cache);
+ kvm_mmu_free_memory_cache(&kvm->arch.split_shadow_page_cache);
+}
+
+static inline bool need_topup(struct kvm_mmu_memory_cache *cache, int min)
+{
+ return kvm_mmu_memory_cache_nr_free_objects(cache) < min;
+}
+
+static bool need_topup_split_caches_or_resched(struct kvm *kvm)
+{
+ if (need_resched() || rwlock_needbreak(&kvm->mmu_lock))
+ return true;
+
+ /*
+ * In the worst case, SPLIT_DESC_CACHE_CAPACITY descriptors are needed
+ * to split a single huge page. Calculating how many are actually needed
+ * is possible but not worth the complexity.
+ */
+ return need_topup(&kvm->arch.split_desc_cache, SPLIT_DESC_CACHE_CAPACITY) ||
+ need_topup(&kvm->arch.split_page_header_cache, 1) ||
+ need_topup(&kvm->arch.split_shadow_page_cache, 1);
+}
+
+static int topup_split_caches(struct kvm *kvm)
+{
+ int r;
+
+ lockdep_assert_held(&kvm->slots_lock);
+
+ r = kvm_mmu_topup_memory_cache(&kvm->arch.split_desc_cache,
+ SPLIT_DESC_CACHE_CAPACITY);
+ if (r)
+ return r;
+
+ r = kvm_mmu_topup_memory_cache(&kvm->arch.split_page_header_cache, 1);
+ if (r)
+ return r;
+
+ return kvm_mmu_topup_memory_cache(&kvm->arch.split_shadow_page_cache, 1);
+}
+
+static struct kvm_mmu_page *nested_mmu_get_sp_for_split(struct kvm *kvm, u64 *huge_sptep)
+{
+ struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep);
+ struct shadow_page_caches caches = {};
+ union kvm_mmu_page_role role;
+ unsigned int access;
+ gfn_t gfn;
+
+ gfn = kvm_mmu_page_get_gfn(huge_sp, huge_sptep - huge_sp->spt);
+ access = kvm_mmu_page_get_access(huge_sp, huge_sptep - huge_sp->spt);
+
+ /*
+ * Note, huge page splitting always uses direct shadow pages, regardless
+ * of whether the huge page itself is mapped by a direct or indirect
+ * shadow page, since the huge page region itself is being directly
+ * mapped with smaller pages.
+ */
+ role = kvm_mmu_child_role(huge_sptep, /*direct=*/true, access);
+
+ /* Direct SPs do not require a shadowed_info_cache. */
+ caches.page_header_cache = &kvm->arch.split_page_header_cache;
+ caches.shadow_page_cache = &kvm->arch.split_shadow_page_cache;
+
+ /* Safe to pass NULL for vCPU since requesting a direct SP. */
+ return __kvm_mmu_get_shadow_page(kvm, NULL, &caches, gfn, role);
+}
+
+static void nested_mmu_split_huge_page(struct kvm *kvm,
+ const struct kvm_memory_slot *slot,
+ u64 *huge_sptep)
+
+{
+ struct kvm_mmu_memory_cache *cache = &kvm->arch.split_desc_cache;
+ u64 huge_spte = READ_ONCE(*huge_sptep);
+ struct kvm_mmu_page *sp;
+ bool flush = false;
+ u64 *sptep, spte;
+ gfn_t gfn;
+ int index;
+
+ sp = nested_mmu_get_sp_for_split(kvm, huge_sptep);
+
+ for (index = 0; index < PT64_ENT_PER_PAGE; index++) {
+ sptep = &sp->spt[index];
+ gfn = kvm_mmu_page_get_gfn(sp, index);
+
+ /*
+ * The SP may already have populated SPTEs, e.g. if this huge
+ * page is aliased by multiple sptes with the same access
+ * permissions. These entries are guaranteed to map the same
+ * gfn-to-pfn translation since the SP is direct, so no need to
+ * modify them.
+ *
+ * However, if a given SPTE points to a lower level page table,
+ * that lower level page table may only be partially populated.
+ * Installing such SPTEs would effectively unmap a potion of the
+ * huge page. Unmapping guest memory always requires a TLB flush
+ * since a subsequent operation on the unmapped regions would
+ * fail to detect the need to flush.
+ */
+ if (is_shadow_present_pte(*sptep)) {
+ flush |= !is_last_spte(*sptep, sp->role.level);
+ continue;
+ }
+
+ spte = make_huge_page_split_spte(huge_spte, sp->role, index);
+ mmu_spte_set(sptep, spte);
+ __rmap_add(kvm, cache, slot, sptep, gfn, sp->role.access);
+ }
+
+ /*
+ * Replace the huge spte with a pointer to the populated lower level
+ * page table. If the lower-level page table indentically maps the huge
+ * page (i.e. no memory is unmapped), there's no need for a TLB flush.
+ * Otherwise, flush TLBs after dropping the huge page and before
+ * installing the shadow page table.
+ */
+ __drop_large_spte(kvm, huge_sptep, flush);
+ __link_shadow_page(cache, huge_sptep, sp);
+}
+
+static int nested_mmu_try_split_huge_page(struct kvm *kvm,
+ const struct kvm_memory_slot *slot,
+ u64 *huge_sptep)
+{
+ struct kvm_mmu_page *huge_sp = sptep_to_sp(huge_sptep);
+ int level, r = 0;
+ gfn_t gfn;
+ u64 spte;
+
+ /* Grab information for the tracepoint before dropping the MMU lock. */
+ gfn = kvm_mmu_page_get_gfn(huge_sp, huge_sptep - huge_sp->spt);
+ level = huge_sp->role.level;
+ spte = *huge_sptep;
+
+ if (kvm_mmu_available_pages(kvm) <= KVM_MIN_FREE_MMU_PAGES) {
+ r = -ENOSPC;
+ goto out;
+ }
+
+ if (need_topup_split_caches_or_resched(kvm)) {
+ write_unlock(&kvm->mmu_lock);
+ cond_resched();
+ /*
+ * If the topup succeeds, return -EAGAIN to indicate that the
+ * rmap iterator should be restarted because the MMU lock was
+ * dropped.
+ */
+ r = topup_split_caches(kvm) ?: -EAGAIN;
+ write_lock(&kvm->mmu_lock);
+ goto out;
+ }
+
+ nested_mmu_split_huge_page(kvm, slot, huge_sptep);
+
+out:
+ trace_kvm_mmu_split_huge_page(gfn, spte, level, r);
+ return r;
+}
+
+static bool nested_mmu_try_split_huge_pages(struct kvm *kvm,
+ struct kvm_rmap_head *rmap_head,
+ const struct kvm_memory_slot *slot)
+{
+ struct rmap_iterator iter;
+ struct kvm_mmu_page *sp;
+ u64 *huge_sptep;
+ int r;
+
+restart:
+ for_each_rmap_spte(rmap_head, &iter, huge_sptep) {
+ sp = sptep_to_sp(huge_sptep);
+
+ /* TDP MMU is enabled, so rmap only contains nested MMU SPs. */
+ if (WARN_ON_ONCE(!sp->role.guest_mode))
+ continue;
+
+ /* The rmaps should never contain non-leaf SPTEs. */
+ if (WARN_ON_ONCE(!is_large_pte(*huge_sptep)))
+ continue;
+
+ /* SPs with level >PG_LEVEL_4K should never by unsync. */
+ if (WARN_ON_ONCE(sp->unsync))
+ continue;
+
+ /* Don't bother splitting huge pages on invalid SPs. */
+ if (sp->role.invalid)
+ continue;
+
+ r = nested_mmu_try_split_huge_page(kvm, slot, huge_sptep);
+
+ /*
+ * The split succeeded or needs to be retried because the MMU
+ * lock was dropped. Either way, restart the iterator to get it
+ * back into a consistent state.
+ */
+ if (!r || r == -EAGAIN)
+ goto restart;
+
+ /* The split failed and shouldn't be retried (e.g. -ENOMEM). */
+ break;
+ }
+
+ return false;
+}
+
+static void kvm_nested_mmu_try_split_huge_pages(struct kvm *kvm,
+ const struct kvm_memory_slot *slot,
+ gfn_t start, gfn_t end,
+ int target_level)
+{
+ int level;
+
+ /*
+ * Split huge pages starting with KVM_MAX_HUGEPAGE_LEVEL and working
+ * down to the target level. This ensures pages are recursively split
+ * all the way to the target level. There's no need to split pages
+ * already at the target level.
+ */
+ for (level = KVM_MAX_HUGEPAGE_LEVEL; level > target_level; level--) {
+ slot_handle_level_range(kvm, slot, nested_mmu_try_split_huge_pages,
+ level, level, start, end - 1, true, false);
+ }
+}
+
/* Must be called with the mmu_lock held in write-mode. */
void kvm_mmu_try_split_huge_pages(struct kvm *kvm,
const struct kvm_memory_slot *memslot,
u64 start, u64 end,
int target_level)
{
- if (is_tdp_mmu_enabled(kvm))
- kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end,
- target_level, false);
+ if (!is_tdp_mmu_enabled(kvm))
+ return;
+
+ if (kvm_memslots_have_rmaps(kvm))
+ kvm_nested_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level);
+
+ kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, false);
/*
* A TLB flush is unnecessary at this point for the same resons as in
@@ -6135,12 +6383,19 @@ void kvm_mmu_slot_try_split_huge_pages(struct kvm *kvm,
u64 start = memslot->base_gfn;
u64 end = start + memslot->npages;
- if (is_tdp_mmu_enabled(kvm)) {
- read_lock(&kvm->mmu_lock);
- kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, true);
- read_unlock(&kvm->mmu_lock);
+ if (!is_tdp_mmu_enabled(kvm))
+ return;
+
+ if (kvm_memslots_have_rmaps(kvm)) {
+ write_lock(&kvm->mmu_lock);
+ kvm_nested_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level);
+ write_unlock(&kvm->mmu_lock);
}
+ read_lock(&kvm->mmu_lock);
+ kvm_tdp_mmu_try_split_huge_pages(kvm, memslot, start, end, target_level, true);
+ read_unlock(&kvm->mmu_lock);
+
/*
* No TLB flush is necessary here. KVM will flush TLBs after
* write-protecting and/or clearing dirty on the newly split SPTEs to
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 04812eaaf61b..4fe018ddd1cd 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -12197,6 +12197,12 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
* page faults will create the large-page sptes.
*/
kvm_mmu_zap_collapsible_sptes(kvm, new);
+
+ /*
+ * Free any memory left behind by eager page splitting. Ignore
+ * the module parameter since userspace might have changed it.
+ */
+ free_split_caches(kvm);
} else {
/*
* Initially-all-set does not require write protecting any page,
--
2.36.0.550.gb090851708-goog
_______________________________________________
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^ permalink raw reply related [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
2022-05-13 20:28 ` David Matlack
@ 2022-05-15 11:42 ` Marc Zyngier
-1 siblings, 0 replies; 60+ messages in thread
From: Marc Zyngier @ 2022-05-15 11:42 UTC (permalink / raw)
To: David Matlack
Cc: Paolo Bonzini, Huacai Chen, Aleksandar Markovic, Anup Patel,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan
On Fri, 13 May 2022 21:28:18 +0100,
David Matlack <dmatlack@google.com> wrote:
>
> Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
> declaration time rather than being fixed for all declarations. This will
> be used in a follow-up commit to declare an cache in x86 with a capacity
> of 512+ objects without having to increase the capacity of all caches in
> KVM.
>
> This change requires each cache now specify its capacity at runtime,
> since the cache struct itself no longer has a fixed capacity known at
> compile time. To protect against someone accidentally defining a
> kvm_mmu_memory_cache struct directly (without the extra storage), this
> commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
>
> In order to support different capacities, this commit changes the
> objects pointer array to be dynamically allocated the first time the
> cache is topped-up.
>
> An alternative would be to lay out the objects array after the
> kvm_mmu_memory_cache struct, which can be done at compile time. But that
> change, unfortunately, adds some grottiness to arm64 and riscv, which
> uses a function-local (i.e. stack-allocated) kvm_mmu_memory_cache
> struct. Since C does not allow anonymous structs in functions, the new
> wrapper struct that contains kvm_mmu_memory_cache and the objects
> pointer array, must be named, which means dealing with an outer and
> inner struct. The outer struct can't be dropped since then there would
> be no guarantee the kvm_mmu_memory_cache struct and objects array would
> be laid out consecutively on the stack.
You may want to drop this paragraph. Someone interested in the history
can find it on the list.
>
> No functional change intended.
>
> Signed-off-by: David Matlack <dmatlack@google.com>
> ---
> arch/arm64/kvm/arm.c | 1 +
> arch/arm64/kvm/mmu.c | 5 ++++-
> arch/mips/kvm/mips.c | 2 ++
> arch/riscv/kvm/mmu.c | 8 ++++----
> arch/riscv/kvm/vcpu.c | 1 +
> arch/x86/kvm/mmu/mmu.c | 9 +++++++++
> include/linux/kvm_types.h | 9 +++++++--
> virt/kvm/kvm_main.c | 20 ++++++++++++++++++--
> 8 files changed, 46 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 7fceb855fa71..aa1e0c1659d4 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -320,6 +320,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> vcpu->arch.target = -1;
> bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
>
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
>
> /* Set up the timer */
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 53ae2c0640bc..2f2ef6b60ff4 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> {
> phys_addr_t addr;
> int ret = 0;
> - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> + struct kvm_mmu_memory_cache cache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
> + };
> struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> KVM_PGTABLE_PROT_R |
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index a25e0b73ee70..45c7179144dc 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -387,6 +387,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> if (err)
> goto out_free_gebase;
>
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> +
> return 0;
>
> out_free_gebase:
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index f80a34fbf102..8c2338ecc246 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -347,10 +347,10 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
> int ret = 0;
> unsigned long pfn;
> phys_addr_t addr, end;
> - struct kvm_mmu_memory_cache pcache;
> -
> - memset(&pcache, 0, sizeof(pcache));
> - pcache.gfp_zero = __GFP_ZERO;
> + struct kvm_mmu_memory_cache pcache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
> + };
>
> end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
> pfn = __phys_to_pfn(hpa);
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 6785aef4cbd4..bbcb9d4a04fb 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -94,6 +94,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
>
> /* Mark this VCPU never ran */
> vcpu->arch.ran_atleast_once = false;
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
>
> /* Setup ISA features available to VCPU */
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 4b40fa2e27eb..dad7e19ef8ed 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5803,12 +5803,21 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
> {
> int ret;
>
> + vcpu->arch.mmu_pte_list_desc_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
>
> + vcpu->arch.mmu_page_header_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
>
> + vcpu->arch.mmu_shadowed_info_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> +
> + vcpu->arch.mmu_shadow_page_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
>
> vcpu->arch.mmu = &vcpu->arch.root_mmu;
> diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> index ac1ebb37a0ff..549103a4f7bc 100644
> --- a/include/linux/kvm_types.h
> +++ b/include/linux/kvm_types.h
> @@ -83,14 +83,19 @@ struct gfn_to_pfn_cache {
> * MMU flows is problematic, as is triggering reclaim, I/O, etc... while
> * holding MMU locks. Note, these caches act more like prefetch buffers than
> * classical caches, i.e. objects are not returned to the cache on being freed.
> + *
> + * The storage for the cache object pointers is allocated dynamically when the
> + * cache is topped-up. The capacity field defines the number of object pointers
> + * available after the struct.
> */
> struct kvm_mmu_memory_cache {
> int nobjs;
> + int capacity;
> gfp_t gfp_zero;
> struct kmem_cache *kmem_cache;
> - void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
> + void **objects;
> };
> -#endif
> +#endif /* KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE */
One thing that is missing here (and was already missing) is to make it
plain that kvm_mmu_memory_cache can only be used in contexts where
there are no concurrent accesses to the cache.
>
> #define HALT_POLL_HIST_COUNT 32
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e089db822c12..264e4107e06f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -371,12 +371,23 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
>
> int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> {
> + gfp_t gfp = GFP_KERNEL_ACCOUNT;
> void *obj;
>
> if (mc->nobjs >= min)
> return 0;
> - while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
> - obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
> +
> + if (WARN_ON(mc->capacity == 0))
> + return -EINVAL;
> +
> + if (!mc->objects) {
> + mc->objects = kvmalloc_array(sizeof(void *), mc->capacity, gfp);
> + if (!mc->objects)
> + return -ENOMEM;
> + }
> +
> + while (mc->nobjs < mc->capacity) {
> + obj = mmu_memory_cache_alloc_obj(mc, gfp);
> if (!obj)
> return mc->nobjs >= min ? 0 : -ENOMEM;
> mc->objects[mc->nobjs++] = obj;
> @@ -397,6 +408,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> else
> free_page((unsigned long)mc->objects[--mc->nobjs]);
> }
> +
> + kvfree(mc->objects);
> +
> + /* Note, must set to NULL to avoid use-after-free in the next top-up. */
> + mc->objects = NULL;
> }
>
> void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
Otherwise:
Reviewed-by: Marc Zyngier <maz@kernel.org>
M.
--
Without deviation from the norm, progress is not possible.
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
@ 2022-05-15 11:42 ` Marc Zyngier
0 siblings, 0 replies; 60+ messages in thread
From: Marc Zyngier @ 2022-05-15 11:42 UTC (permalink / raw)
To: David Matlack
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, Paolo Bonzini, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
On Fri, 13 May 2022 21:28:18 +0100,
David Matlack <dmatlack@google.com> wrote:
>
> Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
> declaration time rather than being fixed for all declarations. This will
> be used in a follow-up commit to declare an cache in x86 with a capacity
> of 512+ objects without having to increase the capacity of all caches in
> KVM.
>
> This change requires each cache now specify its capacity at runtime,
> since the cache struct itself no longer has a fixed capacity known at
> compile time. To protect against someone accidentally defining a
> kvm_mmu_memory_cache struct directly (without the extra storage), this
> commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
>
> In order to support different capacities, this commit changes the
> objects pointer array to be dynamically allocated the first time the
> cache is topped-up.
>
> An alternative would be to lay out the objects array after the
> kvm_mmu_memory_cache struct, which can be done at compile time. But that
> change, unfortunately, adds some grottiness to arm64 and riscv, which
> uses a function-local (i.e. stack-allocated) kvm_mmu_memory_cache
> struct. Since C does not allow anonymous structs in functions, the new
> wrapper struct that contains kvm_mmu_memory_cache and the objects
> pointer array, must be named, which means dealing with an outer and
> inner struct. The outer struct can't be dropped since then there would
> be no guarantee the kvm_mmu_memory_cache struct and objects array would
> be laid out consecutively on the stack.
You may want to drop this paragraph. Someone interested in the history
can find it on the list.
>
> No functional change intended.
>
> Signed-off-by: David Matlack <dmatlack@google.com>
> ---
> arch/arm64/kvm/arm.c | 1 +
> arch/arm64/kvm/mmu.c | 5 ++++-
> arch/mips/kvm/mips.c | 2 ++
> arch/riscv/kvm/mmu.c | 8 ++++----
> arch/riscv/kvm/vcpu.c | 1 +
> arch/x86/kvm/mmu/mmu.c | 9 +++++++++
> include/linux/kvm_types.h | 9 +++++++--
> virt/kvm/kvm_main.c | 20 ++++++++++++++++++--
> 8 files changed, 46 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 7fceb855fa71..aa1e0c1659d4 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -320,6 +320,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> vcpu->arch.target = -1;
> bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
>
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
>
> /* Set up the timer */
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 53ae2c0640bc..2f2ef6b60ff4 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> {
> phys_addr_t addr;
> int ret = 0;
> - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> + struct kvm_mmu_memory_cache cache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
> + };
> struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> KVM_PGTABLE_PROT_R |
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index a25e0b73ee70..45c7179144dc 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -387,6 +387,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> if (err)
> goto out_free_gebase;
>
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> +
> return 0;
>
> out_free_gebase:
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index f80a34fbf102..8c2338ecc246 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -347,10 +347,10 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
> int ret = 0;
> unsigned long pfn;
> phys_addr_t addr, end;
> - struct kvm_mmu_memory_cache pcache;
> -
> - memset(&pcache, 0, sizeof(pcache));
> - pcache.gfp_zero = __GFP_ZERO;
> + struct kvm_mmu_memory_cache pcache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
> + };
>
> end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
> pfn = __phys_to_pfn(hpa);
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 6785aef4cbd4..bbcb9d4a04fb 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -94,6 +94,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
>
> /* Mark this VCPU never ran */
> vcpu->arch.ran_atleast_once = false;
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
>
> /* Setup ISA features available to VCPU */
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 4b40fa2e27eb..dad7e19ef8ed 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5803,12 +5803,21 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
> {
> int ret;
>
> + vcpu->arch.mmu_pte_list_desc_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
>
> + vcpu->arch.mmu_page_header_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
>
> + vcpu->arch.mmu_shadowed_info_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> +
> + vcpu->arch.mmu_shadow_page_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
>
> vcpu->arch.mmu = &vcpu->arch.root_mmu;
> diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> index ac1ebb37a0ff..549103a4f7bc 100644
> --- a/include/linux/kvm_types.h
> +++ b/include/linux/kvm_types.h
> @@ -83,14 +83,19 @@ struct gfn_to_pfn_cache {
> * MMU flows is problematic, as is triggering reclaim, I/O, etc... while
> * holding MMU locks. Note, these caches act more like prefetch buffers than
> * classical caches, i.e. objects are not returned to the cache on being freed.
> + *
> + * The storage for the cache object pointers is allocated dynamically when the
> + * cache is topped-up. The capacity field defines the number of object pointers
> + * available after the struct.
> */
> struct kvm_mmu_memory_cache {
> int nobjs;
> + int capacity;
> gfp_t gfp_zero;
> struct kmem_cache *kmem_cache;
> - void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
> + void **objects;
> };
> -#endif
> +#endif /* KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE */
One thing that is missing here (and was already missing) is to make it
plain that kvm_mmu_memory_cache can only be used in contexts where
there are no concurrent accesses to the cache.
>
> #define HALT_POLL_HIST_COUNT 32
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e089db822c12..264e4107e06f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -371,12 +371,23 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
>
> int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> {
> + gfp_t gfp = GFP_KERNEL_ACCOUNT;
> void *obj;
>
> if (mc->nobjs >= min)
> return 0;
> - while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
> - obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
> +
> + if (WARN_ON(mc->capacity == 0))
> + return -EINVAL;
> +
> + if (!mc->objects) {
> + mc->objects = kvmalloc_array(sizeof(void *), mc->capacity, gfp);
> + if (!mc->objects)
> + return -ENOMEM;
> + }
> +
> + while (mc->nobjs < mc->capacity) {
> + obj = mmu_memory_cache_alloc_obj(mc, gfp);
> if (!obj)
> return mc->nobjs >= min ? 0 : -ENOMEM;
> mc->objects[mc->nobjs++] = obj;
> @@ -397,6 +408,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> else
> free_page((unsigned long)mc->objects[--mc->nobjs]);
> }
> +
> + kvfree(mc->objects);
> +
> + /* Note, must set to NULL to avoid use-after-free in the next top-up. */
> + mc->objects = NULL;
> }
>
> void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
Otherwise:
Reviewed-by: Marc Zyngier <maz@kernel.org>
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
2022-05-13 20:28 ` David Matlack
@ 2022-05-16 3:31 ` Anup Patel
-1 siblings, 0 replies; 60+ messages in thread
From: Anup Patel @ 2022-05-16 3:31 UTC (permalink / raw)
To: David Matlack
Cc: Paolo Bonzini, Marc Zyngier, Huacai Chen, Aleksandar Markovic,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, Maciej S. Szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan
On Sat, May 14, 2022 at 1:59 AM David Matlack <dmatlack@google.com> wrote:
>
> Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
> declaration time rather than being fixed for all declarations. This will
> be used in a follow-up commit to declare an cache in x86 with a capacity
> of 512+ objects without having to increase the capacity of all caches in
> KVM.
>
> This change requires each cache now specify its capacity at runtime,
> since the cache struct itself no longer has a fixed capacity known at
> compile time. To protect against someone accidentally defining a
> kvm_mmu_memory_cache struct directly (without the extra storage), this
> commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
>
> In order to support different capacities, this commit changes the
> objects pointer array to be dynamically allocated the first time the
> cache is topped-up.
>
> An alternative would be to lay out the objects array after the
> kvm_mmu_memory_cache struct, which can be done at compile time. But that
> change, unfortunately, adds some grottiness to arm64 and riscv, which
> uses a function-local (i.e. stack-allocated) kvm_mmu_memory_cache
> struct. Since C does not allow anonymous structs in functions, the new
> wrapper struct that contains kvm_mmu_memory_cache and the objects
> pointer array, must be named, which means dealing with an outer and
> inner struct. The outer struct can't be dropped since then there would
> be no guarantee the kvm_mmu_memory_cache struct and objects array would
> be laid out consecutively on the stack.
>
> No functional change intended.
>
> Signed-off-by: David Matlack <dmatlack@google.com>
Overall, this looks good to me. I wanted to try this patch with KVM RISC-V
but there are conflicts in include/linux/kvm_types.h and virt/kvm/kvm_main.c
Please take a look.
Regards,
Anup
> ---
> arch/arm64/kvm/arm.c | 1 +
> arch/arm64/kvm/mmu.c | 5 ++++-
> arch/mips/kvm/mips.c | 2 ++
> arch/riscv/kvm/mmu.c | 8 ++++----
> arch/riscv/kvm/vcpu.c | 1 +
> arch/x86/kvm/mmu/mmu.c | 9 +++++++++
> include/linux/kvm_types.h | 9 +++++++--
> virt/kvm/kvm_main.c | 20 ++++++++++++++++++--
> 8 files changed, 46 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 7fceb855fa71..aa1e0c1659d4 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -320,6 +320,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> vcpu->arch.target = -1;
> bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
>
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
>
> /* Set up the timer */
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 53ae2c0640bc..2f2ef6b60ff4 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> {
> phys_addr_t addr;
> int ret = 0;
> - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> + struct kvm_mmu_memory_cache cache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
> + };
> struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> KVM_PGTABLE_PROT_R |
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index a25e0b73ee70..45c7179144dc 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -387,6 +387,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> if (err)
> goto out_free_gebase;
>
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> +
> return 0;
>
> out_free_gebase:
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index f80a34fbf102..8c2338ecc246 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -347,10 +347,10 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
> int ret = 0;
> unsigned long pfn;
> phys_addr_t addr, end;
> - struct kvm_mmu_memory_cache pcache;
> -
> - memset(&pcache, 0, sizeof(pcache));
> - pcache.gfp_zero = __GFP_ZERO;
> + struct kvm_mmu_memory_cache pcache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
> + };
>
> end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
> pfn = __phys_to_pfn(hpa);
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 6785aef4cbd4..bbcb9d4a04fb 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -94,6 +94,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
>
> /* Mark this VCPU never ran */
> vcpu->arch.ran_atleast_once = false;
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
>
> /* Setup ISA features available to VCPU */
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 4b40fa2e27eb..dad7e19ef8ed 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5803,12 +5803,21 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
> {
> int ret;
>
> + vcpu->arch.mmu_pte_list_desc_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
>
> + vcpu->arch.mmu_page_header_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
>
> + vcpu->arch.mmu_shadowed_info_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> +
> + vcpu->arch.mmu_shadow_page_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
>
> vcpu->arch.mmu = &vcpu->arch.root_mmu;
> diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> index ac1ebb37a0ff..549103a4f7bc 100644
> --- a/include/linux/kvm_types.h
> +++ b/include/linux/kvm_types.h
> @@ -83,14 +83,19 @@ struct gfn_to_pfn_cache {
> * MMU flows is problematic, as is triggering reclaim, I/O, etc... while
> * holding MMU locks. Note, these caches act more like prefetch buffers than
> * classical caches, i.e. objects are not returned to the cache on being freed.
> + *
> + * The storage for the cache object pointers is allocated dynamically when the
> + * cache is topped-up. The capacity field defines the number of object pointers
> + * available after the struct.
> */
> struct kvm_mmu_memory_cache {
> int nobjs;
> + int capacity;
> gfp_t gfp_zero;
> struct kmem_cache *kmem_cache;
> - void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
> + void **objects;
> };
> -#endif
> +#endif /* KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE */
>
> #define HALT_POLL_HIST_COUNT 32
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e089db822c12..264e4107e06f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -371,12 +371,23 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
>
> int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> {
> + gfp_t gfp = GFP_KERNEL_ACCOUNT;
> void *obj;
>
> if (mc->nobjs >= min)
> return 0;
> - while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
> - obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
> +
> + if (WARN_ON(mc->capacity == 0))
> + return -EINVAL;
> +
> + if (!mc->objects) {
> + mc->objects = kvmalloc_array(sizeof(void *), mc->capacity, gfp);
> + if (!mc->objects)
> + return -ENOMEM;
> + }
> +
> + while (mc->nobjs < mc->capacity) {
> + obj = mmu_memory_cache_alloc_obj(mc, gfp);
> if (!obj)
> return mc->nobjs >= min ? 0 : -ENOMEM;
> mc->objects[mc->nobjs++] = obj;
> @@ -397,6 +408,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> else
> free_page((unsigned long)mc->objects[--mc->nobjs]);
> }
> +
> + kvfree(mc->objects);
> +
> + /* Note, must set to NULL to avoid use-after-free in the next top-up. */
> + mc->objects = NULL;
> }
>
> void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> --
> 2.36.0.550.gb090851708-goog
>
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
@ 2022-05-16 3:31 ` Anup Patel
0 siblings, 0 replies; 60+ messages in thread
From: Anup Patel @ 2022-05-16 3:31 UTC (permalink / raw)
To: David Matlack
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, Paolo Bonzini, Maciej S. Szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
On Sat, May 14, 2022 at 1:59 AM David Matlack <dmatlack@google.com> wrote:
>
> Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
> declaration time rather than being fixed for all declarations. This will
> be used in a follow-up commit to declare an cache in x86 with a capacity
> of 512+ objects without having to increase the capacity of all caches in
> KVM.
>
> This change requires each cache now specify its capacity at runtime,
> since the cache struct itself no longer has a fixed capacity known at
> compile time. To protect against someone accidentally defining a
> kvm_mmu_memory_cache struct directly (without the extra storage), this
> commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
>
> In order to support different capacities, this commit changes the
> objects pointer array to be dynamically allocated the first time the
> cache is topped-up.
>
> An alternative would be to lay out the objects array after the
> kvm_mmu_memory_cache struct, which can be done at compile time. But that
> change, unfortunately, adds some grottiness to arm64 and riscv, which
> uses a function-local (i.e. stack-allocated) kvm_mmu_memory_cache
> struct. Since C does not allow anonymous structs in functions, the new
> wrapper struct that contains kvm_mmu_memory_cache and the objects
> pointer array, must be named, which means dealing with an outer and
> inner struct. The outer struct can't be dropped since then there would
> be no guarantee the kvm_mmu_memory_cache struct and objects array would
> be laid out consecutively on the stack.
>
> No functional change intended.
>
> Signed-off-by: David Matlack <dmatlack@google.com>
Overall, this looks good to me. I wanted to try this patch with KVM RISC-V
but there are conflicts in include/linux/kvm_types.h and virt/kvm/kvm_main.c
Please take a look.
Regards,
Anup
> ---
> arch/arm64/kvm/arm.c | 1 +
> arch/arm64/kvm/mmu.c | 5 ++++-
> arch/mips/kvm/mips.c | 2 ++
> arch/riscv/kvm/mmu.c | 8 ++++----
> arch/riscv/kvm/vcpu.c | 1 +
> arch/x86/kvm/mmu/mmu.c | 9 +++++++++
> include/linux/kvm_types.h | 9 +++++++--
> virt/kvm/kvm_main.c | 20 ++++++++++++++++++--
> 8 files changed, 46 insertions(+), 9 deletions(-)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 7fceb855fa71..aa1e0c1659d4 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -320,6 +320,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> vcpu->arch.target = -1;
> bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
>
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
>
> /* Set up the timer */
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 53ae2c0640bc..2f2ef6b60ff4 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> {
> phys_addr_t addr;
> int ret = 0;
> - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> + struct kvm_mmu_memory_cache cache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
> + };
> struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> KVM_PGTABLE_PROT_R |
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index a25e0b73ee70..45c7179144dc 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -387,6 +387,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> if (err)
> goto out_free_gebase;
>
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> +
> return 0;
>
> out_free_gebase:
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index f80a34fbf102..8c2338ecc246 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -347,10 +347,10 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
> int ret = 0;
> unsigned long pfn;
> phys_addr_t addr, end;
> - struct kvm_mmu_memory_cache pcache;
> -
> - memset(&pcache, 0, sizeof(pcache));
> - pcache.gfp_zero = __GFP_ZERO;
> + struct kvm_mmu_memory_cache pcache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
> + };
>
> end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
> pfn = __phys_to_pfn(hpa);
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index 6785aef4cbd4..bbcb9d4a04fb 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -94,6 +94,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
>
> /* Mark this VCPU never ran */
> vcpu->arch.ran_atleast_once = false;
> + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
>
> /* Setup ISA features available to VCPU */
> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> index 4b40fa2e27eb..dad7e19ef8ed 100644
> --- a/arch/x86/kvm/mmu/mmu.c
> +++ b/arch/x86/kvm/mmu/mmu.c
> @@ -5803,12 +5803,21 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
> {
> int ret;
>
> + vcpu->arch.mmu_pte_list_desc_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
>
> + vcpu->arch.mmu_page_header_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
>
> + vcpu->arch.mmu_shadowed_info_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> +
> + vcpu->arch.mmu_shadow_page_cache.capacity =
> + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
>
> vcpu->arch.mmu = &vcpu->arch.root_mmu;
> diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> index ac1ebb37a0ff..549103a4f7bc 100644
> --- a/include/linux/kvm_types.h
> +++ b/include/linux/kvm_types.h
> @@ -83,14 +83,19 @@ struct gfn_to_pfn_cache {
> * MMU flows is problematic, as is triggering reclaim, I/O, etc... while
> * holding MMU locks. Note, these caches act more like prefetch buffers than
> * classical caches, i.e. objects are not returned to the cache on being freed.
> + *
> + * The storage for the cache object pointers is allocated dynamically when the
> + * cache is topped-up. The capacity field defines the number of object pointers
> + * available after the struct.
> */
> struct kvm_mmu_memory_cache {
> int nobjs;
> + int capacity;
> gfp_t gfp_zero;
> struct kmem_cache *kmem_cache;
> - void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
> + void **objects;
> };
> -#endif
> +#endif /* KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE */
>
> #define HALT_POLL_HIST_COUNT 32
>
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e089db822c12..264e4107e06f 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -371,12 +371,23 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
>
> int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> {
> + gfp_t gfp = GFP_KERNEL_ACCOUNT;
> void *obj;
>
> if (mc->nobjs >= min)
> return 0;
> - while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
> - obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
> +
> + if (WARN_ON(mc->capacity == 0))
> + return -EINVAL;
> +
> + if (!mc->objects) {
> + mc->objects = kvmalloc_array(sizeof(void *), mc->capacity, gfp);
> + if (!mc->objects)
> + return -ENOMEM;
> + }
> +
> + while (mc->nobjs < mc->capacity) {
> + obj = mmu_memory_cache_alloc_obj(mc, gfp);
> if (!obj)
> return mc->nobjs >= min ? 0 : -ENOMEM;
> mc->objects[mc->nobjs++] = obj;
> @@ -397,6 +408,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> else
> free_page((unsigned long)mc->objects[--mc->nobjs]);
> }
> +
> + kvfree(mc->objects);
> +
> + /* Note, must set to NULL to avoid use-after-free in the next top-up. */
> + mc->objects = NULL;
> }
>
> void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> --
> 2.36.0.550.gb090851708-goog
>
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 03/21] KVM: x86/mmu: Derive shadow MMU page role from parent
2022-05-13 20:28 ` David Matlack
@ 2022-05-16 6:54 ` Lai Jiangshan
-1 siblings, 0 replies; 60+ messages in thread
From: Lai Jiangshan @ 2022-05-16 6:54 UTC (permalink / raw)
To: David Matlack
Cc: Paolo Bonzini, Marc Zyngier, Huacai Chen, Aleksandar Markovic,
Anup Patel, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Sean Christopherson, Andrew Jones, Ben Gardon, Peter Xu,
Maciej S . Szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner
On Sat, May 14, 2022 at 4:28 AM David Matlack <dmatlack@google.com> wrote:
> -static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva,
> +static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
> u8 level, bool direct)
> {
> + union kvm_mmu_page_role role;
> struct kvm_mmu_page *sp;
>
> - sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL);
> + role = vcpu->arch.mmu->root_role;
> + role.level = level;
> + role.direct = direct;
> + role.access = ACC_ALL;
> +
> + if (role.has_4_byte_gpte)
> + role.quadrant = quadrant;
> +
> + if (level <= vcpu->arch.mmu->cpu_role.base.level)
> + role.passthrough = 0;
> +
+ role.level = level;
+
+ if (role.has_4_byte_gpte)
+ role.quadrant = quadrant;
Only these lines are needed because of mmu->pae_root, others are
the same as vcpu->arch.mmu->root_role.
The argument @direct is vcpu->arch.mmu->root_role.direct.
vcpu->arch.mmu->root_role.access is always set to be ACC_ALL.
vcpu->arch.mmu->root_role.passthrough is 0 when mmu->pae_root is used.
Or if vcpu->arch.mmu->root_role.passthrough is 1, @level must be 5
and vcpu->arch.mmu->cpu_role.base.level must be 4, the code here
is useless.
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 03/21] KVM: x86/mmu: Derive shadow MMU page role from parent
@ 2022-05-16 6:54 ` Lai Jiangshan
0 siblings, 0 replies; 60+ messages in thread
From: Lai Jiangshan @ 2022-05-16 6:54 UTC (permalink / raw)
To: David Matlack
Cc: Marc Zyngier, Albert Ou,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Huacai Chen, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, Paolo Bonzini, Maciej S . Szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
On Sat, May 14, 2022 at 4:28 AM David Matlack <dmatlack@google.com> wrote:
> -static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva,
> +static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
> u8 level, bool direct)
> {
> + union kvm_mmu_page_role role;
> struct kvm_mmu_page *sp;
>
> - sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL);
> + role = vcpu->arch.mmu->root_role;
> + role.level = level;
> + role.direct = direct;
> + role.access = ACC_ALL;
> +
> + if (role.has_4_byte_gpte)
> + role.quadrant = quadrant;
> +
> + if (level <= vcpu->arch.mmu->cpu_role.base.level)
> + role.passthrough = 0;
> +
+ role.level = level;
+
+ if (role.has_4_byte_gpte)
+ role.quadrant = quadrant;
Only these lines are needed because of mmu->pae_root, others are
the same as vcpu->arch.mmu->root_role.
The argument @direct is vcpu->arch.mmu->root_role.direct.
vcpu->arch.mmu->root_role.access is always set to be ACC_ALL.
vcpu->arch.mmu->root_role.passthrough is 0 when mmu->pae_root is used.
Or if vcpu->arch.mmu->root_role.passthrough is 1, @level must be 5
and vcpu->arch.mmu->cpu_role.base.level must be 4, the code here
is useless.
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
2022-05-13 20:28 ` David Matlack
@ 2022-05-16 14:49 ` Sean Christopherson
-1 siblings, 0 replies; 60+ messages in thread
From: Sean Christopherson @ 2022-05-16 14:49 UTC (permalink / raw)
To: David Matlack
Cc: Paolo Bonzini, Marc Zyngier, Huacai Chen, Aleksandar Markovic,
Anup Patel, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan
On Fri, May 13, 2022, David Matlack wrote:
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 53ae2c0640bc..2f2ef6b60ff4 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> {
> phys_addr_t addr;
> int ret = 0;
> - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> + struct kvm_mmu_memory_cache cache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
I dislike requiring all users to specificy the capacity. It largely defeats the
purpose of KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, and bleeds details into code that
really doesn't care all that much about the details.
Rather than force the capacity to be set before topup, what about adding a custom
capacity topup helper? That allows keeping a default capacity, better documents
the caches that are special, and provides an opportunity to sanity check that the
capacity isn't incorrectly changed by the user.
And then I believe this code becomes:
struct kvm_mmu_memory_cache cache = { .gfp_zero = __GFP_ZERO };
E.g. (completely untested)
static int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc,
int capacity, int min)
{
gfp_t gfp = GFP_KERNEL_ACCOUNT;
void *obj;
if (mc->nobjs >= min)
return 0;
if (likely(mc->capacity)) {
if (WARN_ON_ONCE(mc->capacity != capacity || !mc->objects))
return -EIO;
} else {
mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
if (!mc->objects)
return -ENOMEM;
mc->capacity = capacity;
}
while (mc->nobjs < mc->capacity) {
obj = mmu_memory_cache_alloc_obj(mc, gfp);
if (!obj)
return mc->nobjs >= min ? 0 : -ENOMEM;
mc->objects[mc->nobjs++] = obj;
}
return 0;
}
int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
{
const int capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
return __kvm_mmu_topup_memory_cache(mc, capacity, min);
}
int kvm_mmu_topup_custom_memory_cache(struct kvm_mmu_memory_cache *mc,
int capacity)
{
return __kvm_mmu_topup_memory_cache(mc, capacity, capacity);
}
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
@ 2022-05-16 14:49 ` Sean Christopherson
0 siblings, 0 replies; 60+ messages in thread
From: Sean Christopherson @ 2022-05-16 14:49 UTC (permalink / raw)
To: David Matlack
Cc: Marc Zyngier, Albert Ou,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, Paolo Bonzini, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
On Fri, May 13, 2022, David Matlack wrote:
> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> index 53ae2c0640bc..2f2ef6b60ff4 100644
> --- a/arch/arm64/kvm/mmu.c
> +++ b/arch/arm64/kvm/mmu.c
> @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> {
> phys_addr_t addr;
> int ret = 0;
> - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> + struct kvm_mmu_memory_cache cache = {
> + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> + .gfp_zero = __GFP_ZERO,
I dislike requiring all users to specificy the capacity. It largely defeats the
purpose of KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, and bleeds details into code that
really doesn't care all that much about the details.
Rather than force the capacity to be set before topup, what about adding a custom
capacity topup helper? That allows keeping a default capacity, better documents
the caches that are special, and provides an opportunity to sanity check that the
capacity isn't incorrectly changed by the user.
And then I believe this code becomes:
struct kvm_mmu_memory_cache cache = { .gfp_zero = __GFP_ZERO };
E.g. (completely untested)
static int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc,
int capacity, int min)
{
gfp_t gfp = GFP_KERNEL_ACCOUNT;
void *obj;
if (mc->nobjs >= min)
return 0;
if (likely(mc->capacity)) {
if (WARN_ON_ONCE(mc->capacity != capacity || !mc->objects))
return -EIO;
} else {
mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
if (!mc->objects)
return -ENOMEM;
mc->capacity = capacity;
}
while (mc->nobjs < mc->capacity) {
obj = mmu_memory_cache_alloc_obj(mc, gfp);
if (!obj)
return mc->nobjs >= min ? 0 : -ENOMEM;
mc->objects[mc->nobjs++] = obj;
}
return 0;
}
int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
{
const int capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
return __kvm_mmu_topup_memory_cache(mc, capacity, min);
}
int kvm_mmu_topup_custom_memory_cache(struct kvm_mmu_memory_cache *mc,
int capacity)
{
return __kvm_mmu_topup_memory_cache(mc, capacity, capacity);
}
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
2022-05-16 14:49 ` Sean Christopherson
@ 2022-05-16 16:39 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-16 16:39 UTC (permalink / raw)
To: Sean Christopherson
Cc: Paolo Bonzini, Marc Zyngier, Huacai Chen, Aleksandar Markovic,
Anup Patel, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan
On Mon, May 16, 2022 at 7:49 AM Sean Christopherson <seanjc@google.com> wrote:
>
> On Fri, May 13, 2022, David Matlack wrote:
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 53ae2c0640bc..2f2ef6b60ff4 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> > {
> > phys_addr_t addr;
> > int ret = 0;
> > - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> > + struct kvm_mmu_memory_cache cache = {
> > + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> > + .gfp_zero = __GFP_ZERO,
>
> I dislike requiring all users to specificy the capacity. It largely defeats the
> purpose of KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, and bleeds details into code that
> really doesn't care all that much about the details.
>
> Rather than force the capacity to be set before topup, what about adding a custom
> capacity topup helper? That allows keeping a default capacity, better documents
> the caches that are special, and provides an opportunity to sanity check that the
> capacity isn't incorrectly changed by the user.
Even simpler: If mc->capacity is 0 in topup, set it to
KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE.
This is what I had before when I was laying out the storage for
objects in a separate array. It was risky then because it was too easy
for someone to accidentally corrupt memory (call topup with
capacity==0 but without allocating the objects array). Now that topup
takes care of allocation automatically, that risk is gone.
>
> And then I believe this code becomes:
>
> struct kvm_mmu_memory_cache cache = { .gfp_zero = __GFP_ZERO };
>
> E.g. (completely untested)
>
> static int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc,
> int capacity, int min)
> {
> gfp_t gfp = GFP_KERNEL_ACCOUNT;
> void *obj;
>
> if (mc->nobjs >= min)
> return 0;
>
> if (likely(mc->capacity)) {
> if (WARN_ON_ONCE(mc->capacity != capacity || !mc->objects))
> return -EIO;
> } else {
> mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
> if (!mc->objects)
> return -ENOMEM;
>
> mc->capacity = capacity;
> }
>
> while (mc->nobjs < mc->capacity) {
> obj = mmu_memory_cache_alloc_obj(mc, gfp);
> if (!obj)
> return mc->nobjs >= min ? 0 : -ENOMEM;
> mc->objects[mc->nobjs++] = obj;
> }
> return 0;
> }
>
> int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> {
> const int capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
>
> return __kvm_mmu_topup_memory_cache(mc, capacity, min);
> }
>
> int kvm_mmu_topup_custom_memory_cache(struct kvm_mmu_memory_cache *mc,
> int capacity)
> {
> return __kvm_mmu_topup_memory_cache(mc, capacity, capacity);
> }
>
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
@ 2022-05-16 16:39 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-16 16:39 UTC (permalink / raw)
To: Sean Christopherson
Cc: Marc Zyngier, Albert Ou,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, Paolo Bonzini, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
On Mon, May 16, 2022 at 7:49 AM Sean Christopherson <seanjc@google.com> wrote:
>
> On Fri, May 13, 2022, David Matlack wrote:
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 53ae2c0640bc..2f2ef6b60ff4 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> > {
> > phys_addr_t addr;
> > int ret = 0;
> > - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> > + struct kvm_mmu_memory_cache cache = {
> > + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> > + .gfp_zero = __GFP_ZERO,
>
> I dislike requiring all users to specificy the capacity. It largely defeats the
> purpose of KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, and bleeds details into code that
> really doesn't care all that much about the details.
>
> Rather than force the capacity to be set before topup, what about adding a custom
> capacity topup helper? That allows keeping a default capacity, better documents
> the caches that are special, and provides an opportunity to sanity check that the
> capacity isn't incorrectly changed by the user.
Even simpler: If mc->capacity is 0 in topup, set it to
KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE.
This is what I had before when I was laying out the storage for
objects in a separate array. It was risky then because it was too easy
for someone to accidentally corrupt memory (call topup with
capacity==0 but without allocating the objects array). Now that topup
takes care of allocation automatically, that risk is gone.
>
> And then I believe this code becomes:
>
> struct kvm_mmu_memory_cache cache = { .gfp_zero = __GFP_ZERO };
>
> E.g. (completely untested)
>
> static int __kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc,
> int capacity, int min)
> {
> gfp_t gfp = GFP_KERNEL_ACCOUNT;
> void *obj;
>
> if (mc->nobjs >= min)
> return 0;
>
> if (likely(mc->capacity)) {
> if (WARN_ON_ONCE(mc->capacity != capacity || !mc->objects))
> return -EIO;
> } else {
> mc->objects = kvmalloc_array(sizeof(void *), capacity, gfp);
> if (!mc->objects)
> return -ENOMEM;
>
> mc->capacity = capacity;
> }
>
> while (mc->nobjs < mc->capacity) {
> obj = mmu_memory_cache_alloc_obj(mc, gfp);
> if (!obj)
> return mc->nobjs >= min ? 0 : -ENOMEM;
> mc->objects[mc->nobjs++] = obj;
> }
> return 0;
> }
>
> int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> {
> const int capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
>
> return __kvm_mmu_topup_memory_cache(mc, capacity, min);
> }
>
> int kvm_mmu_topup_custom_memory_cache(struct kvm_mmu_memory_cache *mc,
> int capacity)
> {
> return __kvm_mmu_topup_memory_cache(mc, capacity, capacity);
> }
>
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
2022-05-16 16:39 ` David Matlack
@ 2022-05-16 17:53 ` Sean Christopherson
-1 siblings, 0 replies; 60+ messages in thread
From: Sean Christopherson @ 2022-05-16 17:53 UTC (permalink / raw)
To: David Matlack
Cc: Paolo Bonzini, Marc Zyngier, Huacai Chen, Aleksandar Markovic,
Anup Patel, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Andrew Jones, Ben Gardon, Peter Xu, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan
On Mon, May 16, 2022, David Matlack wrote:
> On Mon, May 16, 2022 at 7:49 AM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Fri, May 13, 2022, David Matlack wrote:
> > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > > index 53ae2c0640bc..2f2ef6b60ff4 100644
> > > --- a/arch/arm64/kvm/mmu.c
> > > +++ b/arch/arm64/kvm/mmu.c
> > > @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> > > {
> > > phys_addr_t addr;
> > > int ret = 0;
> > > - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> > > + struct kvm_mmu_memory_cache cache = {
> > > + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> > > + .gfp_zero = __GFP_ZERO,
> >
> > I dislike requiring all users to specificy the capacity. It largely defeats the
> > purpose of KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, and bleeds details into code that
> > really doesn't care all that much about the details.
> >
> > Rather than force the capacity to be set before topup, what about adding a custom
> > capacity topup helper? That allows keeping a default capacity, better documents
> > the caches that are special, and provides an opportunity to sanity check that the
> > capacity isn't incorrectly changed by the user.
>
> Even simpler: If mc->capacity is 0 in topup, set it to
> KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE.
I slightly prefer the explicit "custom" approach as it guards against topup being
called before the capacity is initialized, and against the capacity being changed
after the first topup call. It's a somewhat contrived reason since we obviously
rely on gfp_zero to be initialized before topup, but I like being more explicit
nonetheless.
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
@ 2022-05-16 17:53 ` Sean Christopherson
0 siblings, 0 replies; 60+ messages in thread
From: Sean Christopherson @ 2022-05-16 17:53 UTC (permalink / raw)
To: David Matlack
Cc: Marc Zyngier, Albert Ou,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, Paolo Bonzini, maciej.szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
On Mon, May 16, 2022, David Matlack wrote:
> On Mon, May 16, 2022 at 7:49 AM Sean Christopherson <seanjc@google.com> wrote:
> >
> > On Fri, May 13, 2022, David Matlack wrote:
> > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > > index 53ae2c0640bc..2f2ef6b60ff4 100644
> > > --- a/arch/arm64/kvm/mmu.c
> > > +++ b/arch/arm64/kvm/mmu.c
> > > @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> > > {
> > > phys_addr_t addr;
> > > int ret = 0;
> > > - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> > > + struct kvm_mmu_memory_cache cache = {
> > > + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> > > + .gfp_zero = __GFP_ZERO,
> >
> > I dislike requiring all users to specificy the capacity. It largely defeats the
> > purpose of KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE, and bleeds details into code that
> > really doesn't care all that much about the details.
> >
> > Rather than force the capacity to be set before topup, what about adding a custom
> > capacity topup helper? That allows keeping a default capacity, better documents
> > the caches that are special, and provides an opportunity to sanity check that the
> > capacity isn't incorrectly changed by the user.
>
> Even simpler: If mc->capacity is 0 in topup, set it to
> KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE.
I slightly prefer the explicit "custom" approach as it guards against topup being
called before the capacity is initialized, and against the capacity being changed
after the first topup call. It's a somewhat contrived reason since we obviously
rely on gfp_zero to be initialized before topup, but I like being more explicit
nonetheless.
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 03/21] KVM: x86/mmu: Derive shadow MMU page role from parent
2022-05-16 6:54 ` Lai Jiangshan
@ 2022-05-16 21:38 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-16 21:38 UTC (permalink / raw)
To: Lai Jiangshan
Cc: Paolo Bonzini, Marc Zyngier, Huacai Chen, Aleksandar Markovic,
Anup Patel, Paul Walmsley, Palmer Dabbelt, Albert Ou,
Sean Christopherson, Andrew Jones, Ben Gardon, Peter Xu,
Maciej S . Szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner
On Sun, May 15, 2022 at 11:55 PM Lai Jiangshan <jiangshanlai@gmail.com> wrote:
>
> On Sat, May 14, 2022 at 4:28 AM David Matlack <dmatlack@google.com> wrote:
>
> > -static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva,
> > +static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
> > u8 level, bool direct)
> > {
> > + union kvm_mmu_page_role role;
> > struct kvm_mmu_page *sp;
> >
> > - sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL);
> > + role = vcpu->arch.mmu->root_role;
> > + role.level = level;
> > + role.direct = direct;
> > + role.access = ACC_ALL;
> > +
> > + if (role.has_4_byte_gpte)
> > + role.quadrant = quadrant;
> > +
> > + if (level <= vcpu->arch.mmu->cpu_role.base.level)
> > + role.passthrough = 0;
> > +
>
>
>
> + role.level = level;
> +
> + if (role.has_4_byte_gpte)
> + role.quadrant = quadrant;
>
> Only these lines are needed because of mmu->pae_root, others are
> the same as vcpu->arch.mmu->root_role.
>
> The argument @direct is vcpu->arch.mmu->root_role.direct.
> vcpu->arch.mmu->root_role.access is always set to be ACC_ALL.
>
> vcpu->arch.mmu->root_role.passthrough is 0 when mmu->pae_root is used.
> Or if vcpu->arch.mmu->root_role.passthrough is 1, @level must be 5
> and vcpu->arch.mmu->cpu_role.base.level must be 4, the code here
> is useless.
Ah, thank you for the tip. That is cleaner.
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 03/21] KVM: x86/mmu: Derive shadow MMU page role from parent
@ 2022-05-16 21:38 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-16 21:38 UTC (permalink / raw)
To: Lai Jiangshan
Cc: Marc Zyngier, Albert Ou,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Huacai Chen, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, Paolo Bonzini, Maciej S . Szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
On Sun, May 15, 2022 at 11:55 PM Lai Jiangshan <jiangshanlai@gmail.com> wrote:
>
> On Sat, May 14, 2022 at 4:28 AM David Matlack <dmatlack@google.com> wrote:
>
> > -static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, gva_t gva,
> > +static hpa_t mmu_alloc_root(struct kvm_vcpu *vcpu, gfn_t gfn, int quadrant,
> > u8 level, bool direct)
> > {
> > + union kvm_mmu_page_role role;
> > struct kvm_mmu_page *sp;
> >
> > - sp = kvm_mmu_get_page(vcpu, gfn, gva, level, direct, ACC_ALL);
> > + role = vcpu->arch.mmu->root_role;
> > + role.level = level;
> > + role.direct = direct;
> > + role.access = ACC_ALL;
> > +
> > + if (role.has_4_byte_gpte)
> > + role.quadrant = quadrant;
> > +
> > + if (level <= vcpu->arch.mmu->cpu_role.base.level)
> > + role.passthrough = 0;
> > +
>
>
>
> + role.level = level;
> +
> + if (role.has_4_byte_gpte)
> + role.quadrant = quadrant;
>
> Only these lines are needed because of mmu->pae_root, others are
> the same as vcpu->arch.mmu->root_role.
>
> The argument @direct is vcpu->arch.mmu->root_role.direct.
> vcpu->arch.mmu->root_role.access is always set to be ACC_ALL.
>
> vcpu->arch.mmu->root_role.passthrough is 0 when mmu->pae_root is used.
> Or if vcpu->arch.mmu->root_role.passthrough is 1, @level must be 5
> and vcpu->arch.mmu->cpu_role.base.level must be 4, the code here
> is useless.
Ah, thank you for the tip. That is cleaner.
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
2022-05-16 3:31 ` Anup Patel
@ 2022-05-16 23:23 ` David Matlack
-1 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-16 23:23 UTC (permalink / raw)
To: Anup Patel
Cc: Paolo Bonzini, Marc Zyngier, Huacai Chen, Aleksandar Markovic,
Paul Walmsley, Palmer Dabbelt, Albert Ou, Sean Christopherson,
Andrew Jones, Ben Gardon, Peter Xu, Maciej S. Szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Peter Feiner, Lai Jiangshan
On Sun, May 15, 2022 at 8:32 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Sat, May 14, 2022 at 1:59 AM David Matlack <dmatlack@google.com> wrote:
> >
> > Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
> > declaration time rather than being fixed for all declarations. This will
> > be used in a follow-up commit to declare an cache in x86 with a capacity
> > of 512+ objects without having to increase the capacity of all caches in
> > KVM.
> >
> > This change requires each cache now specify its capacity at runtime,
> > since the cache struct itself no longer has a fixed capacity known at
> > compile time. To protect against someone accidentally defining a
> > kvm_mmu_memory_cache struct directly (without the extra storage), this
> > commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
> >
> > In order to support different capacities, this commit changes the
> > objects pointer array to be dynamically allocated the first time the
> > cache is topped-up.
> >
> > An alternative would be to lay out the objects array after the
> > kvm_mmu_memory_cache struct, which can be done at compile time. But that
> > change, unfortunately, adds some grottiness to arm64 and riscv, which
> > uses a function-local (i.e. stack-allocated) kvm_mmu_memory_cache
> > struct. Since C does not allow anonymous structs in functions, the new
> > wrapper struct that contains kvm_mmu_memory_cache and the objects
> > pointer array, must be named, which means dealing with an outer and
> > inner struct. The outer struct can't be dropped since then there would
> > be no guarantee the kvm_mmu_memory_cache struct and objects array would
> > be laid out consecutively on the stack.
> >
> > No functional change intended.
> >
> > Signed-off-by: David Matlack <dmatlack@google.com>
>
> Overall, this looks good to me. I wanted to try this patch with KVM RISC-V
> but there are conflicts in include/linux/kvm_types.h and virt/kvm/kvm_main.c
Hi Anup,
I just sent another version rebased on top of the latest kvm/queue.
Let me know if you are still seeing merge conflicts.
>
> Please take a look.
>
> Regards,
> Anup
>
> > ---
> > arch/arm64/kvm/arm.c | 1 +
> > arch/arm64/kvm/mmu.c | 5 ++++-
> > arch/mips/kvm/mips.c | 2 ++
> > arch/riscv/kvm/mmu.c | 8 ++++----
> > arch/riscv/kvm/vcpu.c | 1 +
> > arch/x86/kvm/mmu/mmu.c | 9 +++++++++
> > include/linux/kvm_types.h | 9 +++++++--
> > virt/kvm/kvm_main.c | 20 ++++++++++++++++++--
> > 8 files changed, 46 insertions(+), 9 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > index 7fceb855fa71..aa1e0c1659d4 100644
> > --- a/arch/arm64/kvm/arm.c
> > +++ b/arch/arm64/kvm/arm.c
> > @@ -320,6 +320,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> > vcpu->arch.target = -1;
> > bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
> >
> > + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
> >
> > /* Set up the timer */
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 53ae2c0640bc..2f2ef6b60ff4 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> > {
> > phys_addr_t addr;
> > int ret = 0;
> > - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> > + struct kvm_mmu_memory_cache cache = {
> > + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> > + .gfp_zero = __GFP_ZERO,
> > + };
> > struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> > enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> > KVM_PGTABLE_PROT_R |
> > diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> > index a25e0b73ee70..45c7179144dc 100644
> > --- a/arch/mips/kvm/mips.c
> > +++ b/arch/mips/kvm/mips.c
> > @@ -387,6 +387,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> > if (err)
> > goto out_free_gebase;
> >
> > + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > +
> > return 0;
> >
> > out_free_gebase:
> > diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> > index f80a34fbf102..8c2338ecc246 100644
> > --- a/arch/riscv/kvm/mmu.c
> > +++ b/arch/riscv/kvm/mmu.c
> > @@ -347,10 +347,10 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
> > int ret = 0;
> > unsigned long pfn;
> > phys_addr_t addr, end;
> > - struct kvm_mmu_memory_cache pcache;
> > -
> > - memset(&pcache, 0, sizeof(pcache));
> > - pcache.gfp_zero = __GFP_ZERO;
> > + struct kvm_mmu_memory_cache pcache = {
> > + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> > + .gfp_zero = __GFP_ZERO,
> > + };
> >
> > end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
> > pfn = __phys_to_pfn(hpa);
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 6785aef4cbd4..bbcb9d4a04fb 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -94,6 +94,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> >
> > /* Mark this VCPU never ran */
> > vcpu->arch.ran_atleast_once = false;
> > + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
> >
> > /* Setup ISA features available to VCPU */
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index 4b40fa2e27eb..dad7e19ef8ed 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -5803,12 +5803,21 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
> > {
> > int ret;
> >
> > + vcpu->arch.mmu_pte_list_desc_cache.capacity =
> > + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> > vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
> >
> > + vcpu->arch.mmu_page_header_cache.capacity =
> > + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> > vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
> >
> > + vcpu->arch.mmu_shadowed_info_cache.capacity =
> > + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > +
> > + vcpu->arch.mmu_shadow_page_cache.capacity =
> > + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
> >
> > vcpu->arch.mmu = &vcpu->arch.root_mmu;
> > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> > index ac1ebb37a0ff..549103a4f7bc 100644
> > --- a/include/linux/kvm_types.h
> > +++ b/include/linux/kvm_types.h
> > @@ -83,14 +83,19 @@ struct gfn_to_pfn_cache {
> > * MMU flows is problematic, as is triggering reclaim, I/O, etc... while
> > * holding MMU locks. Note, these caches act more like prefetch buffers than
> > * classical caches, i.e. objects are not returned to the cache on being freed.
> > + *
> > + * The storage for the cache object pointers is allocated dynamically when the
> > + * cache is topped-up. The capacity field defines the number of object pointers
> > + * available after the struct.
> > */
> > struct kvm_mmu_memory_cache {
> > int nobjs;
> > + int capacity;
> > gfp_t gfp_zero;
> > struct kmem_cache *kmem_cache;
> > - void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
> > + void **objects;
> > };
> > -#endif
> > +#endif /* KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE */
> >
> > #define HALT_POLL_HIST_COUNT 32
> >
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index e089db822c12..264e4107e06f 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -371,12 +371,23 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
> >
> > int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> > {
> > + gfp_t gfp = GFP_KERNEL_ACCOUNT;
> > void *obj;
> >
> > if (mc->nobjs >= min)
> > return 0;
> > - while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
> > - obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
> > +
> > + if (WARN_ON(mc->capacity == 0))
> > + return -EINVAL;
> > +
> > + if (!mc->objects) {
> > + mc->objects = kvmalloc_array(sizeof(void *), mc->capacity, gfp);
> > + if (!mc->objects)
> > + return -ENOMEM;
> > + }
> > +
> > + while (mc->nobjs < mc->capacity) {
> > + obj = mmu_memory_cache_alloc_obj(mc, gfp);
> > if (!obj)
> > return mc->nobjs >= min ? 0 : -ENOMEM;
> > mc->objects[mc->nobjs++] = obj;
> > @@ -397,6 +408,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> > else
> > free_page((unsigned long)mc->objects[--mc->nobjs]);
> > }
> > +
> > + kvfree(mc->objects);
> > +
> > + /* Note, must set to NULL to avoid use-after-free in the next top-up. */
> > + mc->objects = NULL;
> > }
> >
> > void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> > --
> > 2.36.0.550.gb090851708-goog
> >
^ permalink raw reply [flat|nested] 60+ messages in thread
* Re: [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs
@ 2022-05-16 23:23 ` David Matlack
0 siblings, 0 replies; 60+ messages in thread
From: David Matlack @ 2022-05-16 23:23 UTC (permalink / raw)
To: Anup Patel
Cc: Albert Ou, open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Marc Zyngier, Huacai Chen, Lai Jiangshan,
open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips),
Aleksandar Markovic, Palmer Dabbelt,
open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv),
Paul Walmsley, Ben Gardon, Paolo Bonzini, Maciej S. Szmigiero,
moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64),
Peter Feiner
On Sun, May 15, 2022 at 8:32 PM Anup Patel <anup@brainfault.org> wrote:
>
> On Sat, May 14, 2022 at 1:59 AM David Matlack <dmatlack@google.com> wrote:
> >
> > Allow the capacity of the kvm_mmu_memory_cache struct to be chosen at
> > declaration time rather than being fixed for all declarations. This will
> > be used in a follow-up commit to declare an cache in x86 with a capacity
> > of 512+ objects without having to increase the capacity of all caches in
> > KVM.
> >
> > This change requires each cache now specify its capacity at runtime,
> > since the cache struct itself no longer has a fixed capacity known at
> > compile time. To protect against someone accidentally defining a
> > kvm_mmu_memory_cache struct directly (without the extra storage), this
> > commit includes a WARN_ON() in kvm_mmu_topup_memory_cache().
> >
> > In order to support different capacities, this commit changes the
> > objects pointer array to be dynamically allocated the first time the
> > cache is topped-up.
> >
> > An alternative would be to lay out the objects array after the
> > kvm_mmu_memory_cache struct, which can be done at compile time. But that
> > change, unfortunately, adds some grottiness to arm64 and riscv, which
> > uses a function-local (i.e. stack-allocated) kvm_mmu_memory_cache
> > struct. Since C does not allow anonymous structs in functions, the new
> > wrapper struct that contains kvm_mmu_memory_cache and the objects
> > pointer array, must be named, which means dealing with an outer and
> > inner struct. The outer struct can't be dropped since then there would
> > be no guarantee the kvm_mmu_memory_cache struct and objects array would
> > be laid out consecutively on the stack.
> >
> > No functional change intended.
> >
> > Signed-off-by: David Matlack <dmatlack@google.com>
>
> Overall, this looks good to me. I wanted to try this patch with KVM RISC-V
> but there are conflicts in include/linux/kvm_types.h and virt/kvm/kvm_main.c
Hi Anup,
I just sent another version rebased on top of the latest kvm/queue.
Let me know if you are still seeing merge conflicts.
>
> Please take a look.
>
> Regards,
> Anup
>
> > ---
> > arch/arm64/kvm/arm.c | 1 +
> > arch/arm64/kvm/mmu.c | 5 ++++-
> > arch/mips/kvm/mips.c | 2 ++
> > arch/riscv/kvm/mmu.c | 8 ++++----
> > arch/riscv/kvm/vcpu.c | 1 +
> > arch/x86/kvm/mmu/mmu.c | 9 +++++++++
> > include/linux/kvm_types.h | 9 +++++++--
> > virt/kvm/kvm_main.c | 20 ++++++++++++++++++--
> > 8 files changed, 46 insertions(+), 9 deletions(-)
> >
> > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > index 7fceb855fa71..aa1e0c1659d4 100644
> > --- a/arch/arm64/kvm/arm.c
> > +++ b/arch/arm64/kvm/arm.c
> > @@ -320,6 +320,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> > vcpu->arch.target = -1;
> > bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
> >
> > + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
> >
> > /* Set up the timer */
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index 53ae2c0640bc..2f2ef6b60ff4 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -764,7 +764,10 @@ int kvm_phys_addr_ioremap(struct kvm *kvm, phys_addr_t guest_ipa,
> > {
> > phys_addr_t addr;
> > int ret = 0;
> > - struct kvm_mmu_memory_cache cache = { 0, __GFP_ZERO, NULL, };
> > + struct kvm_mmu_memory_cache cache = {
> > + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> > + .gfp_zero = __GFP_ZERO,
> > + };
> > struct kvm_pgtable *pgt = kvm->arch.mmu.pgt;
> > enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_DEVICE |
> > KVM_PGTABLE_PROT_R |
> > diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> > index a25e0b73ee70..45c7179144dc 100644
> > --- a/arch/mips/kvm/mips.c
> > +++ b/arch/mips/kvm/mips.c
> > @@ -387,6 +387,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> > if (err)
> > goto out_free_gebase;
> >
> > + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > +
> > return 0;
> >
> > out_free_gebase:
> > diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> > index f80a34fbf102..8c2338ecc246 100644
> > --- a/arch/riscv/kvm/mmu.c
> > +++ b/arch/riscv/kvm/mmu.c
> > @@ -347,10 +347,10 @@ static int stage2_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
> > int ret = 0;
> > unsigned long pfn;
> > phys_addr_t addr, end;
> > - struct kvm_mmu_memory_cache pcache;
> > -
> > - memset(&pcache, 0, sizeof(pcache));
> > - pcache.gfp_zero = __GFP_ZERO;
> > + struct kvm_mmu_memory_cache pcache = {
> > + .capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE,
> > + .gfp_zero = __GFP_ZERO,
> > + };
> >
> > end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
> > pfn = __phys_to_pfn(hpa);
> > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> > index 6785aef4cbd4..bbcb9d4a04fb 100644
> > --- a/arch/riscv/kvm/vcpu.c
> > +++ b/arch/riscv/kvm/vcpu.c
> > @@ -94,6 +94,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> >
> > /* Mark this VCPU never ran */
> > vcpu->arch.ran_atleast_once = false;
> > + vcpu->arch.mmu_page_cache.capacity = KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_page_cache.gfp_zero = __GFP_ZERO;
> >
> > /* Setup ISA features available to VCPU */
> > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
> > index 4b40fa2e27eb..dad7e19ef8ed 100644
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -5803,12 +5803,21 @@ int kvm_mmu_create(struct kvm_vcpu *vcpu)
> > {
> > int ret;
> >
> > + vcpu->arch.mmu_pte_list_desc_cache.capacity =
> > + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_pte_list_desc_cache.kmem_cache = pte_list_desc_cache;
> > vcpu->arch.mmu_pte_list_desc_cache.gfp_zero = __GFP_ZERO;
> >
> > + vcpu->arch.mmu_page_header_cache.capacity =
> > + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_page_header_cache.kmem_cache = mmu_page_header_cache;
> > vcpu->arch.mmu_page_header_cache.gfp_zero = __GFP_ZERO;
> >
> > + vcpu->arch.mmu_shadowed_info_cache.capacity =
> > + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > +
> > + vcpu->arch.mmu_shadow_page_cache.capacity =
> > + KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE;
> > vcpu->arch.mmu_shadow_page_cache.gfp_zero = __GFP_ZERO;
> >
> > vcpu->arch.mmu = &vcpu->arch.root_mmu;
> > diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
> > index ac1ebb37a0ff..549103a4f7bc 100644
> > --- a/include/linux/kvm_types.h
> > +++ b/include/linux/kvm_types.h
> > @@ -83,14 +83,19 @@ struct gfn_to_pfn_cache {
> > * MMU flows is problematic, as is triggering reclaim, I/O, etc... while
> > * holding MMU locks. Note, these caches act more like prefetch buffers than
> > * classical caches, i.e. objects are not returned to the cache on being freed.
> > + *
> > + * The storage for the cache object pointers is allocated dynamically when the
> > + * cache is topped-up. The capacity field defines the number of object pointers
> > + * available after the struct.
> > */
> > struct kvm_mmu_memory_cache {
> > int nobjs;
> > + int capacity;
> > gfp_t gfp_zero;
> > struct kmem_cache *kmem_cache;
> > - void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
> > + void **objects;
> > };
> > -#endif
> > +#endif /* KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE */
> >
> > #define HALT_POLL_HIST_COUNT 32
> >
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index e089db822c12..264e4107e06f 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -371,12 +371,23 @@ static inline void *mmu_memory_cache_alloc_obj(struct kvm_mmu_memory_cache *mc,
> >
> > int kvm_mmu_topup_memory_cache(struct kvm_mmu_memory_cache *mc, int min)
> > {
> > + gfp_t gfp = GFP_KERNEL_ACCOUNT;
> > void *obj;
> >
> > if (mc->nobjs >= min)
> > return 0;
> > - while (mc->nobjs < ARRAY_SIZE(mc->objects)) {
> > - obj = mmu_memory_cache_alloc_obj(mc, GFP_KERNEL_ACCOUNT);
> > +
> > + if (WARN_ON(mc->capacity == 0))
> > + return -EINVAL;
> > +
> > + if (!mc->objects) {
> > + mc->objects = kvmalloc_array(sizeof(void *), mc->capacity, gfp);
> > + if (!mc->objects)
> > + return -ENOMEM;
> > + }
> > +
> > + while (mc->nobjs < mc->capacity) {
> > + obj = mmu_memory_cache_alloc_obj(mc, gfp);
> > if (!obj)
> > return mc->nobjs >= min ? 0 : -ENOMEM;
> > mc->objects[mc->nobjs++] = obj;
> > @@ -397,6 +408,11 @@ void kvm_mmu_free_memory_cache(struct kvm_mmu_memory_cache *mc)
> > else
> > free_page((unsigned long)mc->objects[--mc->nobjs]);
> > }
> > +
> > + kvfree(mc->objects);
> > +
> > + /* Note, must set to NULL to avoid use-after-free in the next top-up. */
> > + mc->objects = NULL;
> > }
> >
> > void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc)
> > --
> > 2.36.0.550.gb090851708-goog
> >
_______________________________________________
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kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 60+ messages in thread
end of thread, other threads:[~2022-05-17 7:02 UTC | newest]
Thread overview: 60+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-13 20:27 [PATCH v5 00/21] KVM: Extend Eager Page Splitting to the shadow MMU David Matlack
2022-05-13 20:27 ` David Matlack
2022-05-13 20:27 ` [PATCH v5 01/21] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs David Matlack
2022-05-13 20:27 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 02/21] KVM: x86/mmu: Use a bool for direct David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 03/21] KVM: x86/mmu: Derive shadow MMU page role from parent David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-16 6:54 ` Lai Jiangshan
2022-05-16 6:54 ` Lai Jiangshan
2022-05-16 21:38 ` David Matlack
2022-05-16 21:38 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 04/21] KVM: x86/mmu: Always pass 0 for @quadrant when gptes are 8 bytes David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 05/21] KVM: x86/mmu: Decompose kvm_mmu_get_page() into separate functions David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 06/21] KVM: x86/mmu: Consolidate shadow page allocation and initialization David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 07/21] KVM: x86/mmu: Rename shadow MMU functions that deal with shadow pages David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 08/21] KVM: x86/mmu: Move guest PT write-protection to account_shadowed() David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 09/21] KVM: x86/mmu: Pass memory caches to allocate SPs separately David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 10/21] KVM: x86/mmu: Replace vcpu with kvm in kvm_mmu_alloc_shadow_page() David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 11/21] KVM: x86/mmu: Pass kvm pointer separately from vcpu to kvm_mmu_find_shadow_page() David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 12/21] KVM: x86/mmu: Allow NULL @vcpu in kvm_mmu_find_shadow_page() David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 13/21] KVM: x86/mmu: Pass const memslot to rmap_add() David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 14/21] KVM: x86/mmu: Decouple rmap_add() and link_shadow_page() from kvm_vcpu David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 15/21] KVM: x86/mmu: Update page stats in __rmap_add() David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 16/21] KVM: x86/mmu: Cache the access bits of shadowed translations David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 17/21] KVM: x86/mmu: Extend make_huge_page_split_spte() for the shadow MMU David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 18/21] KVM: x86/mmu: Zap collapsible SPTEs in shadow MMU at all possible levels David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 19/21] KVM: x86/mmu: Refactor drop_large_spte() David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-13 20:28 ` [PATCH v5 20/21] KVM: Allow for different capacities in kvm_mmu_memory_cache structs David Matlack
2022-05-13 20:28 ` David Matlack
2022-05-15 11:42 ` Marc Zyngier
2022-05-15 11:42 ` Marc Zyngier
2022-05-16 3:31 ` Anup Patel
2022-05-16 3:31 ` Anup Patel
2022-05-16 23:23 ` David Matlack
2022-05-16 23:23 ` David Matlack
2022-05-16 14:49 ` Sean Christopherson
2022-05-16 14:49 ` Sean Christopherson
2022-05-16 16:39 ` David Matlack
2022-05-16 16:39 ` David Matlack
2022-05-16 17:53 ` Sean Christopherson
2022-05-16 17:53 ` Sean Christopherson
2022-05-13 20:28 ` [PATCH v5 21/21] KVM: x86/mmu: Extend Eager Page Splitting to nested MMUs David Matlack
2022-05-13 20:28 ` David Matlack
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