* [RFC 0/6] KVM: arm64: implement vcpu_is_preempted check
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
This patchset adds support for vcpu_is_preempted in arm64, which allows the guest
to check if a vcpu was scheduled out, which is useful to know incase it was
holding a lock. vcpu_is_preempted can be used to improve
performance in locking (see owner_on_cpu usage in mutex_spin_on_owner,
mutex_can_spin_on_owner, rtmutex_spin_on_owner and osq_lock) and scheduling
(see available_idle_cpu which is used in several places in kernel/sched/fair.c
for e.g. in wake_affine to determine which CPU can run soonest):
This patchset shows improvement on overcommitted hosts (vCPUs > pCPUS), as waiting
for preempted vCPUs reduces performance.
This patchset is inspired from the para_steal_clock implementation and from the
work originally done by Zengruan Ye:
https://lore.kernel.org/linux-arm-kernel/20191226135833.1052-1-yezengruan@huawei.com/.
(I have kept the original file author and patch sign-offs, hope thats ok).
All the results in the below experiments are done on an aws r6g.metal instance
which has 64 pCPUs.
The following table shows the index results of UnixBench running on a 128 vCPU VM
with (6.0.0+vcpu_is_preempted) and without (6.0.0 base) the patchset.
TestName 6.0.0 base 6.0.0+vcpu_is_preempted % improvement for vcpu_is_preempted
Dhrystone 2 using register variables 187761 191274.7 1.871368389
Double-Precision Whetstone 96743.6 98414.4 1.727039308
Execl Throughput 689.3 10426 1412.548963
File Copy 1024 bufsize 2000 maxblocks 549.5 3165 475.978162
File Copy 256 bufsize 500 maxblocks 400.7 2084.7 420.2645371
File Copy 4096 bufsize 8000 maxblocks 894.3 5003.2 459.4543218
Pipe Throughput 76819.5 78601.5 2.319723508
Pipe-based Context Switching 3444.8 13414.5 289.4130283
Process Creation 301.1 293.4 -2.557289937
Shell Scripts (1 concurrent) 1248.1 28300.6 2167.494592
Shell Scripts (8 concurrent) 781.2 26222.3 3256.669227
System Call Overhead 3426 3729.4 8.855808523
System Benchmarks Index Score 3053 11534 277.7923354
This shows a 277% overall improvement using these patches.
The biggest improvement is in the shell scripts benchmark, which forks a lot of processes.
This acquires rwsem lock where a large chunk of time is spent in base 6.0.0 kernel.
This can be seen from one of the callstack of the perf output of the shell
scripts benchmark on 6.0.0 base (pseudo NMI enabled for perf numbers below):
- 33.79% el0_svc
- 33.43% do_el0_svc
- 33.43% el0_svc_common.constprop.3
- 33.30% invoke_syscall
- 17.27% __arm64_sys_clone
- 17.27% __do_sys_clone
- 17.26% kernel_clone
- 16.73% copy_process
- 11.91% dup_mm
- 11.82% dup_mmap
- 9.15% down_write
- 8.87% rwsem_down_write_slowpath
- 8.48% osq_lock
Just under 50% of the total time in the shell script benchmarks ends up being
spent in osq_lock in the base 6.0.0 kernel:
Children Self Command Shared Object Symbol
17.19% 10.71% sh [kernel.kallsyms] [k] osq_lock
6.17% 4.04% sort [kernel.kallsyms] [k] osq_lock
4.20% 2.60% multi. [kernel.kallsyms] [k] osq_lock
3.77% 2.47% grep [kernel.kallsyms] [k] osq_lock
3.50% 2.24% expr [kernel.kallsyms] [k] osq_lock
3.41% 2.23% od [kernel.kallsyms] [k] osq_lock
3.36% 2.15% rm [kernel.kallsyms] [k] osq_lock
3.28% 2.12% tee [kernel.kallsyms] [k] osq_lock
3.16% 2.02% wc [kernel.kallsyms] [k] osq_lock
0.21% 0.13% looper [kernel.kallsyms] [k] osq_lock
0.01% 0.00% Run [kernel.kallsyms] [k] osq_lock
and this comes down to less than 1% total with 6.0.0+vcpu_is_preempted kernel:
Children Self Command Shared Object Symbol
0.26% 0.21% sh [kernel.kallsyms] [k] osq_lock
0.10% 0.08% multi. [kernel.kallsyms] [k] osq_lock
0.04% 0.04% sort [kernel.kallsyms] [k] osq_lock
0.02% 0.01% grep [kernel.kallsyms] [k] osq_lock
0.02% 0.02% od [kernel.kallsyms] [k] osq_lock
0.01% 0.01% tee [kernel.kallsyms] [k] osq_lock
0.01% 0.00% expr [kernel.kallsyms] [k] osq_lock
0.01% 0.01% looper [kernel.kallsyms] [k] osq_lock
0.00% 0.00% wc [kernel.kallsyms] [k] osq_lock
0.00% 0.00% rm [kernel.kallsyms] [k] osq_lock
To make sure, there is no change in performance when vCPUs < pCPUs, UnixBench
was run on a 32 CPU VM. The kernel with vcpu_is_preempted implemented
performed 0.9% better overall than base kernel, and the individual benchmarks
were within +/-2% improvement over 6.0.0 base.
Hence the patches have no negative affect when vCPUs < pCPUs.
The other method discussed in https://lore.kernel.org/linux-arm-kernel/20191226135833.1052-1-yezengruan@huawei.com/
was pv conditional yield by Marc Zyngier and Will Deacon to reduce vCPU reschedule
if the vCPU will exit immediately.
(https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/pvcy).
The patches were ported to 6.0.0 kernel and tested with UnixBench with a 128 vCPU VM:
TestName 6.0.0 base 6.0.0+pvcy % improvement for pvcy
Dhrystone 2 using register variables 187761 183128 -2.467498575
Double-Precision Whetstone 96743.6 96645 -0.101918887
Execl Throughput 689.3 1019.8 47.9471928
File Copy 1024 bufsize 2000 maxblocks 549.5 2029.7 269.3721565
File Copy 256 bufsize 500 maxblocks 400.7 1439.4 259.2213626
File Copy 4096 bufsize 8000 maxblocks 894.3 3434.1 283.9986582
Pipe Throughput 76819.5 74268.8 -3.320380893
Pipe-based Context Switching 3444.8 5963.3 73.11019508
Process Creation 301.1 163.2 -45.79873796
Shell Scripts (1 concurrent) 1248.1 1859.7 49.00248378
Shell Scripts (8 concurrent) 781.2 1171 49.89759345
System Call Overhead 3426 3194.4 -6.760070053
System Benchmarks Index Score 3053 4605 50.83524402
pvcy shows a smaller overall improvement (50%) compared to vcpu_is_preempted (277%).
Host side flamegraph analysis shows that ~60% of the host time when using pvcy
is spent in kvm_handle_wfx, compared with ~1.5% when using vcpu_is_preempted,
hence vcpu_is_preempted shows a larger improvement.
It might be that pvcy can be used in combination with vcpu_is_preempted, but this
series is to start a discussion on vcpu_is_preempted as it shows a much bigger
improvement in performance and its much easier to review vcpu_is_preempted standalone.
The respective QEMU change to test this is at
https://github.com/uarif1/qemu/commit/2da2c2927ae8de8f03f439804a0dad9cf68501b6,
if this patchset looks good to start review, I can send the QEMU change to the
qemu mailing list to start its review as well.
Looking forward to your response!
Thanks,
Usama
Usama Arif (6):
KVM: arm64: Document PV-lock interface
KVM: arm64: Add SMCCC paravirtualised lock calls
KVM: arm64: Support pvlock preempted via shared structure
KVM: arm64: Provide VCPU attributes for PV lock
KVM: arm64: Support the VCPU preemption check
KVM: selftests: add tests for PV time specific hypercalls
Documentation/virt/kvm/arm/hypercalls.rst | 3 +
Documentation/virt/kvm/arm/pvlock.rst | 64 +++++++++
Documentation/virt/kvm/devices/vcpu.rst | 23 ++++
arch/arm64/include/asm/kvm_host.h | 25 ++++
arch/arm64/include/asm/paravirt.h | 2 +
arch/arm64/include/asm/pvlock-abi.h | 17 +++
arch/arm64/include/asm/spinlock.h | 16 ++-
arch/arm64/include/uapi/asm/kvm.h | 3 +
arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++
arch/arm64/kernel/setup.c | 3 +
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arm.c | 8 ++
arch/arm64/kvm/guest.c | 9 ++
arch/arm64/kvm/hypercalls.c | 36 +++++
arch/arm64/kvm/pvlock.c | 100 ++++++++++++++
arch/arm64/kvm/pvtime.c | 16 ---
include/linux/arm-smccc.h | 13 ++
include/linux/cpuhotplug.h | 1 +
include/uapi/linux/kvm.h | 2 +
tools/arch/arm64/include/uapi/asm/kvm.h | 1 +
tools/include/linux/arm-smccc.h | 13 ++
.../selftests/kvm/aarch64/hypercalls.c | 2 +
22 files changed, 467 insertions(+), 18 deletions(-)
create mode 100644 Documentation/virt/kvm/arm/pvlock.rst
create mode 100644 arch/arm64/include/asm/pvlock-abi.h
create mode 100644 arch/arm64/kvm/pvlock.c
--
2.25.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 36+ messages in thread
* [RFC 0/6] KVM: arm64: implement vcpu_is_preempted check
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
This patchset adds support for vcpu_is_preempted in arm64, which allows the guest
to check if a vcpu was scheduled out, which is useful to know incase it was
holding a lock. vcpu_is_preempted can be used to improve
performance in locking (see owner_on_cpu usage in mutex_spin_on_owner,
mutex_can_spin_on_owner, rtmutex_spin_on_owner and osq_lock) and scheduling
(see available_idle_cpu which is used in several places in kernel/sched/fair.c
for e.g. in wake_affine to determine which CPU can run soonest):
This patchset shows improvement on overcommitted hosts (vCPUs > pCPUS), as waiting
for preempted vCPUs reduces performance.
This patchset is inspired from the para_steal_clock implementation and from the
work originally done by Zengruan Ye:
https://lore.kernel.org/linux-arm-kernel/20191226135833.1052-1-yezengruan@huawei.com/.
(I have kept the original file author and patch sign-offs, hope thats ok).
All the results in the below experiments are done on an aws r6g.metal instance
which has 64 pCPUs.
The following table shows the index results of UnixBench running on a 128 vCPU VM
with (6.0.0+vcpu_is_preempted) and without (6.0.0 base) the patchset.
TestName 6.0.0 base 6.0.0+vcpu_is_preempted % improvement for vcpu_is_preempted
Dhrystone 2 using register variables 187761 191274.7 1.871368389
Double-Precision Whetstone 96743.6 98414.4 1.727039308
Execl Throughput 689.3 10426 1412.548963
File Copy 1024 bufsize 2000 maxblocks 549.5 3165 475.978162
File Copy 256 bufsize 500 maxblocks 400.7 2084.7 420.2645371
File Copy 4096 bufsize 8000 maxblocks 894.3 5003.2 459.4543218
Pipe Throughput 76819.5 78601.5 2.319723508
Pipe-based Context Switching 3444.8 13414.5 289.4130283
Process Creation 301.1 293.4 -2.557289937
Shell Scripts (1 concurrent) 1248.1 28300.6 2167.494592
Shell Scripts (8 concurrent) 781.2 26222.3 3256.669227
System Call Overhead 3426 3729.4 8.855808523
System Benchmarks Index Score 3053 11534 277.7923354
This shows a 277% overall improvement using these patches.
The biggest improvement is in the shell scripts benchmark, which forks a lot of processes.
This acquires rwsem lock where a large chunk of time is spent in base 6.0.0 kernel.
This can be seen from one of the callstack of the perf output of the shell
scripts benchmark on 6.0.0 base (pseudo NMI enabled for perf numbers below):
- 33.79% el0_svc
- 33.43% do_el0_svc
- 33.43% el0_svc_common.constprop.3
- 33.30% invoke_syscall
- 17.27% __arm64_sys_clone
- 17.27% __do_sys_clone
- 17.26% kernel_clone
- 16.73% copy_process
- 11.91% dup_mm
- 11.82% dup_mmap
- 9.15% down_write
- 8.87% rwsem_down_write_slowpath
- 8.48% osq_lock
Just under 50% of the total time in the shell script benchmarks ends up being
spent in osq_lock in the base 6.0.0 kernel:
Children Self Command Shared Object Symbol
17.19% 10.71% sh [kernel.kallsyms] [k] osq_lock
6.17% 4.04% sort [kernel.kallsyms] [k] osq_lock
4.20% 2.60% multi. [kernel.kallsyms] [k] osq_lock
3.77% 2.47% grep [kernel.kallsyms] [k] osq_lock
3.50% 2.24% expr [kernel.kallsyms] [k] osq_lock
3.41% 2.23% od [kernel.kallsyms] [k] osq_lock
3.36% 2.15% rm [kernel.kallsyms] [k] osq_lock
3.28% 2.12% tee [kernel.kallsyms] [k] osq_lock
3.16% 2.02% wc [kernel.kallsyms] [k] osq_lock
0.21% 0.13% looper [kernel.kallsyms] [k] osq_lock
0.01% 0.00% Run [kernel.kallsyms] [k] osq_lock
and this comes down to less than 1% total with 6.0.0+vcpu_is_preempted kernel:
Children Self Command Shared Object Symbol
0.26% 0.21% sh [kernel.kallsyms] [k] osq_lock
0.10% 0.08% multi. [kernel.kallsyms] [k] osq_lock
0.04% 0.04% sort [kernel.kallsyms] [k] osq_lock
0.02% 0.01% grep [kernel.kallsyms] [k] osq_lock
0.02% 0.02% od [kernel.kallsyms] [k] osq_lock
0.01% 0.01% tee [kernel.kallsyms] [k] osq_lock
0.01% 0.00% expr [kernel.kallsyms] [k] osq_lock
0.01% 0.01% looper [kernel.kallsyms] [k] osq_lock
0.00% 0.00% wc [kernel.kallsyms] [k] osq_lock
0.00% 0.00% rm [kernel.kallsyms] [k] osq_lock
To make sure, there is no change in performance when vCPUs < pCPUs, UnixBench
was run on a 32 CPU VM. The kernel with vcpu_is_preempted implemented
performed 0.9% better overall than base kernel, and the individual benchmarks
were within +/-2% improvement over 6.0.0 base.
Hence the patches have no negative affect when vCPUs < pCPUs.
The other method discussed in https://lore.kernel.org/linux-arm-kernel/20191226135833.1052-1-yezengruan@huawei.com/
was pv conditional yield by Marc Zyngier and Will Deacon to reduce vCPU reschedule
if the vCPU will exit immediately.
(https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/pvcy).
The patches were ported to 6.0.0 kernel and tested with UnixBench with a 128 vCPU VM:
TestName 6.0.0 base 6.0.0+pvcy % improvement for pvcy
Dhrystone 2 using register variables 187761 183128 -2.467498575
Double-Precision Whetstone 96743.6 96645 -0.101918887
Execl Throughput 689.3 1019.8 47.9471928
File Copy 1024 bufsize 2000 maxblocks 549.5 2029.7 269.3721565
File Copy 256 bufsize 500 maxblocks 400.7 1439.4 259.2213626
File Copy 4096 bufsize 8000 maxblocks 894.3 3434.1 283.9986582
Pipe Throughput 76819.5 74268.8 -3.320380893
Pipe-based Context Switching 3444.8 5963.3 73.11019508
Process Creation 301.1 163.2 -45.79873796
Shell Scripts (1 concurrent) 1248.1 1859.7 49.00248378
Shell Scripts (8 concurrent) 781.2 1171 49.89759345
System Call Overhead 3426 3194.4 -6.760070053
System Benchmarks Index Score 3053 4605 50.83524402
pvcy shows a smaller overall improvement (50%) compared to vcpu_is_preempted (277%).
Host side flamegraph analysis shows that ~60% of the host time when using pvcy
is spent in kvm_handle_wfx, compared with ~1.5% when using vcpu_is_preempted,
hence vcpu_is_preempted shows a larger improvement.
It might be that pvcy can be used in combination with vcpu_is_preempted, but this
series is to start a discussion on vcpu_is_preempted as it shows a much bigger
improvement in performance and its much easier to review vcpu_is_preempted standalone.
The respective QEMU change to test this is at
https://github.com/uarif1/qemu/commit/2da2c2927ae8de8f03f439804a0dad9cf68501b6,
if this patchset looks good to start review, I can send the QEMU change to the
qemu mailing list to start its review as well.
Looking forward to your response!
Thanks,
Usama
Usama Arif (6):
KVM: arm64: Document PV-lock interface
KVM: arm64: Add SMCCC paravirtualised lock calls
KVM: arm64: Support pvlock preempted via shared structure
KVM: arm64: Provide VCPU attributes for PV lock
KVM: arm64: Support the VCPU preemption check
KVM: selftests: add tests for PV time specific hypercalls
Documentation/virt/kvm/arm/hypercalls.rst | 3 +
Documentation/virt/kvm/arm/pvlock.rst | 64 +++++++++
Documentation/virt/kvm/devices/vcpu.rst | 23 ++++
arch/arm64/include/asm/kvm_host.h | 25 ++++
arch/arm64/include/asm/paravirt.h | 2 +
arch/arm64/include/asm/pvlock-abi.h | 17 +++
arch/arm64/include/asm/spinlock.h | 16 ++-
arch/arm64/include/uapi/asm/kvm.h | 3 +
arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++
arch/arm64/kernel/setup.c | 3 +
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arm.c | 8 ++
arch/arm64/kvm/guest.c | 9 ++
arch/arm64/kvm/hypercalls.c | 36 +++++
arch/arm64/kvm/pvlock.c | 100 ++++++++++++++
arch/arm64/kvm/pvtime.c | 16 ---
include/linux/arm-smccc.h | 13 ++
include/linux/cpuhotplug.h | 1 +
include/uapi/linux/kvm.h | 2 +
tools/arch/arm64/include/uapi/asm/kvm.h | 1 +
tools/include/linux/arm-smccc.h | 13 ++
.../selftests/kvm/aarch64/hypercalls.c | 2 +
22 files changed, 467 insertions(+), 18 deletions(-)
create mode 100644 Documentation/virt/kvm/arm/pvlock.rst
create mode 100644 arch/arm64/include/asm/pvlock-abi.h
create mode 100644 arch/arm64/kvm/pvlock.c
--
2.25.1
^ permalink raw reply [flat|nested] 36+ messages in thread
* [RFC 0/6] KVM: arm64: implement vcpu_is_preempted check
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma, Usama Arif
This patchset adds support for vcpu_is_preempted in arm64, which allows the guest
to check if a vcpu was scheduled out, which is useful to know incase it was
holding a lock. vcpu_is_preempted can be used to improve
performance in locking (see owner_on_cpu usage in mutex_spin_on_owner,
mutex_can_spin_on_owner, rtmutex_spin_on_owner and osq_lock) and scheduling
(see available_idle_cpu which is used in several places in kernel/sched/fair.c
for e.g. in wake_affine to determine which CPU can run soonest):
This patchset shows improvement on overcommitted hosts (vCPUs > pCPUS), as waiting
for preempted vCPUs reduces performance.
This patchset is inspired from the para_steal_clock implementation and from the
work originally done by Zengruan Ye:
https://lore.kernel.org/linux-arm-kernel/20191226135833.1052-1-yezengruan@huawei.com/.
(I have kept the original file author and patch sign-offs, hope thats ok).
All the results in the below experiments are done on an aws r6g.metal instance
which has 64 pCPUs.
The following table shows the index results of UnixBench running on a 128 vCPU VM
with (6.0.0+vcpu_is_preempted) and without (6.0.0 base) the patchset.
TestName 6.0.0 base 6.0.0+vcpu_is_preempted % improvement for vcpu_is_preempted
Dhrystone 2 using register variables 187761 191274.7 1.871368389
Double-Precision Whetstone 96743.6 98414.4 1.727039308
Execl Throughput 689.3 10426 1412.548963
File Copy 1024 bufsize 2000 maxblocks 549.5 3165 475.978162
File Copy 256 bufsize 500 maxblocks 400.7 2084.7 420.2645371
File Copy 4096 bufsize 8000 maxblocks 894.3 5003.2 459.4543218
Pipe Throughput 76819.5 78601.5 2.319723508
Pipe-based Context Switching 3444.8 13414.5 289.4130283
Process Creation 301.1 293.4 -2.557289937
Shell Scripts (1 concurrent) 1248.1 28300.6 2167.494592
Shell Scripts (8 concurrent) 781.2 26222.3 3256.669227
System Call Overhead 3426 3729.4 8.855808523
System Benchmarks Index Score 3053 11534 277.7923354
This shows a 277% overall improvement using these patches.
The biggest improvement is in the shell scripts benchmark, which forks a lot of processes.
This acquires rwsem lock where a large chunk of time is spent in base 6.0.0 kernel.
This can be seen from one of the callstack of the perf output of the shell
scripts benchmark on 6.0.0 base (pseudo NMI enabled for perf numbers below):
- 33.79% el0_svc
- 33.43% do_el0_svc
- 33.43% el0_svc_common.constprop.3
- 33.30% invoke_syscall
- 17.27% __arm64_sys_clone
- 17.27% __do_sys_clone
- 17.26% kernel_clone
- 16.73% copy_process
- 11.91% dup_mm
- 11.82% dup_mmap
- 9.15% down_write
- 8.87% rwsem_down_write_slowpath
- 8.48% osq_lock
Just under 50% of the total time in the shell script benchmarks ends up being
spent in osq_lock in the base 6.0.0 kernel:
Children Self Command Shared Object Symbol
17.19% 10.71% sh [kernel.kallsyms] [k] osq_lock
6.17% 4.04% sort [kernel.kallsyms] [k] osq_lock
4.20% 2.60% multi. [kernel.kallsyms] [k] osq_lock
3.77% 2.47% grep [kernel.kallsyms] [k] osq_lock
3.50% 2.24% expr [kernel.kallsyms] [k] osq_lock
3.41% 2.23% od [kernel.kallsyms] [k] osq_lock
3.36% 2.15% rm [kernel.kallsyms] [k] osq_lock
3.28% 2.12% tee [kernel.kallsyms] [k] osq_lock
3.16% 2.02% wc [kernel.kallsyms] [k] osq_lock
0.21% 0.13% looper [kernel.kallsyms] [k] osq_lock
0.01% 0.00% Run [kernel.kallsyms] [k] osq_lock
and this comes down to less than 1% total with 6.0.0+vcpu_is_preempted kernel:
Children Self Command Shared Object Symbol
0.26% 0.21% sh [kernel.kallsyms] [k] osq_lock
0.10% 0.08% multi. [kernel.kallsyms] [k] osq_lock
0.04% 0.04% sort [kernel.kallsyms] [k] osq_lock
0.02% 0.01% grep [kernel.kallsyms] [k] osq_lock
0.02% 0.02% od [kernel.kallsyms] [k] osq_lock
0.01% 0.01% tee [kernel.kallsyms] [k] osq_lock
0.01% 0.00% expr [kernel.kallsyms] [k] osq_lock
0.01% 0.01% looper [kernel.kallsyms] [k] osq_lock
0.00% 0.00% wc [kernel.kallsyms] [k] osq_lock
0.00% 0.00% rm [kernel.kallsyms] [k] osq_lock
To make sure, there is no change in performance when vCPUs < pCPUs, UnixBench
was run on a 32 CPU VM. The kernel with vcpu_is_preempted implemented
performed 0.9% better overall than base kernel, and the individual benchmarks
were within +/-2% improvement over 6.0.0 base.
Hence the patches have no negative affect when vCPUs < pCPUs.
The other method discussed in https://lore.kernel.org/linux-arm-kernel/20191226135833.1052-1-yezengruan@huawei.com/
was pv conditional yield by Marc Zyngier and Will Deacon to reduce vCPU reschedule
if the vCPU will exit immediately.
(https://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git/log/?h=kvm-arm64/pvcy).
The patches were ported to 6.0.0 kernel and tested with UnixBench with a 128 vCPU VM:
TestName 6.0.0 base 6.0.0+pvcy % improvement for pvcy
Dhrystone 2 using register variables 187761 183128 -2.467498575
Double-Precision Whetstone 96743.6 96645 -0.101918887
Execl Throughput 689.3 1019.8 47.9471928
File Copy 1024 bufsize 2000 maxblocks 549.5 2029.7 269.3721565
File Copy 256 bufsize 500 maxblocks 400.7 1439.4 259.2213626
File Copy 4096 bufsize 8000 maxblocks 894.3 3434.1 283.9986582
Pipe Throughput 76819.5 74268.8 -3.320380893
Pipe-based Context Switching 3444.8 5963.3 73.11019508
Process Creation 301.1 163.2 -45.79873796
Shell Scripts (1 concurrent) 1248.1 1859.7 49.00248378
Shell Scripts (8 concurrent) 781.2 1171 49.89759345
System Call Overhead 3426 3194.4 -6.760070053
System Benchmarks Index Score 3053 4605 50.83524402
pvcy shows a smaller overall improvement (50%) compared to vcpu_is_preempted (277%).
Host side flamegraph analysis shows that ~60% of the host time when using pvcy
is spent in kvm_handle_wfx, compared with ~1.5% when using vcpu_is_preempted,
hence vcpu_is_preempted shows a larger improvement.
It might be that pvcy can be used in combination with vcpu_is_preempted, but this
series is to start a discussion on vcpu_is_preempted as it shows a much bigger
improvement in performance and its much easier to review vcpu_is_preempted standalone.
The respective QEMU change to test this is at
https://github.com/uarif1/qemu/commit/2da2c2927ae8de8f03f439804a0dad9cf68501b6,
if this patchset looks good to start review, I can send the QEMU change to the
qemu mailing list to start its review as well.
Looking forward to your response!
Thanks,
Usama
Usama Arif (6):
KVM: arm64: Document PV-lock interface
KVM: arm64: Add SMCCC paravirtualised lock calls
KVM: arm64: Support pvlock preempted via shared structure
KVM: arm64: Provide VCPU attributes for PV lock
KVM: arm64: Support the VCPU preemption check
KVM: selftests: add tests for PV time specific hypercalls
Documentation/virt/kvm/arm/hypercalls.rst | 3 +
Documentation/virt/kvm/arm/pvlock.rst | 64 +++++++++
Documentation/virt/kvm/devices/vcpu.rst | 23 ++++
arch/arm64/include/asm/kvm_host.h | 25 ++++
arch/arm64/include/asm/paravirt.h | 2 +
arch/arm64/include/asm/pvlock-abi.h | 17 +++
arch/arm64/include/asm/spinlock.h | 16 ++-
arch/arm64/include/uapi/asm/kvm.h | 3 +
arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++
arch/arm64/kernel/setup.c | 3 +
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arm.c | 8 ++
arch/arm64/kvm/guest.c | 9 ++
arch/arm64/kvm/hypercalls.c | 36 +++++
arch/arm64/kvm/pvlock.c | 100 ++++++++++++++
arch/arm64/kvm/pvtime.c | 16 ---
include/linux/arm-smccc.h | 13 ++
include/linux/cpuhotplug.h | 1 +
include/uapi/linux/kvm.h | 2 +
tools/arch/arm64/include/uapi/asm/kvm.h | 1 +
tools/include/linux/arm-smccc.h | 13 ++
.../selftests/kvm/aarch64/hypercalls.c | 2 +
22 files changed, 467 insertions(+), 18 deletions(-)
create mode 100644 Documentation/virt/kvm/arm/pvlock.rst
create mode 100644 arch/arm64/include/asm/pvlock-abi.h
create mode 100644 arch/arm64/kvm/pvlock.c
--
2.25.1
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 36+ messages in thread
* [RFC 1/6] KVM: arm64: Document PV-lock interface
2022-11-02 16:13 ` Usama Arif
(?)
@ 2022-11-02 16:13 ` Usama Arif
-1 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Introduce a paravirtualization interface for KVM/arm64 to obtain whether
the VCPU is currently running or not.
The PV lock structure of the guest is allocated by user space.
A hypercall interface is provided for the guest to interrogate the
hypervisor's support for this interface and the location of the shared
memory structures.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
Documentation/virt/kvm/arm/pvlock.rst | 64 +++++++++++++++++++++++++
Documentation/virt/kvm/devices/vcpu.rst | 23 +++++++++
2 files changed, 87 insertions(+)
create mode 100644 Documentation/virt/kvm/arm/pvlock.rst
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
new file mode 100644
index 000000000000..766aeef50b2d
--- /dev/null
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -0,0 +1,64 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Paravirtualized lock support for arm64
+======================================
+
+KVM/arm64 provides hypervisor service calls for paravirtualized guests to check
+whether a VCPU is currently running or not.
+
+Two new SMCCC compatible hypercalls are defined:
+
+* PV_LOCK_FEATURES: 0xC6000020
+* PV_LOCK_PREEMPTED: 0xC6000021
+
+The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
+ARCH_FEATURES mechanism before calling it.
+
+PV_LOCK_FEATURES
+ ============= ======== ==========
+ Function ID: (uint32) 0xC6000020
+ PV_call_id: (uint32) The function to query for support.
+ Currently only PV_LOCK_PREEMPTED is supported.
+ Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
+ PV-lock feature is supported by the hypervisor.
+ ============= ======== ==========
+
+PV_LOCK_PREEMPTED
+ ============= ======== ==========
+ Function ID: (uint32) 0xC6000021
+ Return value: (int64) IPA of the pv lock data structure for this
+ VCPU. On failure:
+ NOT_SUPPORTED (-1)
+ ============= ======== ==========
+
+The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
+memory with inner and outer write back caching attributes, in the inner
+shareable domain.
+
+PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
+
+PV lock state
+-------------
+
+The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
+
++-----------+-------------+-------------+---------------------------------+
+| Field | Byte Length | Byte Offset | Description |
++===========+=============+=============+=================================+
+| preempted | 8 | 0 | Indicate if the VCPU that owns |
+| | | | this struct is running or not. |
+| | | | Non-zero values mean the VCPU |
+| | | | has been preempted. Zero means |
+| | | | the VCPU is not preempted. |
++-----------+-------------+-------------+---------------------------------+
+
+The preempted field will be updated to 1 by the hypervisor prior to scheduling
+a VCPU. When the VCPU is scheduled out, the preempted field will be updated
+to 0 by the hypervisor.
+
+The structure will be present within a reserved region of the normal memory
+given to the guest. The guest should not attempt to write into this memory.
+There is a structure per VCPU of the guest.
+
+For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
+section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 716aa3edae14..223ac2fe62f0 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -263,3 +263,26 @@ From the destination VMM process:
7. Write the KVM_VCPU_TSC_OFFSET attribute for every vCPU with the
respective value derived in the previous step.
+
+5. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL
+==================================
+
+:Architectures: ARM64
+
+5.1 ATTRIBUTE: KVM_ARM_VCPU_PVLOCK_IPA
+--------------------------------------
+
+:Parameters: 64-bit base address
+
+Returns:
+
+ ======= ======================================
+ -ENXIO PV lock not implemented
+ -EEXIST Base address already set for this VCPU
+ -EINVAL Base address not 64 byte aligned
+ ======= ======================================
+
+Specifies the base address of the pv lock structure for this VCPU. The
+base address must be 64 byte aligned and exist within a valid guest memory
+region. See Documentation/virt/kvm/arm/pvlock.rst for more information
+including the layout of the pv lock structure.
--
2.25.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 1/6] KVM: arm64: Document PV-lock interface
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Introduce a paravirtualization interface for KVM/arm64 to obtain whether
the VCPU is currently running or not.
The PV lock structure of the guest is allocated by user space.
A hypercall interface is provided for the guest to interrogate the
hypervisor's support for this interface and the location of the shared
memory structures.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
Documentation/virt/kvm/arm/pvlock.rst | 64 +++++++++++++++++++++++++
Documentation/virt/kvm/devices/vcpu.rst | 23 +++++++++
2 files changed, 87 insertions(+)
create mode 100644 Documentation/virt/kvm/arm/pvlock.rst
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
new file mode 100644
index 000000000000..766aeef50b2d
--- /dev/null
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -0,0 +1,64 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Paravirtualized lock support for arm64
+======================================
+
+KVM/arm64 provides hypervisor service calls for paravirtualized guests to check
+whether a VCPU is currently running or not.
+
+Two new SMCCC compatible hypercalls are defined:
+
+* PV_LOCK_FEATURES: 0xC6000020
+* PV_LOCK_PREEMPTED: 0xC6000021
+
+The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
+ARCH_FEATURES mechanism before calling it.
+
+PV_LOCK_FEATURES
+ ============= ======== ==========
+ Function ID: (uint32) 0xC6000020
+ PV_call_id: (uint32) The function to query for support.
+ Currently only PV_LOCK_PREEMPTED is supported.
+ Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
+ PV-lock feature is supported by the hypervisor.
+ ============= ======== ==========
+
+PV_LOCK_PREEMPTED
+ ============= ======== ==========
+ Function ID: (uint32) 0xC6000021
+ Return value: (int64) IPA of the pv lock data structure for this
+ VCPU. On failure:
+ NOT_SUPPORTED (-1)
+ ============= ======== ==========
+
+The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
+memory with inner and outer write back caching attributes, in the inner
+shareable domain.
+
+PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
+
+PV lock state
+-------------
+
+The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
+
++-----------+-------------+-------------+---------------------------------+
+| Field | Byte Length | Byte Offset | Description |
++===========+=============+=============+=================================+
+| preempted | 8 | 0 | Indicate if the VCPU that owns |
+| | | | this struct is running or not. |
+| | | | Non-zero values mean the VCPU |
+| | | | has been preempted. Zero means |
+| | | | the VCPU is not preempted. |
++-----------+-------------+-------------+---------------------------------+
+
+The preempted field will be updated to 1 by the hypervisor prior to scheduling
+a VCPU. When the VCPU is scheduled out, the preempted field will be updated
+to 0 by the hypervisor.
+
+The structure will be present within a reserved region of the normal memory
+given to the guest. The guest should not attempt to write into this memory.
+There is a structure per VCPU of the guest.
+
+For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
+section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 716aa3edae14..223ac2fe62f0 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -263,3 +263,26 @@ From the destination VMM process:
7. Write the KVM_VCPU_TSC_OFFSET attribute for every vCPU with the
respective value derived in the previous step.
+
+5. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL
+==================================
+
+:Architectures: ARM64
+
+5.1 ATTRIBUTE: KVM_ARM_VCPU_PVLOCK_IPA
+--------------------------------------
+
+:Parameters: 64-bit base address
+
+Returns:
+
+ ======= ======================================
+ -ENXIO PV lock not implemented
+ -EEXIST Base address already set for this VCPU
+ -EINVAL Base address not 64 byte aligned
+ ======= ======================================
+
+Specifies the base address of the pv lock structure for this VCPU. The
+base address must be 64 byte aligned and exist within a valid guest memory
+region. See Documentation/virt/kvm/arm/pvlock.rst for more information
+including the layout of the pv lock structure.
--
2.25.1
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 1/6] KVM: arm64: Document PV-lock interface
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma, Usama Arif
Introduce a paravirtualization interface for KVM/arm64 to obtain whether
the VCPU is currently running or not.
The PV lock structure of the guest is allocated by user space.
A hypercall interface is provided for the guest to interrogate the
hypervisor's support for this interface and the location of the shared
memory structures.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
Documentation/virt/kvm/arm/pvlock.rst | 64 +++++++++++++++++++++++++
Documentation/virt/kvm/devices/vcpu.rst | 23 +++++++++
2 files changed, 87 insertions(+)
create mode 100644 Documentation/virt/kvm/arm/pvlock.rst
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
new file mode 100644
index 000000000000..766aeef50b2d
--- /dev/null
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -0,0 +1,64 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Paravirtualized lock support for arm64
+======================================
+
+KVM/arm64 provides hypervisor service calls for paravirtualized guests to check
+whether a VCPU is currently running or not.
+
+Two new SMCCC compatible hypercalls are defined:
+
+* PV_LOCK_FEATURES: 0xC6000020
+* PV_LOCK_PREEMPTED: 0xC6000021
+
+The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
+ARCH_FEATURES mechanism before calling it.
+
+PV_LOCK_FEATURES
+ ============= ======== ==========
+ Function ID: (uint32) 0xC6000020
+ PV_call_id: (uint32) The function to query for support.
+ Currently only PV_LOCK_PREEMPTED is supported.
+ Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
+ PV-lock feature is supported by the hypervisor.
+ ============= ======== ==========
+
+PV_LOCK_PREEMPTED
+ ============= ======== ==========
+ Function ID: (uint32) 0xC6000021
+ Return value: (int64) IPA of the pv lock data structure for this
+ VCPU. On failure:
+ NOT_SUPPORTED (-1)
+ ============= ======== ==========
+
+The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
+memory with inner and outer write back caching attributes, in the inner
+shareable domain.
+
+PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
+
+PV lock state
+-------------
+
+The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
+
++-----------+-------------+-------------+---------------------------------+
+| Field | Byte Length | Byte Offset | Description |
++===========+=============+=============+=================================+
+| preempted | 8 | 0 | Indicate if the VCPU that owns |
+| | | | this struct is running or not. |
+| | | | Non-zero values mean the VCPU |
+| | | | has been preempted. Zero means |
+| | | | the VCPU is not preempted. |
++-----------+-------------+-------------+---------------------------------+
+
+The preempted field will be updated to 1 by the hypervisor prior to scheduling
+a VCPU. When the VCPU is scheduled out, the preempted field will be updated
+to 0 by the hypervisor.
+
+The structure will be present within a reserved region of the normal memory
+given to the guest. The guest should not attempt to write into this memory.
+There is a structure per VCPU of the guest.
+
+For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
+section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 716aa3edae14..223ac2fe62f0 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -263,3 +263,26 @@ From the destination VMM process:
7. Write the KVM_VCPU_TSC_OFFSET attribute for every vCPU with the
respective value derived in the previous step.
+
+5. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL
+==================================
+
+:Architectures: ARM64
+
+5.1 ATTRIBUTE: KVM_ARM_VCPU_PVLOCK_IPA
+--------------------------------------
+
+:Parameters: 64-bit base address
+
+Returns:
+
+ ======= ======================================
+ -ENXIO PV lock not implemented
+ -EEXIST Base address already set for this VCPU
+ -EINVAL Base address not 64 byte aligned
+ ======= ======================================
+
+Specifies the base address of the pv lock structure for this VCPU. The
+base address must be 64 byte aligned and exist within a valid guest memory
+region. See Documentation/virt/kvm/arm/pvlock.rst for more information
+including the layout of the pv lock structure.
--
2.25.1
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 2/6] KVM: arm64: Add SMCCC paravirtualised lock calls
2022-11-02 16:13 ` Usama Arif
(?)
@ 2022-11-02 16:13 ` Usama Arif
-1 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Add two new SMCCC compatible hypercalls for PV lock features:
PV_LOCK_FEATURES: 0xC6000020
PV_LOCK_PREEMPTED: 0xC6000021
Also add the header file which defines the ABI for the paravirtualized
lock features we're about to add.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/pvlock-abi.h | 17 +++++++++++++++++
include/linux/arm-smccc.h | 13 +++++++++++++
2 files changed, 30 insertions(+)
create mode 100644 arch/arm64/include/asm/pvlock-abi.h
diff --git a/arch/arm64/include/asm/pvlock-abi.h b/arch/arm64/include/asm/pvlock-abi.h
new file mode 100644
index 000000000000..3f4574071679
--- /dev/null
+++ b/arch/arm64/include/asm/pvlock-abi.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ * Usama Arif <usama.arif@bytedance.com>
+ */
+
+#ifndef __ASM_PVLOCK_ABI_H
+#define __ASM_PVLOCK_ABI_H
+
+struct pvlock_vcpu_state {
+ __le64 preempted;
+ /* Structure must be 64 byte aligned, pad to that size */
+ u8 padding[56];
+} __packed;
+
+#endif
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 220c8c60e021..6360333e0f64 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -151,6 +151,19 @@
ARM_SMCCC_OWNER_STANDARD_HYP, \
0x21)
+/* Paravirtualised lock calls */
+#define ARM_SMCCC_HV_PV_LOCK_FEATURES \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x20)
+
+#define ARM_SMCCC_HV_PV_LOCK_PREEMPTED \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x21)
+
/* TRNG entropy source calls (defined by ARM DEN0098) */
#define ARM_SMCCC_TRNG_VERSION \
ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
--
2.25.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 2/6] KVM: arm64: Add SMCCC paravirtualised lock calls
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Add two new SMCCC compatible hypercalls for PV lock features:
PV_LOCK_FEATURES: 0xC6000020
PV_LOCK_PREEMPTED: 0xC6000021
Also add the header file which defines the ABI for the paravirtualized
lock features we're about to add.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/pvlock-abi.h | 17 +++++++++++++++++
include/linux/arm-smccc.h | 13 +++++++++++++
2 files changed, 30 insertions(+)
create mode 100644 arch/arm64/include/asm/pvlock-abi.h
diff --git a/arch/arm64/include/asm/pvlock-abi.h b/arch/arm64/include/asm/pvlock-abi.h
new file mode 100644
index 000000000000..3f4574071679
--- /dev/null
+++ b/arch/arm64/include/asm/pvlock-abi.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ * Usama Arif <usama.arif@bytedance.com>
+ */
+
+#ifndef __ASM_PVLOCK_ABI_H
+#define __ASM_PVLOCK_ABI_H
+
+struct pvlock_vcpu_state {
+ __le64 preempted;
+ /* Structure must be 64 byte aligned, pad to that size */
+ u8 padding[56];
+} __packed;
+
+#endif
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 220c8c60e021..6360333e0f64 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -151,6 +151,19 @@
ARM_SMCCC_OWNER_STANDARD_HYP, \
0x21)
+/* Paravirtualised lock calls */
+#define ARM_SMCCC_HV_PV_LOCK_FEATURES \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x20)
+
+#define ARM_SMCCC_HV_PV_LOCK_PREEMPTED \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x21)
+
/* TRNG entropy source calls (defined by ARM DEN0098) */
#define ARM_SMCCC_TRNG_VERSION \
ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
--
2.25.1
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 2/6] KVM: arm64: Add SMCCC paravirtualised lock calls
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma, Usama Arif
Add two new SMCCC compatible hypercalls for PV lock features:
PV_LOCK_FEATURES: 0xC6000020
PV_LOCK_PREEMPTED: 0xC6000021
Also add the header file which defines the ABI for the paravirtualized
lock features we're about to add.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/pvlock-abi.h | 17 +++++++++++++++++
include/linux/arm-smccc.h | 13 +++++++++++++
2 files changed, 30 insertions(+)
create mode 100644 arch/arm64/include/asm/pvlock-abi.h
diff --git a/arch/arm64/include/asm/pvlock-abi.h b/arch/arm64/include/asm/pvlock-abi.h
new file mode 100644
index 000000000000..3f4574071679
--- /dev/null
+++ b/arch/arm64/include/asm/pvlock-abi.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ * Usama Arif <usama.arif@bytedance.com>
+ */
+
+#ifndef __ASM_PVLOCK_ABI_H
+#define __ASM_PVLOCK_ABI_H
+
+struct pvlock_vcpu_state {
+ __le64 preempted;
+ /* Structure must be 64 byte aligned, pad to that size */
+ u8 padding[56];
+} __packed;
+
+#endif
diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
index 220c8c60e021..6360333e0f64 100644
--- a/include/linux/arm-smccc.h
+++ b/include/linux/arm-smccc.h
@@ -151,6 +151,19 @@
ARM_SMCCC_OWNER_STANDARD_HYP, \
0x21)
+/* Paravirtualised lock calls */
+#define ARM_SMCCC_HV_PV_LOCK_FEATURES \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x20)
+
+#define ARM_SMCCC_HV_PV_LOCK_PREEMPTED \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x21)
+
/* TRNG entropy source calls (defined by ARM DEN0098) */
#define ARM_SMCCC_TRNG_VERSION \
ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
--
2.25.1
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 3/6] KVM: arm64: Support pvlock preempted via shared structure
2022-11-02 16:13 ` Usama Arif
(?)
@ 2022-11-02 16:13 ` Usama Arif
-1 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Implement the service call for configuring a shared structure between a
VCPU and the hypervisor in which the hypervisor can tell whether the
VCPU is running or not.
The preempted field is zero if the VCPU is not preempted.
Any other value means the VCPU has been preempted.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
Documentation/virt/kvm/arm/hypercalls.rst | 3 ++
arch/arm64/include/asm/kvm_host.h | 18 ++++++++++
arch/arm64/include/uapi/asm/kvm.h | 1 +
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arm.c | 8 +++++
arch/arm64/kvm/hypercalls.c | 36 +++++++++++++++++++
arch/arm64/kvm/pvlock.c | 43 +++++++++++++++++++++++
arch/arm64/kvm/pvtime.c | 16 ---------
tools/arch/arm64/include/uapi/asm/kvm.h | 1 +
tools/include/linux/arm-smccc.h | 13 +++++++
10 files changed, 124 insertions(+), 17 deletions(-)
create mode 100644 arch/arm64/kvm/pvlock.c
diff --git a/Documentation/virt/kvm/arm/hypercalls.rst b/Documentation/virt/kvm/arm/hypercalls.rst
index 3e23084644ba..872a16226ace 100644
--- a/Documentation/virt/kvm/arm/hypercalls.rst
+++ b/Documentation/virt/kvm/arm/hypercalls.rst
@@ -127,6 +127,9 @@ The pseudo-firmware bitmap register are as follows:
Bit-1: KVM_REG_ARM_VENDOR_HYP_BIT_PTP:
The bit represents the Precision Time Protocol KVM service.
+ Bit-2: KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK:
+ The bit represents the Paravirtualized lock service.
+
Errors:
======= =============================================================
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 45e2136322ba..18303b30b7e9 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -417,6 +417,11 @@ struct kvm_vcpu_arch {
u64 last_steal;
gpa_t base;
} steal;
+
+ /* Guest PV lock state */
+ struct {
+ gpa_t base;
+ } pv;
};
/*
@@ -840,6 +845,19 @@ static inline bool kvm_arm_is_pvtime_enabled(struct kvm_vcpu_arch *vcpu_arch)
return (vcpu_arch->steal.base != GPA_INVALID);
}
+static inline void kvm_arm_pvlock_preempted_init(struct kvm_vcpu_arch *vcpu_arch)
+{
+ vcpu_arch->pv.base = GPA_INVALID;
+}
+
+static inline bool kvm_arm_is_pvlock_preempted_ready(struct kvm_vcpu_arch *vcpu_arch)
+{
+ return (vcpu_arch->pv.base != GPA_INVALID);
+}
+
+gpa_t kvm_init_pvlock(struct kvm_vcpu *vcpu);
+void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted);
+
void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome);
struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 316917b98707..bd05ece5c590 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -365,6 +365,7 @@ enum {
enum {
KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT = 0,
KVM_REG_ARM_VENDOR_HYP_BIT_PTP = 1,
+ KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK = 2,
#ifdef __KERNEL__
KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT,
#endif
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 5e33c2d4645a..e1f711885916 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -10,7 +10,7 @@ include $(srctree)/virt/kvm/Makefile.kvm
obj-$(CONFIG_KVM) += kvm.o
obj-$(CONFIG_KVM) += hyp/
-kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
+kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o pvlock.o \
inject_fault.o va_layout.o handle_exit.o \
guest.o debug.o reset.o sys_regs.o stacktrace.o \
vgic-sys-reg-v3.o fpsimd.o pkvm.o \
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 94d33e296e10..73da4ac859fd 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -345,6 +345,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
kvm_arm_pvtime_vcpu_init(&vcpu->arch);
+ kvm_arm_pvlock_preempted_init(&vcpu->arch);
+
vcpu->arch.hw_mmu = &vcpu->kvm->arch.mmu;
err = kvm_vgic_vcpu_init(vcpu);
@@ -420,6 +422,10 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if (vcpu_has_ptrauth(vcpu))
vcpu_ptrauth_disable(vcpu);
+
+ if (kvm_arm_is_pvlock_preempted_ready(&vcpu->arch))
+ kvm_update_pvlock_preempted(vcpu, 0);
+
kvm_arch_vcpu_load_debug_state_flags(vcpu);
if (!cpumask_test_cpu(smp_processor_id(), vcpu->kvm->arch.supported_cpus))
@@ -433,6 +439,8 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
if (has_vhe())
kvm_vcpu_put_sysregs_vhe(vcpu);
kvm_timer_vcpu_put(vcpu);
+ if (kvm_arm_is_pvlock_preempted_ready(&vcpu->arch))
+ kvm_update_pvlock_preempted(vcpu, 1);
kvm_vgic_put(vcpu);
kvm_vcpu_pmu_restore_host(vcpu);
kvm_arm_vmid_clear_active();
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index c9f401fa01a9..263500c4f20e 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -93,6 +93,27 @@ static bool kvm_hvc_call_default_allowed(u32 func_id)
}
}
+long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
+{
+ u32 feature = smccc_get_arg1(vcpu);
+ long val = SMCCC_RET_NOT_SUPPORTED;
+
+ switch (feature) {
+ case ARM_SMCCC_HV_PV_TIME_FEATURES:
+ case ARM_SMCCC_HV_PV_TIME_ST:
+ if (vcpu->arch.steal.base != GPA_INVALID)
+ val = SMCCC_RET_SUCCESS;
+ break;
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ if (vcpu->arch.pv.base != GPA_INVALID)
+ val = SMCCC_RET_SUCCESS;
+ break;
+ }
+
+ return val;
+}
+
static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
{
struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
@@ -109,6 +130,10 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
case ARM_SMCCC_HV_PV_TIME_ST:
return test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
&smccc_feat->std_hyp_bmap);
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK,
+ &smccc_feat->vendor_hyp_bmap);
case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT,
@@ -191,9 +216,15 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
&smccc_feat->std_hyp_bmap))
val[0] = SMCCC_RET_SUCCESS;
break;
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ if (test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK,
+ &smccc_feat->vendor_hyp_bmap))
+ val[0] = SMCCC_RET_SUCCESS;
+ break;
}
break;
case ARM_SMCCC_HV_PV_TIME_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
val[0] = kvm_hypercall_pv_features(vcpu);
break;
case ARM_SMCCC_HV_PV_TIME_ST:
@@ -201,6 +232,11 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
if (gpa != GPA_INVALID)
val[0] = gpa;
break;
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ gpa = kvm_init_pvlock(vcpu);
+ if (gpa != GPA_INVALID)
+ val[0] = gpa;
+ break;
case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
val[0] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0;
val[1] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1;
diff --git a/arch/arm64/kvm/pvlock.c b/arch/arm64/kvm/pvlock.c
new file mode 100644
index 000000000000..3eb35ab31481
--- /dev/null
+++ b/arch/arm64/kvm/pvlock.c
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ * Usama Arif <usama.arif@bytedance.com>
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/kvm_host.h>
+
+#include <asm/pvlock-abi.h>
+
+#include <kvm/arm_hypercalls.h>
+
+gpa_t kvm_init_pvlock(struct kvm_vcpu *vcpu)
+{
+ struct pvlock_vcpu_state init_values = {};
+ struct kvm *kvm = vcpu->kvm;
+ u64 base = vcpu->arch.pv.base;
+ int idx;
+
+ if (base == GPA_INVALID)
+ return base;
+
+ idx = srcu_read_lock(&kvm->srcu);
+ kvm_write_guest(kvm, base, &init_values, sizeof(init_values));
+ srcu_read_unlock(&kvm->srcu, idx);
+
+ return base;
+}
+
+void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted)
+{
+ int idx;
+ u64 offset;
+ struct kvm *kvm = vcpu->kvm;
+ u64 base = vcpu->arch.pv.base;
+
+ idx = srcu_read_lock(&kvm->srcu);
+ offset = offsetof(struct pvlock_vcpu_state, preempted);
+ kvm_put_guest(kvm, base + offset, cpu_to_le64(preempted));
+ srcu_read_unlock(&kvm->srcu, idx);
+}
diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c
index 78a09f7a6637..ab130f02cdc6 100644
--- a/arch/arm64/kvm/pvtime.c
+++ b/arch/arm64/kvm/pvtime.c
@@ -32,22 +32,6 @@ void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
srcu_read_unlock(&kvm->srcu, idx);
}
-long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
-{
- u32 feature = smccc_get_arg1(vcpu);
- long val = SMCCC_RET_NOT_SUPPORTED;
-
- switch (feature) {
- case ARM_SMCCC_HV_PV_TIME_FEATURES:
- case ARM_SMCCC_HV_PV_TIME_ST:
- if (vcpu->arch.steal.base != GPA_INVALID)
- val = SMCCC_RET_SUCCESS;
- break;
- }
-
- return val;
-}
-
gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu)
{
struct pvclock_vcpu_stolen_time init_values = {};
diff --git a/tools/arch/arm64/include/uapi/asm/kvm.h b/tools/arch/arm64/include/uapi/asm/kvm.h
index 316917b98707..bd05ece5c590 100644
--- a/tools/arch/arm64/include/uapi/asm/kvm.h
+++ b/tools/arch/arm64/include/uapi/asm/kvm.h
@@ -365,6 +365,7 @@ enum {
enum {
KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT = 0,
KVM_REG_ARM_VENDOR_HYP_BIT_PTP = 1,
+ KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK = 2,
#ifdef __KERNEL__
KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT,
#endif
diff --git a/tools/include/linux/arm-smccc.h b/tools/include/linux/arm-smccc.h
index 63ce9bebccd3..82b4fd050dd7 100644
--- a/tools/include/linux/arm-smccc.h
+++ b/tools/include/linux/arm-smccc.h
@@ -150,6 +150,19 @@
ARM_SMCCC_OWNER_STANDARD_HYP, \
0x21)
+/* Paravirtualised lock calls */
+#define ARM_SMCCC_HV_PV_LOCK_FEATURES \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x20)
+
+#define ARM_SMCCC_HV_PV_LOCK_PREEMPTED \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x21)
+
/* TRNG entropy source calls (defined by ARM DEN0098) */
#define ARM_SMCCC_TRNG_VERSION \
ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
--
2.25.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 3/6] KVM: arm64: Support pvlock preempted via shared structure
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Implement the service call for configuring a shared structure between a
VCPU and the hypervisor in which the hypervisor can tell whether the
VCPU is running or not.
The preempted field is zero if the VCPU is not preempted.
Any other value means the VCPU has been preempted.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
Documentation/virt/kvm/arm/hypercalls.rst | 3 ++
arch/arm64/include/asm/kvm_host.h | 18 ++++++++++
arch/arm64/include/uapi/asm/kvm.h | 1 +
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arm.c | 8 +++++
arch/arm64/kvm/hypercalls.c | 36 +++++++++++++++++++
arch/arm64/kvm/pvlock.c | 43 +++++++++++++++++++++++
arch/arm64/kvm/pvtime.c | 16 ---------
tools/arch/arm64/include/uapi/asm/kvm.h | 1 +
tools/include/linux/arm-smccc.h | 13 +++++++
10 files changed, 124 insertions(+), 17 deletions(-)
create mode 100644 arch/arm64/kvm/pvlock.c
diff --git a/Documentation/virt/kvm/arm/hypercalls.rst b/Documentation/virt/kvm/arm/hypercalls.rst
index 3e23084644ba..872a16226ace 100644
--- a/Documentation/virt/kvm/arm/hypercalls.rst
+++ b/Documentation/virt/kvm/arm/hypercalls.rst
@@ -127,6 +127,9 @@ The pseudo-firmware bitmap register are as follows:
Bit-1: KVM_REG_ARM_VENDOR_HYP_BIT_PTP:
The bit represents the Precision Time Protocol KVM service.
+ Bit-2: KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK:
+ The bit represents the Paravirtualized lock service.
+
Errors:
======= =============================================================
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 45e2136322ba..18303b30b7e9 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -417,6 +417,11 @@ struct kvm_vcpu_arch {
u64 last_steal;
gpa_t base;
} steal;
+
+ /* Guest PV lock state */
+ struct {
+ gpa_t base;
+ } pv;
};
/*
@@ -840,6 +845,19 @@ static inline bool kvm_arm_is_pvtime_enabled(struct kvm_vcpu_arch *vcpu_arch)
return (vcpu_arch->steal.base != GPA_INVALID);
}
+static inline void kvm_arm_pvlock_preempted_init(struct kvm_vcpu_arch *vcpu_arch)
+{
+ vcpu_arch->pv.base = GPA_INVALID;
+}
+
+static inline bool kvm_arm_is_pvlock_preempted_ready(struct kvm_vcpu_arch *vcpu_arch)
+{
+ return (vcpu_arch->pv.base != GPA_INVALID);
+}
+
+gpa_t kvm_init_pvlock(struct kvm_vcpu *vcpu);
+void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted);
+
void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome);
struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 316917b98707..bd05ece5c590 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -365,6 +365,7 @@ enum {
enum {
KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT = 0,
KVM_REG_ARM_VENDOR_HYP_BIT_PTP = 1,
+ KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK = 2,
#ifdef __KERNEL__
KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT,
#endif
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 5e33c2d4645a..e1f711885916 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -10,7 +10,7 @@ include $(srctree)/virt/kvm/Makefile.kvm
obj-$(CONFIG_KVM) += kvm.o
obj-$(CONFIG_KVM) += hyp/
-kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
+kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o pvlock.o \
inject_fault.o va_layout.o handle_exit.o \
guest.o debug.o reset.o sys_regs.o stacktrace.o \
vgic-sys-reg-v3.o fpsimd.o pkvm.o \
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 94d33e296e10..73da4ac859fd 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -345,6 +345,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
kvm_arm_pvtime_vcpu_init(&vcpu->arch);
+ kvm_arm_pvlock_preempted_init(&vcpu->arch);
+
vcpu->arch.hw_mmu = &vcpu->kvm->arch.mmu;
err = kvm_vgic_vcpu_init(vcpu);
@@ -420,6 +422,10 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if (vcpu_has_ptrauth(vcpu))
vcpu_ptrauth_disable(vcpu);
+
+ if (kvm_arm_is_pvlock_preempted_ready(&vcpu->arch))
+ kvm_update_pvlock_preempted(vcpu, 0);
+
kvm_arch_vcpu_load_debug_state_flags(vcpu);
if (!cpumask_test_cpu(smp_processor_id(), vcpu->kvm->arch.supported_cpus))
@@ -433,6 +439,8 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
if (has_vhe())
kvm_vcpu_put_sysregs_vhe(vcpu);
kvm_timer_vcpu_put(vcpu);
+ if (kvm_arm_is_pvlock_preempted_ready(&vcpu->arch))
+ kvm_update_pvlock_preempted(vcpu, 1);
kvm_vgic_put(vcpu);
kvm_vcpu_pmu_restore_host(vcpu);
kvm_arm_vmid_clear_active();
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index c9f401fa01a9..263500c4f20e 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -93,6 +93,27 @@ static bool kvm_hvc_call_default_allowed(u32 func_id)
}
}
+long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
+{
+ u32 feature = smccc_get_arg1(vcpu);
+ long val = SMCCC_RET_NOT_SUPPORTED;
+
+ switch (feature) {
+ case ARM_SMCCC_HV_PV_TIME_FEATURES:
+ case ARM_SMCCC_HV_PV_TIME_ST:
+ if (vcpu->arch.steal.base != GPA_INVALID)
+ val = SMCCC_RET_SUCCESS;
+ break;
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ if (vcpu->arch.pv.base != GPA_INVALID)
+ val = SMCCC_RET_SUCCESS;
+ break;
+ }
+
+ return val;
+}
+
static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
{
struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
@@ -109,6 +130,10 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
case ARM_SMCCC_HV_PV_TIME_ST:
return test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
&smccc_feat->std_hyp_bmap);
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK,
+ &smccc_feat->vendor_hyp_bmap);
case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT,
@@ -191,9 +216,15 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
&smccc_feat->std_hyp_bmap))
val[0] = SMCCC_RET_SUCCESS;
break;
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ if (test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK,
+ &smccc_feat->vendor_hyp_bmap))
+ val[0] = SMCCC_RET_SUCCESS;
+ break;
}
break;
case ARM_SMCCC_HV_PV_TIME_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
val[0] = kvm_hypercall_pv_features(vcpu);
break;
case ARM_SMCCC_HV_PV_TIME_ST:
@@ -201,6 +232,11 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
if (gpa != GPA_INVALID)
val[0] = gpa;
break;
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ gpa = kvm_init_pvlock(vcpu);
+ if (gpa != GPA_INVALID)
+ val[0] = gpa;
+ break;
case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
val[0] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0;
val[1] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1;
diff --git a/arch/arm64/kvm/pvlock.c b/arch/arm64/kvm/pvlock.c
new file mode 100644
index 000000000000..3eb35ab31481
--- /dev/null
+++ b/arch/arm64/kvm/pvlock.c
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ * Usama Arif <usama.arif@bytedance.com>
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/kvm_host.h>
+
+#include <asm/pvlock-abi.h>
+
+#include <kvm/arm_hypercalls.h>
+
+gpa_t kvm_init_pvlock(struct kvm_vcpu *vcpu)
+{
+ struct pvlock_vcpu_state init_values = {};
+ struct kvm *kvm = vcpu->kvm;
+ u64 base = vcpu->arch.pv.base;
+ int idx;
+
+ if (base == GPA_INVALID)
+ return base;
+
+ idx = srcu_read_lock(&kvm->srcu);
+ kvm_write_guest(kvm, base, &init_values, sizeof(init_values));
+ srcu_read_unlock(&kvm->srcu, idx);
+
+ return base;
+}
+
+void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted)
+{
+ int idx;
+ u64 offset;
+ struct kvm *kvm = vcpu->kvm;
+ u64 base = vcpu->arch.pv.base;
+
+ idx = srcu_read_lock(&kvm->srcu);
+ offset = offsetof(struct pvlock_vcpu_state, preempted);
+ kvm_put_guest(kvm, base + offset, cpu_to_le64(preempted));
+ srcu_read_unlock(&kvm->srcu, idx);
+}
diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c
index 78a09f7a6637..ab130f02cdc6 100644
--- a/arch/arm64/kvm/pvtime.c
+++ b/arch/arm64/kvm/pvtime.c
@@ -32,22 +32,6 @@ void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
srcu_read_unlock(&kvm->srcu, idx);
}
-long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
-{
- u32 feature = smccc_get_arg1(vcpu);
- long val = SMCCC_RET_NOT_SUPPORTED;
-
- switch (feature) {
- case ARM_SMCCC_HV_PV_TIME_FEATURES:
- case ARM_SMCCC_HV_PV_TIME_ST:
- if (vcpu->arch.steal.base != GPA_INVALID)
- val = SMCCC_RET_SUCCESS;
- break;
- }
-
- return val;
-}
-
gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu)
{
struct pvclock_vcpu_stolen_time init_values = {};
diff --git a/tools/arch/arm64/include/uapi/asm/kvm.h b/tools/arch/arm64/include/uapi/asm/kvm.h
index 316917b98707..bd05ece5c590 100644
--- a/tools/arch/arm64/include/uapi/asm/kvm.h
+++ b/tools/arch/arm64/include/uapi/asm/kvm.h
@@ -365,6 +365,7 @@ enum {
enum {
KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT = 0,
KVM_REG_ARM_VENDOR_HYP_BIT_PTP = 1,
+ KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK = 2,
#ifdef __KERNEL__
KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT,
#endif
diff --git a/tools/include/linux/arm-smccc.h b/tools/include/linux/arm-smccc.h
index 63ce9bebccd3..82b4fd050dd7 100644
--- a/tools/include/linux/arm-smccc.h
+++ b/tools/include/linux/arm-smccc.h
@@ -150,6 +150,19 @@
ARM_SMCCC_OWNER_STANDARD_HYP, \
0x21)
+/* Paravirtualised lock calls */
+#define ARM_SMCCC_HV_PV_LOCK_FEATURES \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x20)
+
+#define ARM_SMCCC_HV_PV_LOCK_PREEMPTED \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x21)
+
/* TRNG entropy source calls (defined by ARM DEN0098) */
#define ARM_SMCCC_TRNG_VERSION \
ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
--
2.25.1
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 3/6] KVM: arm64: Support pvlock preempted via shared structure
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma, Usama Arif
Implement the service call for configuring a shared structure between a
VCPU and the hypervisor in which the hypervisor can tell whether the
VCPU is running or not.
The preempted field is zero if the VCPU is not preempted.
Any other value means the VCPU has been preempted.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
Documentation/virt/kvm/arm/hypercalls.rst | 3 ++
arch/arm64/include/asm/kvm_host.h | 18 ++++++++++
arch/arm64/include/uapi/asm/kvm.h | 1 +
arch/arm64/kvm/Makefile | 2 +-
arch/arm64/kvm/arm.c | 8 +++++
arch/arm64/kvm/hypercalls.c | 36 +++++++++++++++++++
arch/arm64/kvm/pvlock.c | 43 +++++++++++++++++++++++
arch/arm64/kvm/pvtime.c | 16 ---------
tools/arch/arm64/include/uapi/asm/kvm.h | 1 +
tools/include/linux/arm-smccc.h | 13 +++++++
10 files changed, 124 insertions(+), 17 deletions(-)
create mode 100644 arch/arm64/kvm/pvlock.c
diff --git a/Documentation/virt/kvm/arm/hypercalls.rst b/Documentation/virt/kvm/arm/hypercalls.rst
index 3e23084644ba..872a16226ace 100644
--- a/Documentation/virt/kvm/arm/hypercalls.rst
+++ b/Documentation/virt/kvm/arm/hypercalls.rst
@@ -127,6 +127,9 @@ The pseudo-firmware bitmap register are as follows:
Bit-1: KVM_REG_ARM_VENDOR_HYP_BIT_PTP:
The bit represents the Precision Time Protocol KVM service.
+ Bit-2: KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK:
+ The bit represents the Paravirtualized lock service.
+
Errors:
======= =============================================================
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 45e2136322ba..18303b30b7e9 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -417,6 +417,11 @@ struct kvm_vcpu_arch {
u64 last_steal;
gpa_t base;
} steal;
+
+ /* Guest PV lock state */
+ struct {
+ gpa_t base;
+ } pv;
};
/*
@@ -840,6 +845,19 @@ static inline bool kvm_arm_is_pvtime_enabled(struct kvm_vcpu_arch *vcpu_arch)
return (vcpu_arch->steal.base != GPA_INVALID);
}
+static inline void kvm_arm_pvlock_preempted_init(struct kvm_vcpu_arch *vcpu_arch)
+{
+ vcpu_arch->pv.base = GPA_INVALID;
+}
+
+static inline bool kvm_arm_is_pvlock_preempted_ready(struct kvm_vcpu_arch *vcpu_arch)
+{
+ return (vcpu_arch->pv.base != GPA_INVALID);
+}
+
+gpa_t kvm_init_pvlock(struct kvm_vcpu *vcpu);
+void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted);
+
void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome);
struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index 316917b98707..bd05ece5c590 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -365,6 +365,7 @@ enum {
enum {
KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT = 0,
KVM_REG_ARM_VENDOR_HYP_BIT_PTP = 1,
+ KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK = 2,
#ifdef __KERNEL__
KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT,
#endif
diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
index 5e33c2d4645a..e1f711885916 100644
--- a/arch/arm64/kvm/Makefile
+++ b/arch/arm64/kvm/Makefile
@@ -10,7 +10,7 @@ include $(srctree)/virt/kvm/Makefile.kvm
obj-$(CONFIG_KVM) += kvm.o
obj-$(CONFIG_KVM) += hyp/
-kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
+kvm-y += arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o pvlock.o \
inject_fault.o va_layout.o handle_exit.o \
guest.o debug.o reset.o sys_regs.o stacktrace.o \
vgic-sys-reg-v3.o fpsimd.o pkvm.o \
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 94d33e296e10..73da4ac859fd 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -345,6 +345,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
kvm_arm_pvtime_vcpu_init(&vcpu->arch);
+ kvm_arm_pvlock_preempted_init(&vcpu->arch);
+
vcpu->arch.hw_mmu = &vcpu->kvm->arch.mmu;
err = kvm_vgic_vcpu_init(vcpu);
@@ -420,6 +422,10 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if (vcpu_has_ptrauth(vcpu))
vcpu_ptrauth_disable(vcpu);
+
+ if (kvm_arm_is_pvlock_preempted_ready(&vcpu->arch))
+ kvm_update_pvlock_preempted(vcpu, 0);
+
kvm_arch_vcpu_load_debug_state_flags(vcpu);
if (!cpumask_test_cpu(smp_processor_id(), vcpu->kvm->arch.supported_cpus))
@@ -433,6 +439,8 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
if (has_vhe())
kvm_vcpu_put_sysregs_vhe(vcpu);
kvm_timer_vcpu_put(vcpu);
+ if (kvm_arm_is_pvlock_preempted_ready(&vcpu->arch))
+ kvm_update_pvlock_preempted(vcpu, 1);
kvm_vgic_put(vcpu);
kvm_vcpu_pmu_restore_host(vcpu);
kvm_arm_vmid_clear_active();
diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c
index c9f401fa01a9..263500c4f20e 100644
--- a/arch/arm64/kvm/hypercalls.c
+++ b/arch/arm64/kvm/hypercalls.c
@@ -93,6 +93,27 @@ static bool kvm_hvc_call_default_allowed(u32 func_id)
}
}
+long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
+{
+ u32 feature = smccc_get_arg1(vcpu);
+ long val = SMCCC_RET_NOT_SUPPORTED;
+
+ switch (feature) {
+ case ARM_SMCCC_HV_PV_TIME_FEATURES:
+ case ARM_SMCCC_HV_PV_TIME_ST:
+ if (vcpu->arch.steal.base != GPA_INVALID)
+ val = SMCCC_RET_SUCCESS;
+ break;
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ if (vcpu->arch.pv.base != GPA_INVALID)
+ val = SMCCC_RET_SUCCESS;
+ break;
+ }
+
+ return val;
+}
+
static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
{
struct kvm_smccc_features *smccc_feat = &vcpu->kvm->arch.smccc_feat;
@@ -109,6 +130,10 @@ static bool kvm_hvc_call_allowed(struct kvm_vcpu *vcpu, u32 func_id)
case ARM_SMCCC_HV_PV_TIME_ST:
return test_bit(KVM_REG_ARM_STD_HYP_BIT_PV_TIME,
&smccc_feat->std_hyp_bmap);
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK,
+ &smccc_feat->vendor_hyp_bmap);
case ARM_SMCCC_VENDOR_HYP_KVM_FEATURES_FUNC_ID:
case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
return test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT,
@@ -191,9 +216,15 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
&smccc_feat->std_hyp_bmap))
val[0] = SMCCC_RET_SUCCESS;
break;
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
+ if (test_bit(KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK,
+ &smccc_feat->vendor_hyp_bmap))
+ val[0] = SMCCC_RET_SUCCESS;
+ break;
}
break;
case ARM_SMCCC_HV_PV_TIME_FEATURES:
+ case ARM_SMCCC_HV_PV_LOCK_FEATURES:
val[0] = kvm_hypercall_pv_features(vcpu);
break;
case ARM_SMCCC_HV_PV_TIME_ST:
@@ -201,6 +232,11 @@ int kvm_hvc_call_handler(struct kvm_vcpu *vcpu)
if (gpa != GPA_INVALID)
val[0] = gpa;
break;
+ case ARM_SMCCC_HV_PV_LOCK_PREEMPTED:
+ gpa = kvm_init_pvlock(vcpu);
+ if (gpa != GPA_INVALID)
+ val[0] = gpa;
+ break;
case ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID:
val[0] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_0;
val[1] = ARM_SMCCC_VENDOR_HYP_UID_KVM_REG_1;
diff --git a/arch/arm64/kvm/pvlock.c b/arch/arm64/kvm/pvlock.c
new file mode 100644
index 000000000000..3eb35ab31481
--- /dev/null
+++ b/arch/arm64/kvm/pvlock.c
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright(c) 2019 Huawei Technologies Co., Ltd
+ * Author: Zengruan Ye <yezengruan@huawei.com>
+ * Usama Arif <usama.arif@bytedance.com>
+ */
+
+#include <linux/arm-smccc.h>
+#include <linux/kvm_host.h>
+
+#include <asm/pvlock-abi.h>
+
+#include <kvm/arm_hypercalls.h>
+
+gpa_t kvm_init_pvlock(struct kvm_vcpu *vcpu)
+{
+ struct pvlock_vcpu_state init_values = {};
+ struct kvm *kvm = vcpu->kvm;
+ u64 base = vcpu->arch.pv.base;
+ int idx;
+
+ if (base == GPA_INVALID)
+ return base;
+
+ idx = srcu_read_lock(&kvm->srcu);
+ kvm_write_guest(kvm, base, &init_values, sizeof(init_values));
+ srcu_read_unlock(&kvm->srcu, idx);
+
+ return base;
+}
+
+void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted)
+{
+ int idx;
+ u64 offset;
+ struct kvm *kvm = vcpu->kvm;
+ u64 base = vcpu->arch.pv.base;
+
+ idx = srcu_read_lock(&kvm->srcu);
+ offset = offsetof(struct pvlock_vcpu_state, preempted);
+ kvm_put_guest(kvm, base + offset, cpu_to_le64(preempted));
+ srcu_read_unlock(&kvm->srcu, idx);
+}
diff --git a/arch/arm64/kvm/pvtime.c b/arch/arm64/kvm/pvtime.c
index 78a09f7a6637..ab130f02cdc6 100644
--- a/arch/arm64/kvm/pvtime.c
+++ b/arch/arm64/kvm/pvtime.c
@@ -32,22 +32,6 @@ void kvm_update_stolen_time(struct kvm_vcpu *vcpu)
srcu_read_unlock(&kvm->srcu, idx);
}
-long kvm_hypercall_pv_features(struct kvm_vcpu *vcpu)
-{
- u32 feature = smccc_get_arg1(vcpu);
- long val = SMCCC_RET_NOT_SUPPORTED;
-
- switch (feature) {
- case ARM_SMCCC_HV_PV_TIME_FEATURES:
- case ARM_SMCCC_HV_PV_TIME_ST:
- if (vcpu->arch.steal.base != GPA_INVALID)
- val = SMCCC_RET_SUCCESS;
- break;
- }
-
- return val;
-}
-
gpa_t kvm_init_stolen_time(struct kvm_vcpu *vcpu)
{
struct pvclock_vcpu_stolen_time init_values = {};
diff --git a/tools/arch/arm64/include/uapi/asm/kvm.h b/tools/arch/arm64/include/uapi/asm/kvm.h
index 316917b98707..bd05ece5c590 100644
--- a/tools/arch/arm64/include/uapi/asm/kvm.h
+++ b/tools/arch/arm64/include/uapi/asm/kvm.h
@@ -365,6 +365,7 @@ enum {
enum {
KVM_REG_ARM_VENDOR_HYP_BIT_FUNC_FEAT = 0,
KVM_REG_ARM_VENDOR_HYP_BIT_PTP = 1,
+ KVM_REG_ARM_VENDOR_HYP_BIT_PV_LOCK = 2,
#ifdef __KERNEL__
KVM_REG_ARM_VENDOR_HYP_BMAP_BIT_COUNT,
#endif
diff --git a/tools/include/linux/arm-smccc.h b/tools/include/linux/arm-smccc.h
index 63ce9bebccd3..82b4fd050dd7 100644
--- a/tools/include/linux/arm-smccc.h
+++ b/tools/include/linux/arm-smccc.h
@@ -150,6 +150,19 @@
ARM_SMCCC_OWNER_STANDARD_HYP, \
0x21)
+/* Paravirtualised lock calls */
+#define ARM_SMCCC_HV_PV_LOCK_FEATURES \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x20)
+
+#define ARM_SMCCC_HV_PV_LOCK_PREEMPTED \
+ ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
+ ARM_SMCCC_SMC_64, \
+ ARM_SMCCC_OWNER_VENDOR_HYP, \
+ 0x21)
+
/* TRNG entropy source calls (defined by ARM DEN0098) */
#define ARM_SMCCC_TRNG_VERSION \
ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, \
--
2.25.1
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 4/6] KVM: arm64: Provide VCPU attributes for PV lock
2022-11-02 16:13 ` Usama Arif
(?)
@ 2022-11-02 16:13 ` Usama Arif
-1 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Allow user space to inform the KVM host where in the physical memory
map the paravirtualized lock structures should be located.
User space can set an attribute on the VCPU providing the IPA base
address of the PV lock structure for that VCPU. This must be
repeated for every VCPU in the VM.
The address is given in terms of the physical address visible to
the guest and must be 64 byte aligned. The guest will discover the
address via a hypercall.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/kvm_host.h | 7 ++++
arch/arm64/include/uapi/asm/kvm.h | 2 ++
arch/arm64/kvm/guest.c | 9 +++++
arch/arm64/kvm/pvlock.c | 57 +++++++++++++++++++++++++++++++
include/uapi/linux/kvm.h | 2 ++
5 files changed, 77 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 18303b30b7e9..86aeca8a4393 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -829,6 +829,13 @@ int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu,
int kvm_arm_pvtime_has_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr);
+int kvm_arm_pvlock_set_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+int kvm_arm_pvlock_get_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+int kvm_arm_pvlock_has_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+
extern unsigned int kvm_arm_vmid_bits;
int kvm_arm_vmid_alloc_init(void);
void kvm_arm_vmid_alloc_free(void);
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index bd05ece5c590..71010bacaaab 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -412,6 +412,8 @@ enum {
#define KVM_ARM_VCPU_TIMER_IRQ_PTIMER 1
#define KVM_ARM_VCPU_PVTIME_CTRL 2
#define KVM_ARM_VCPU_PVTIME_IPA 0
+#define KVM_ARM_VCPU_PVLOCK_CTRL 3
+#define KVM_ARM_VCPU_PVLOCK_IPA 0
/* KVM_IRQ_LINE irq field index values */
#define KVM_ARM_IRQ_VCPU2_SHIFT 28
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 2ff13a3f8479..7e765e3256ef 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -959,6 +959,9 @@ int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_set_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_set_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -982,6 +985,9 @@ int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_get_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_get_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -1005,6 +1011,9 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_has_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_has_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
diff --git a/arch/arm64/kvm/pvlock.c b/arch/arm64/kvm/pvlock.c
index 3eb35ab31481..b08a287a4811 100644
--- a/arch/arm64/kvm/pvlock.c
+++ b/arch/arm64/kvm/pvlock.c
@@ -41,3 +41,60 @@ void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted)
kvm_put_guest(kvm, base + offset, cpu_to_le64(preempted));
srcu_read_unlock(&kvm->srcu, idx);
}
+
+int kvm_arm_pvlock_set_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ u64 __user *user = (u64 __user *)attr->addr;
+ struct kvm *kvm = vcpu->kvm;
+ u64 ipa;
+ int ret = 0;
+ int idx;
+
+ if (attr->attr != KVM_ARM_VCPU_PVLOCK_IPA)
+ return -ENXIO;
+
+ if (get_user(ipa, user))
+ return -EFAULT;
+ if (!IS_ALIGNED(ipa, 64))
+ return -EINVAL;
+ if (vcpu->arch.pv.base != GPA_INVALID)
+ return -EEXIST;
+
+ /* Check the address is in a valid memslot */
+ idx = srcu_read_lock(&kvm->srcu);
+ if (kvm_is_error_hva(gfn_to_hva(kvm, ipa >> PAGE_SHIFT)))
+ ret = -EINVAL;
+ srcu_read_unlock(&kvm->srcu, idx);
+
+ if (!ret)
+ vcpu->arch.pv.base = ipa;
+
+ return ret;
+}
+
+int kvm_arm_pvlock_get_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ u64 __user *user = (u64 __user *)attr->addr;
+ u64 ipa;
+
+ if (attr->attr != KVM_ARM_VCPU_PVLOCK_IPA)
+ return -ENXIO;
+
+ ipa = vcpu->arch.pv.base;
+
+ if (put_user(ipa, user))
+ return -EFAULT;
+ return 0;
+}
+
+int kvm_arm_pvlock_has_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ switch (attr->attr) {
+ case KVM_ARM_VCPU_PVLOCK_IPA:
+ return 0;
+ }
+ return -ENXIO;
+}
\ No newline at end of file
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 0d5d4419139a..1fe3cce5c84a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1429,6 +1429,8 @@ enum kvm_device_type {
#define KVM_DEV_TYPE_XIVE KVM_DEV_TYPE_XIVE
KVM_DEV_TYPE_ARM_PV_TIME,
#define KVM_DEV_TYPE_ARM_PV_TIME KVM_DEV_TYPE_ARM_PV_TIME
+ KVM_DEV_TYPE_ARM_PV_LOCK,
+#define KVM_DEV_TYPE_ARM_PV_LOCK KVM_DEV_TYPE_ARM_PV_LOCK
KVM_DEV_TYPE_MAX,
};
--
2.25.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 4/6] KVM: arm64: Provide VCPU attributes for PV lock
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Allow user space to inform the KVM host where in the physical memory
map the paravirtualized lock structures should be located.
User space can set an attribute on the VCPU providing the IPA base
address of the PV lock structure for that VCPU. This must be
repeated for every VCPU in the VM.
The address is given in terms of the physical address visible to
the guest and must be 64 byte aligned. The guest will discover the
address via a hypercall.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/kvm_host.h | 7 ++++
arch/arm64/include/uapi/asm/kvm.h | 2 ++
arch/arm64/kvm/guest.c | 9 +++++
arch/arm64/kvm/pvlock.c | 57 +++++++++++++++++++++++++++++++
include/uapi/linux/kvm.h | 2 ++
5 files changed, 77 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 18303b30b7e9..86aeca8a4393 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -829,6 +829,13 @@ int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu,
int kvm_arm_pvtime_has_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr);
+int kvm_arm_pvlock_set_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+int kvm_arm_pvlock_get_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+int kvm_arm_pvlock_has_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+
extern unsigned int kvm_arm_vmid_bits;
int kvm_arm_vmid_alloc_init(void);
void kvm_arm_vmid_alloc_free(void);
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index bd05ece5c590..71010bacaaab 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -412,6 +412,8 @@ enum {
#define KVM_ARM_VCPU_TIMER_IRQ_PTIMER 1
#define KVM_ARM_VCPU_PVTIME_CTRL 2
#define KVM_ARM_VCPU_PVTIME_IPA 0
+#define KVM_ARM_VCPU_PVLOCK_CTRL 3
+#define KVM_ARM_VCPU_PVLOCK_IPA 0
/* KVM_IRQ_LINE irq field index values */
#define KVM_ARM_IRQ_VCPU2_SHIFT 28
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 2ff13a3f8479..7e765e3256ef 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -959,6 +959,9 @@ int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_set_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_set_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -982,6 +985,9 @@ int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_get_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_get_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -1005,6 +1011,9 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_has_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_has_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
diff --git a/arch/arm64/kvm/pvlock.c b/arch/arm64/kvm/pvlock.c
index 3eb35ab31481..b08a287a4811 100644
--- a/arch/arm64/kvm/pvlock.c
+++ b/arch/arm64/kvm/pvlock.c
@@ -41,3 +41,60 @@ void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted)
kvm_put_guest(kvm, base + offset, cpu_to_le64(preempted));
srcu_read_unlock(&kvm->srcu, idx);
}
+
+int kvm_arm_pvlock_set_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ u64 __user *user = (u64 __user *)attr->addr;
+ struct kvm *kvm = vcpu->kvm;
+ u64 ipa;
+ int ret = 0;
+ int idx;
+
+ if (attr->attr != KVM_ARM_VCPU_PVLOCK_IPA)
+ return -ENXIO;
+
+ if (get_user(ipa, user))
+ return -EFAULT;
+ if (!IS_ALIGNED(ipa, 64))
+ return -EINVAL;
+ if (vcpu->arch.pv.base != GPA_INVALID)
+ return -EEXIST;
+
+ /* Check the address is in a valid memslot */
+ idx = srcu_read_lock(&kvm->srcu);
+ if (kvm_is_error_hva(gfn_to_hva(kvm, ipa >> PAGE_SHIFT)))
+ ret = -EINVAL;
+ srcu_read_unlock(&kvm->srcu, idx);
+
+ if (!ret)
+ vcpu->arch.pv.base = ipa;
+
+ return ret;
+}
+
+int kvm_arm_pvlock_get_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ u64 __user *user = (u64 __user *)attr->addr;
+ u64 ipa;
+
+ if (attr->attr != KVM_ARM_VCPU_PVLOCK_IPA)
+ return -ENXIO;
+
+ ipa = vcpu->arch.pv.base;
+
+ if (put_user(ipa, user))
+ return -EFAULT;
+ return 0;
+}
+
+int kvm_arm_pvlock_has_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ switch (attr->attr) {
+ case KVM_ARM_VCPU_PVLOCK_IPA:
+ return 0;
+ }
+ return -ENXIO;
+}
\ No newline at end of file
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 0d5d4419139a..1fe3cce5c84a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1429,6 +1429,8 @@ enum kvm_device_type {
#define KVM_DEV_TYPE_XIVE KVM_DEV_TYPE_XIVE
KVM_DEV_TYPE_ARM_PV_TIME,
#define KVM_DEV_TYPE_ARM_PV_TIME KVM_DEV_TYPE_ARM_PV_TIME
+ KVM_DEV_TYPE_ARM_PV_LOCK,
+#define KVM_DEV_TYPE_ARM_PV_LOCK KVM_DEV_TYPE_ARM_PV_LOCK
KVM_DEV_TYPE_MAX,
};
--
2.25.1
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 4/6] KVM: arm64: Provide VCPU attributes for PV lock
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma, Usama Arif
Allow user space to inform the KVM host where in the physical memory
map the paravirtualized lock structures should be located.
User space can set an attribute on the VCPU providing the IPA base
address of the PV lock structure for that VCPU. This must be
repeated for every VCPU in the VM.
The address is given in terms of the physical address visible to
the guest and must be 64 byte aligned. The guest will discover the
address via a hypercall.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/kvm_host.h | 7 ++++
arch/arm64/include/uapi/asm/kvm.h | 2 ++
arch/arm64/kvm/guest.c | 9 +++++
arch/arm64/kvm/pvlock.c | 57 +++++++++++++++++++++++++++++++
include/uapi/linux/kvm.h | 2 ++
5 files changed, 77 insertions(+)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 18303b30b7e9..86aeca8a4393 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -829,6 +829,13 @@ int kvm_arm_pvtime_get_attr(struct kvm_vcpu *vcpu,
int kvm_arm_pvtime_has_attr(struct kvm_vcpu *vcpu,
struct kvm_device_attr *attr);
+int kvm_arm_pvlock_set_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+int kvm_arm_pvlock_get_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+int kvm_arm_pvlock_has_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr);
+
extern unsigned int kvm_arm_vmid_bits;
int kvm_arm_vmid_alloc_init(void);
void kvm_arm_vmid_alloc_free(void);
diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h
index bd05ece5c590..71010bacaaab 100644
--- a/arch/arm64/include/uapi/asm/kvm.h
+++ b/arch/arm64/include/uapi/asm/kvm.h
@@ -412,6 +412,8 @@ enum {
#define KVM_ARM_VCPU_TIMER_IRQ_PTIMER 1
#define KVM_ARM_VCPU_PVTIME_CTRL 2
#define KVM_ARM_VCPU_PVTIME_IPA 0
+#define KVM_ARM_VCPU_PVLOCK_CTRL 3
+#define KVM_ARM_VCPU_PVLOCK_IPA 0
/* KVM_IRQ_LINE irq field index values */
#define KVM_ARM_IRQ_VCPU2_SHIFT 28
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 2ff13a3f8479..7e765e3256ef 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -959,6 +959,9 @@ int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_set_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_set_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -982,6 +985,9 @@ int kvm_arm_vcpu_arch_get_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_get_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_get_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
@@ -1005,6 +1011,9 @@ int kvm_arm_vcpu_arch_has_attr(struct kvm_vcpu *vcpu,
case KVM_ARM_VCPU_PVTIME_CTRL:
ret = kvm_arm_pvtime_has_attr(vcpu, attr);
break;
+ case KVM_ARM_VCPU_PVLOCK_CTRL:
+ ret = kvm_arm_pvlock_has_attr(vcpu, attr);
+ break;
default:
ret = -ENXIO;
break;
diff --git a/arch/arm64/kvm/pvlock.c b/arch/arm64/kvm/pvlock.c
index 3eb35ab31481..b08a287a4811 100644
--- a/arch/arm64/kvm/pvlock.c
+++ b/arch/arm64/kvm/pvlock.c
@@ -41,3 +41,60 @@ void kvm_update_pvlock_preempted(struct kvm_vcpu *vcpu, u64 preempted)
kvm_put_guest(kvm, base + offset, cpu_to_le64(preempted));
srcu_read_unlock(&kvm->srcu, idx);
}
+
+int kvm_arm_pvlock_set_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ u64 __user *user = (u64 __user *)attr->addr;
+ struct kvm *kvm = vcpu->kvm;
+ u64 ipa;
+ int ret = 0;
+ int idx;
+
+ if (attr->attr != KVM_ARM_VCPU_PVLOCK_IPA)
+ return -ENXIO;
+
+ if (get_user(ipa, user))
+ return -EFAULT;
+ if (!IS_ALIGNED(ipa, 64))
+ return -EINVAL;
+ if (vcpu->arch.pv.base != GPA_INVALID)
+ return -EEXIST;
+
+ /* Check the address is in a valid memslot */
+ idx = srcu_read_lock(&kvm->srcu);
+ if (kvm_is_error_hva(gfn_to_hva(kvm, ipa >> PAGE_SHIFT)))
+ ret = -EINVAL;
+ srcu_read_unlock(&kvm->srcu, idx);
+
+ if (!ret)
+ vcpu->arch.pv.base = ipa;
+
+ return ret;
+}
+
+int kvm_arm_pvlock_get_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ u64 __user *user = (u64 __user *)attr->addr;
+ u64 ipa;
+
+ if (attr->attr != KVM_ARM_VCPU_PVLOCK_IPA)
+ return -ENXIO;
+
+ ipa = vcpu->arch.pv.base;
+
+ if (put_user(ipa, user))
+ return -EFAULT;
+ return 0;
+}
+
+int kvm_arm_pvlock_has_attr(struct kvm_vcpu *vcpu,
+ struct kvm_device_attr *attr)
+{
+ switch (attr->attr) {
+ case KVM_ARM_VCPU_PVLOCK_IPA:
+ return 0;
+ }
+ return -ENXIO;
+}
\ No newline at end of file
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 0d5d4419139a..1fe3cce5c84a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1429,6 +1429,8 @@ enum kvm_device_type {
#define KVM_DEV_TYPE_XIVE KVM_DEV_TYPE_XIVE
KVM_DEV_TYPE_ARM_PV_TIME,
#define KVM_DEV_TYPE_ARM_PV_TIME KVM_DEV_TYPE_ARM_PV_TIME
+ KVM_DEV_TYPE_ARM_PV_LOCK,
+#define KVM_DEV_TYPE_ARM_PV_LOCK KVM_DEV_TYPE_ARM_PV_LOCK
KVM_DEV_TYPE_MAX,
};
--
2.25.1
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 5/6] KVM: arm64: Support the VCPU preemption check
2022-11-02 16:13 ` Usama Arif
(?)
@ 2022-11-02 16:13 ` Usama Arif
-1 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Support the vcpu_is_preempted() functionality under KVM/arm64. This will
enhance lock performance on overcommitted hosts (more runnable VCPUs
than physical CPUs in the system) as doing busy waits for preempted
VCPUs will hurt system performance far worse than early yielding.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/paravirt.h | 2 +
arch/arm64/include/asm/spinlock.h | 16 +++-
arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
arch/arm64/kernel/setup.c | 3 +
include/linux/cpuhotplug.h | 1 +
5 files changed, 147 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
index 9aa193e0e8f2..4ccb4356c56b 100644
--- a/arch/arm64/include/asm/paravirt.h
+++ b/arch/arm64/include/asm/paravirt.h
@@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
}
int __init pv_time_init(void);
+int __init pv_lock_init(void);
#else
#define pv_time_init() do {} while (0)
+#define pv_lock_init() do {} while (0)
#endif // CONFIG_PARAVIRT
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index 0525c0b089ed..7023efa4de96 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -10,7 +10,20 @@
/* See include/linux/spinlock.h */
#define smp_mb__after_spinlock() smp_mb()
+#define vcpu_is_preempted vcpu_is_preempted
+
+#ifdef CONFIG_PARAVIRT
+#include <linux/static_call_types.h>
+
+bool dummy_vcpu_is_preempted(int cpu);
+DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
+static inline bool vcpu_is_preempted(int cpu)
+{
+ return static_call(pv_vcpu_is_preempted)(cpu);
+}
+
+#else
/*
* Changing this will break osq_lock() thanks to the call inside
* smp_cond_load_relaxed().
@@ -18,10 +31,11 @@
* See:
* https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
*/
-#define vcpu_is_preempted vcpu_is_preempted
static inline bool vcpu_is_preempted(int cpu)
{
return false;
}
+#endif /* CONFIG_PARAVIRT */
+
#endif /* __ASM_SPINLOCK_H */
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index 57c7c211f8c7..45bcca87bed7 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -22,6 +22,7 @@
#include <asm/paravirt.h>
#include <asm/pvclock-abi.h>
+#include <asm/pvlock-abi.h>
#include <asm/smp_plat.h>
struct static_key paravirt_steal_enabled;
@@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
struct pvclock_vcpu_stolen_time __rcu *kaddr;
};
+struct pv_lock_state_region {
+ struct pvlock_vcpu_state __rcu *kaddr;
+};
+
static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
+static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
static bool steal_acc = true;
static int __init parse_no_stealacc(char *arg)
@@ -178,3 +184,123 @@ int __init pv_time_init(void)
return 0;
}
+
+static bool native_vcpu_is_preempted(int cpu)
+{
+ return false;
+}
+
+DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
+
+static bool para_vcpu_is_preempted(int cpu)
+{
+ struct pv_lock_state_region *reg;
+ __le64 preempted_le;
+
+ reg = per_cpu_ptr(&lock_state_region, cpu);
+ if (!reg->kaddr) {
+ pr_warn_once("PV lock enabled but not configured for cpu %d\n",
+ cpu);
+ return false;
+ }
+
+ preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
+
+ return !!(preempted_le);
+}
+
+static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
+{
+ struct pv_lock_state_region *reg;
+
+ reg = this_cpu_ptr(&lock_state_region);
+ if (!reg->kaddr)
+ return 0;
+
+ memunmap(reg->kaddr);
+ memset(reg, 0, sizeof(*reg));
+
+ return 0;
+}
+
+static int init_pvlock_vcpu_state(unsigned int cpu)
+{
+ struct pv_lock_state_region *reg;
+ struct arm_smccc_res res;
+
+ reg = this_cpu_ptr(&lock_state_region);
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
+
+ if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
+ pr_warn("Failed to init PV lock data structure\n");
+ return -EINVAL;
+ }
+
+ reg->kaddr = memremap(res.a0,
+ sizeof(struct pvlock_vcpu_state),
+ MEMREMAP_WB);
+
+ if (!reg->kaddr) {
+ pr_warn("Failed to map PV lock data structure\n");
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static int kvm_arm_init_pvlock(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
+ "hypervisor/arm/pvlock:starting",
+ init_pvlock_vcpu_state,
+ pvlock_vcpu_state_dying_cpu);
+ if (ret < 0) {
+ pr_warn("PV-lock init failed\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static bool has_kvm_pvlock(void)
+{
+ struct arm_smccc_res res;
+
+ /* To detect the presence of PV lock support we require SMCCC 1.1+ */
+ if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
+ return false;
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
+ ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
+
+ if (res.a0 != SMCCC_RET_SUCCESS)
+ return false;
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
+ ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
+
+ return (res.a0 == SMCCC_RET_SUCCESS);
+}
+
+int __init pv_lock_init(void)
+{
+ int ret;
+
+ if (is_hyp_mode_available())
+ return 0;
+
+ if (!has_kvm_pvlock())
+ return 0;
+
+ ret = kvm_arm_init_pvlock();
+ if (ret)
+ return ret;
+
+ static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
+ pr_info("using PV-lock preempted\n");
+
+ return 0;
+}
\ No newline at end of file
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index fea3223704b6..05ca07ac5800 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -42,6 +42,7 @@
#include <asm/cpu_ops.h>
#include <asm/kasan.h>
#include <asm/numa.h>
+#include <asm/paravirt.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/smp_plat.h>
@@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
smp_init_cpus();
smp_build_mpidr_hash();
+ pv_lock_init();
+
/* Init percpu seeds for random tags after cpus are set up. */
kasan_init_sw_tags();
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f61447913db9..c0ee11855c73 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -192,6 +192,7 @@ enum cpuhp_state {
/* Must be the last timer callback */
CPUHP_AP_DUMMY_TIMER_STARTING,
CPUHP_AP_ARM_XEN_STARTING,
+ CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
CPUHP_AP_ARM_CORESIGHT_STARTING,
CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
CPUHP_AP_ARM64_ISNDEP_STARTING,
--
2.25.1
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 5/6] KVM: arm64: Support the VCPU preemption check
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
Support the vcpu_is_preempted() functionality under KVM/arm64. This will
enhance lock performance on overcommitted hosts (more runnable VCPUs
than physical CPUs in the system) as doing busy waits for preempted
VCPUs will hurt system performance far worse than early yielding.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/paravirt.h | 2 +
arch/arm64/include/asm/spinlock.h | 16 +++-
arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
arch/arm64/kernel/setup.c | 3 +
include/linux/cpuhotplug.h | 1 +
5 files changed, 147 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
index 9aa193e0e8f2..4ccb4356c56b 100644
--- a/arch/arm64/include/asm/paravirt.h
+++ b/arch/arm64/include/asm/paravirt.h
@@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
}
int __init pv_time_init(void);
+int __init pv_lock_init(void);
#else
#define pv_time_init() do {} while (0)
+#define pv_lock_init() do {} while (0)
#endif // CONFIG_PARAVIRT
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index 0525c0b089ed..7023efa4de96 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -10,7 +10,20 @@
/* See include/linux/spinlock.h */
#define smp_mb__after_spinlock() smp_mb()
+#define vcpu_is_preempted vcpu_is_preempted
+
+#ifdef CONFIG_PARAVIRT
+#include <linux/static_call_types.h>
+
+bool dummy_vcpu_is_preempted(int cpu);
+DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
+static inline bool vcpu_is_preempted(int cpu)
+{
+ return static_call(pv_vcpu_is_preempted)(cpu);
+}
+
+#else
/*
* Changing this will break osq_lock() thanks to the call inside
* smp_cond_load_relaxed().
@@ -18,10 +31,11 @@
* See:
* https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
*/
-#define vcpu_is_preempted vcpu_is_preempted
static inline bool vcpu_is_preempted(int cpu)
{
return false;
}
+#endif /* CONFIG_PARAVIRT */
+
#endif /* __ASM_SPINLOCK_H */
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index 57c7c211f8c7..45bcca87bed7 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -22,6 +22,7 @@
#include <asm/paravirt.h>
#include <asm/pvclock-abi.h>
+#include <asm/pvlock-abi.h>
#include <asm/smp_plat.h>
struct static_key paravirt_steal_enabled;
@@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
struct pvclock_vcpu_stolen_time __rcu *kaddr;
};
+struct pv_lock_state_region {
+ struct pvlock_vcpu_state __rcu *kaddr;
+};
+
static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
+static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
static bool steal_acc = true;
static int __init parse_no_stealacc(char *arg)
@@ -178,3 +184,123 @@ int __init pv_time_init(void)
return 0;
}
+
+static bool native_vcpu_is_preempted(int cpu)
+{
+ return false;
+}
+
+DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
+
+static bool para_vcpu_is_preempted(int cpu)
+{
+ struct pv_lock_state_region *reg;
+ __le64 preempted_le;
+
+ reg = per_cpu_ptr(&lock_state_region, cpu);
+ if (!reg->kaddr) {
+ pr_warn_once("PV lock enabled but not configured for cpu %d\n",
+ cpu);
+ return false;
+ }
+
+ preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
+
+ return !!(preempted_le);
+}
+
+static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
+{
+ struct pv_lock_state_region *reg;
+
+ reg = this_cpu_ptr(&lock_state_region);
+ if (!reg->kaddr)
+ return 0;
+
+ memunmap(reg->kaddr);
+ memset(reg, 0, sizeof(*reg));
+
+ return 0;
+}
+
+static int init_pvlock_vcpu_state(unsigned int cpu)
+{
+ struct pv_lock_state_region *reg;
+ struct arm_smccc_res res;
+
+ reg = this_cpu_ptr(&lock_state_region);
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
+
+ if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
+ pr_warn("Failed to init PV lock data structure\n");
+ return -EINVAL;
+ }
+
+ reg->kaddr = memremap(res.a0,
+ sizeof(struct pvlock_vcpu_state),
+ MEMREMAP_WB);
+
+ if (!reg->kaddr) {
+ pr_warn("Failed to map PV lock data structure\n");
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static int kvm_arm_init_pvlock(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
+ "hypervisor/arm/pvlock:starting",
+ init_pvlock_vcpu_state,
+ pvlock_vcpu_state_dying_cpu);
+ if (ret < 0) {
+ pr_warn("PV-lock init failed\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static bool has_kvm_pvlock(void)
+{
+ struct arm_smccc_res res;
+
+ /* To detect the presence of PV lock support we require SMCCC 1.1+ */
+ if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
+ return false;
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
+ ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
+
+ if (res.a0 != SMCCC_RET_SUCCESS)
+ return false;
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
+ ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
+
+ return (res.a0 == SMCCC_RET_SUCCESS);
+}
+
+int __init pv_lock_init(void)
+{
+ int ret;
+
+ if (is_hyp_mode_available())
+ return 0;
+
+ if (!has_kvm_pvlock())
+ return 0;
+
+ ret = kvm_arm_init_pvlock();
+ if (ret)
+ return ret;
+
+ static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
+ pr_info("using PV-lock preempted\n");
+
+ return 0;
+}
\ No newline at end of file
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index fea3223704b6..05ca07ac5800 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -42,6 +42,7 @@
#include <asm/cpu_ops.h>
#include <asm/kasan.h>
#include <asm/numa.h>
+#include <asm/paravirt.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/smp_plat.h>
@@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
smp_init_cpus();
smp_build_mpidr_hash();
+ pv_lock_init();
+
/* Init percpu seeds for random tags after cpus are set up. */
kasan_init_sw_tags();
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f61447913db9..c0ee11855c73 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -192,6 +192,7 @@ enum cpuhp_state {
/* Must be the last timer callback */
CPUHP_AP_DUMMY_TIMER_STARTING,
CPUHP_AP_ARM_XEN_STARTING,
+ CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
CPUHP_AP_ARM_CORESIGHT_STARTING,
CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
CPUHP_AP_ARM64_ISNDEP_STARTING,
--
2.25.1
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 5/6] KVM: arm64: Support the VCPU preemption check
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma, Usama Arif
Support the vcpu_is_preempted() functionality under KVM/arm64. This will
enhance lock performance on overcommitted hosts (more runnable VCPUs
than physical CPUs in the system) as doing busy waits for preempted
VCPUs will hurt system performance far worse than early yielding.
Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
arch/arm64/include/asm/paravirt.h | 2 +
arch/arm64/include/asm/spinlock.h | 16 +++-
arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
arch/arm64/kernel/setup.c | 3 +
include/linux/cpuhotplug.h | 1 +
5 files changed, 147 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
index 9aa193e0e8f2..4ccb4356c56b 100644
--- a/arch/arm64/include/asm/paravirt.h
+++ b/arch/arm64/include/asm/paravirt.h
@@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
}
int __init pv_time_init(void);
+int __init pv_lock_init(void);
#else
#define pv_time_init() do {} while (0)
+#define pv_lock_init() do {} while (0)
#endif // CONFIG_PARAVIRT
diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
index 0525c0b089ed..7023efa4de96 100644
--- a/arch/arm64/include/asm/spinlock.h
+++ b/arch/arm64/include/asm/spinlock.h
@@ -10,7 +10,20 @@
/* See include/linux/spinlock.h */
#define smp_mb__after_spinlock() smp_mb()
+#define vcpu_is_preempted vcpu_is_preempted
+
+#ifdef CONFIG_PARAVIRT
+#include <linux/static_call_types.h>
+
+bool dummy_vcpu_is_preempted(int cpu);
+DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
+static inline bool vcpu_is_preempted(int cpu)
+{
+ return static_call(pv_vcpu_is_preempted)(cpu);
+}
+
+#else
/*
* Changing this will break osq_lock() thanks to the call inside
* smp_cond_load_relaxed().
@@ -18,10 +31,11 @@
* See:
* https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
*/
-#define vcpu_is_preempted vcpu_is_preempted
static inline bool vcpu_is_preempted(int cpu)
{
return false;
}
+#endif /* CONFIG_PARAVIRT */
+
#endif /* __ASM_SPINLOCK_H */
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index 57c7c211f8c7..45bcca87bed7 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -22,6 +22,7 @@
#include <asm/paravirt.h>
#include <asm/pvclock-abi.h>
+#include <asm/pvlock-abi.h>
#include <asm/smp_plat.h>
struct static_key paravirt_steal_enabled;
@@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
struct pvclock_vcpu_stolen_time __rcu *kaddr;
};
+struct pv_lock_state_region {
+ struct pvlock_vcpu_state __rcu *kaddr;
+};
+
static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
+static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
static bool steal_acc = true;
static int __init parse_no_stealacc(char *arg)
@@ -178,3 +184,123 @@ int __init pv_time_init(void)
return 0;
}
+
+static bool native_vcpu_is_preempted(int cpu)
+{
+ return false;
+}
+
+DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
+
+static bool para_vcpu_is_preempted(int cpu)
+{
+ struct pv_lock_state_region *reg;
+ __le64 preempted_le;
+
+ reg = per_cpu_ptr(&lock_state_region, cpu);
+ if (!reg->kaddr) {
+ pr_warn_once("PV lock enabled but not configured for cpu %d\n",
+ cpu);
+ return false;
+ }
+
+ preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
+
+ return !!(preempted_le);
+}
+
+static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
+{
+ struct pv_lock_state_region *reg;
+
+ reg = this_cpu_ptr(&lock_state_region);
+ if (!reg->kaddr)
+ return 0;
+
+ memunmap(reg->kaddr);
+ memset(reg, 0, sizeof(*reg));
+
+ return 0;
+}
+
+static int init_pvlock_vcpu_state(unsigned int cpu)
+{
+ struct pv_lock_state_region *reg;
+ struct arm_smccc_res res;
+
+ reg = this_cpu_ptr(&lock_state_region);
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
+
+ if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
+ pr_warn("Failed to init PV lock data structure\n");
+ return -EINVAL;
+ }
+
+ reg->kaddr = memremap(res.a0,
+ sizeof(struct pvlock_vcpu_state),
+ MEMREMAP_WB);
+
+ if (!reg->kaddr) {
+ pr_warn("Failed to map PV lock data structure\n");
+ return -ENOMEM;
+ }
+
+ return 0;
+}
+
+static int kvm_arm_init_pvlock(void)
+{
+ int ret;
+
+ ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
+ "hypervisor/arm/pvlock:starting",
+ init_pvlock_vcpu_state,
+ pvlock_vcpu_state_dying_cpu);
+ if (ret < 0) {
+ pr_warn("PV-lock init failed\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static bool has_kvm_pvlock(void)
+{
+ struct arm_smccc_res res;
+
+ /* To detect the presence of PV lock support we require SMCCC 1.1+ */
+ if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
+ return false;
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
+ ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
+
+ if (res.a0 != SMCCC_RET_SUCCESS)
+ return false;
+
+ arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
+ ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
+
+ return (res.a0 == SMCCC_RET_SUCCESS);
+}
+
+int __init pv_lock_init(void)
+{
+ int ret;
+
+ if (is_hyp_mode_available())
+ return 0;
+
+ if (!has_kvm_pvlock())
+ return 0;
+
+ ret = kvm_arm_init_pvlock();
+ if (ret)
+ return ret;
+
+ static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
+ pr_info("using PV-lock preempted\n");
+
+ return 0;
+}
\ No newline at end of file
diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
index fea3223704b6..05ca07ac5800 100644
--- a/arch/arm64/kernel/setup.c
+++ b/arch/arm64/kernel/setup.c
@@ -42,6 +42,7 @@
#include <asm/cpu_ops.h>
#include <asm/kasan.h>
#include <asm/numa.h>
+#include <asm/paravirt.h>
#include <asm/sections.h>
#include <asm/setup.h>
#include <asm/smp_plat.h>
@@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
smp_init_cpus();
smp_build_mpidr_hash();
+ pv_lock_init();
+
/* Init percpu seeds for random tags after cpus are set up. */
kasan_init_sw_tags();
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f61447913db9..c0ee11855c73 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -192,6 +192,7 @@ enum cpuhp_state {
/* Must be the last timer callback */
CPUHP_AP_DUMMY_TIMER_STARTING,
CPUHP_AP_ARM_XEN_STARTING,
+ CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
CPUHP_AP_ARM_CORESIGHT_STARTING,
CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
CPUHP_AP_ARM64_ISNDEP_STARTING,
--
2.25.1
_______________________________________________
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kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 6/6] KVM: selftests: add tests for PV time specific hypercalls
2022-11-02 16:13 ` Usama Arif
(?)
@ 2022-11-02 16:13 ` Usama Arif
-1 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
These are vendor specific hypercalls.
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
tools/testing/selftests/kvm/aarch64/hypercalls.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/tools/testing/selftests/kvm/aarch64/hypercalls.c b/tools/testing/selftests/kvm/aarch64/hypercalls.c
index a39da3fe4952..743ee6cb97d8 100644
--- a/tools/testing/selftests/kvm/aarch64/hypercalls.c
+++ b/tools/testing/selftests/kvm/aarch64/hypercalls.c
@@ -79,6 +79,8 @@ static const struct test_hvc_info hvc_info[] = {
ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID),
TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, 0),
TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, KVM_PTP_VIRT_COUNTER),
+ TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_HV_PV_LOCK_FEATURES),
+ TEST_HVC_INFO(ARM_SMCCC_HV_PV_LOCK_FEATURES, ARM_SMCCC_HV_PV_LOCK_PREEMPTED),
};
/* Feed false hypercall info to test the KVM behavior */
--
2.25.1
_______________________________________________
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linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 6/6] KVM: selftests: add tests for PV time specific hypercalls
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal, Usama Arif
These are vendor specific hypercalls.
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
tools/testing/selftests/kvm/aarch64/hypercalls.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/tools/testing/selftests/kvm/aarch64/hypercalls.c b/tools/testing/selftests/kvm/aarch64/hypercalls.c
index a39da3fe4952..743ee6cb97d8 100644
--- a/tools/testing/selftests/kvm/aarch64/hypercalls.c
+++ b/tools/testing/selftests/kvm/aarch64/hypercalls.c
@@ -79,6 +79,8 @@ static const struct test_hvc_info hvc_info[] = {
ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID),
TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, 0),
TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, KVM_PTP_VIRT_COUNTER),
+ TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_HV_PV_LOCK_FEATURES),
+ TEST_HVC_INFO(ARM_SMCCC_HV_PV_LOCK_FEATURES, ARM_SMCCC_HV_PV_LOCK_PREEMPTED),
};
/* Feed false hypercall info to test the KVM behavior */
--
2.25.1
^ permalink raw reply related [flat|nested] 36+ messages in thread
* [RFC 6/6] KVM: selftests: add tests for PV time specific hypercalls
@ 2022-11-02 16:13 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-02 16:13 UTC (permalink / raw)
To: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma, Usama Arif
These are vendor specific hypercalls.
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
---
tools/testing/selftests/kvm/aarch64/hypercalls.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/tools/testing/selftests/kvm/aarch64/hypercalls.c b/tools/testing/selftests/kvm/aarch64/hypercalls.c
index a39da3fe4952..743ee6cb97d8 100644
--- a/tools/testing/selftests/kvm/aarch64/hypercalls.c
+++ b/tools/testing/selftests/kvm/aarch64/hypercalls.c
@@ -79,6 +79,8 @@ static const struct test_hvc_info hvc_info[] = {
ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID),
TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, 0),
TEST_HVC_INFO(ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID, KVM_PTP_VIRT_COUNTER),
+ TEST_HVC_INFO(ARM_SMCCC_ARCH_FEATURES_FUNC_ID, ARM_SMCCC_HV_PV_LOCK_FEATURES),
+ TEST_HVC_INFO(ARM_SMCCC_HV_PV_LOCK_FEATURES, ARM_SMCCC_HV_PV_LOCK_PREEMPTED),
};
/* Feed false hypercall info to test the KVM behavior */
--
2.25.1
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 36+ messages in thread
* Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
2022-11-02 16:13 ` Usama Arif
(?)
@ 2022-11-03 3:50 ` Bagas Sanjaya
-1 siblings, 0 replies; 36+ messages in thread
From: Bagas Sanjaya @ 2022-11-03 3:50 UTC (permalink / raw)
To: Usama Arif
Cc: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland, fam.zheng, liangma, punit.agrawal
[-- Attachment #1: Type: text/plain, Size: 6115 bytes --]
On Wed, Nov 02, 2022 at 04:13:35PM +0000, Usama Arif wrote:
> + ============= ======== ==========
> + Function ID: (uint32) 0xC6000020
> + PV_call_id: (uint32) The function to query for support.
> + Currently only PV_LOCK_PREEMPTED is supported.
> + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
> + PV-lock feature is supported by the hypervisor.
> + ============= ======== ==========
> +
> +PV_LOCK_PREEMPTED
> + ============= ======== ==========
> + Function ID: (uint32) 0xC6000021
> + Return value: (int64) IPA of the pv lock data structure for this
> + VCPU. On failure:
> + NOT_SUPPORTED (-1)
> + ============= ======== ==========
> +
You need to fix up these tables above:
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
index 766aeef50b2d31..940a1cb221bc90 100644
--- a/Documentation/virt/kvm/arm/pvlock.rst
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -15,21 +15,23 @@ The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
ARCH_FEATURES mechanism before calling it.
PV_LOCK_FEATURES
- ============= ======== ==========
+
+ ============= ======== =================================================
Function ID: (uint32) 0xC6000020
PV_call_id: (uint32) The function to query for support.
Currently only PV_LOCK_PREEMPTED is supported.
Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
PV-lock feature is supported by the hypervisor.
- ============= ======== ==========
+ ============= ======== =================================================
PV_LOCK_PREEMPTED
- ============= ======== ==========
+
+ ============= ======== ==========================================
Function ID: (uint32) 0xC6000021
Return value: (int64) IPA of the pv lock data structure for this
VCPU. On failure:
NOT_SUPPORTED (-1)
- ============= ======== ==========
+ ============= ======== ==========================================
The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
memory with inner and outer write back caching attributes, in the inner
The similar fixup should also be made to the tables in
Documentation/virt/kvm/arm/pvtime.rst, though.
> +The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
> +memory with inner and outer write back caching attributes, in the inner
> +shareable domain.
> +
> +PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
> +
> +PV lock state
> +-------------
> +
> +The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
> +
> ++-----------+-------------+-------------+---------------------------------+
> +| Field | Byte Length | Byte Offset | Description |
> ++===========+=============+=============+=================================+
> +| preempted | 8 | 0 | Indicate if the VCPU that owns |
> +| | | | this struct is running or not. |
> +| | | | Non-zero values mean the VCPU |
> +| | | | has been preempted. Zero means |
> +| | | | the VCPU is not preempted. |
> ++-----------+-------------+-------------+---------------------------------+
> +
> +The preempted field will be updated to 1 by the hypervisor prior to scheduling
> +a VCPU. When the VCPU is scheduled out, the preempted field will be updated
> +to 0 by the hypervisor.
> +
> +The structure will be present within a reserved region of the normal memory
> +given to the guest. The guest should not attempt to write into this memory.
> +There is a structure per VCPU of the guest.
> +
> +For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
> +section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
Use reST labels for cross-referencing to the documentation section:
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
index 940a1cb221bc90..4e9d09b76ef033 100644
--- a/Documentation/virt/kvm/arm/pvlock.rst
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -62,5 +62,5 @@ The structure will be present within a reserved region of the normal memory
given to the guest. The guest should not attempt to write into this memory.
There is a structure per VCPU of the guest.
-For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
-section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
+For the user space interface see :ref:`KVM_VCPU_TSC_CTRL in Generic vcpu
+interface documentation <kvm-vcpu-tsc-ctrl>`.
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 223ac2fe62f01f..6532f61073a39c 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -194,6 +194,8 @@ base address must be 64 byte aligned and exist within a valid guest memory
region. See Documentation/virt/kvm/arm/pvtime.rst for more information
including the layout of the stolen time structure.
+.. _kvm-vcpu-tsc-ctrl:
+
4. GROUP: KVM_VCPU_TSC_CTRL
===========================
Also, you need to add the documentation to table of contents (index):
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
index e8484843215808..b8499dc00a6a96 100644
--- a/Documentation/virt/kvm/arm/index.rst
+++ b/Documentation/virt/kvm/arm/index.rst
@@ -10,4 +10,5 @@ ARM
hyp-abi
hypercalls
pvtime
+ pvlock
ptp_kvm
Thanks.
--
An old man doll... just what I always wanted! - Clara
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]
^ permalink raw reply related [flat|nested] 36+ messages in thread
* Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
@ 2022-11-03 3:50 ` Bagas Sanjaya
0 siblings, 0 replies; 36+ messages in thread
From: Bagas Sanjaya @ 2022-11-03 3:50 UTC (permalink / raw)
To: Usama Arif
Cc: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland, fam.zheng, liangma, punit.agrawal
[-- Attachment #1.1: Type: text/plain, Size: 6115 bytes --]
On Wed, Nov 02, 2022 at 04:13:35PM +0000, Usama Arif wrote:
> + ============= ======== ==========
> + Function ID: (uint32) 0xC6000020
> + PV_call_id: (uint32) The function to query for support.
> + Currently only PV_LOCK_PREEMPTED is supported.
> + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
> + PV-lock feature is supported by the hypervisor.
> + ============= ======== ==========
> +
> +PV_LOCK_PREEMPTED
> + ============= ======== ==========
> + Function ID: (uint32) 0xC6000021
> + Return value: (int64) IPA of the pv lock data structure for this
> + VCPU. On failure:
> + NOT_SUPPORTED (-1)
> + ============= ======== ==========
> +
You need to fix up these tables above:
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
index 766aeef50b2d31..940a1cb221bc90 100644
--- a/Documentation/virt/kvm/arm/pvlock.rst
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -15,21 +15,23 @@ The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
ARCH_FEATURES mechanism before calling it.
PV_LOCK_FEATURES
- ============= ======== ==========
+
+ ============= ======== =================================================
Function ID: (uint32) 0xC6000020
PV_call_id: (uint32) The function to query for support.
Currently only PV_LOCK_PREEMPTED is supported.
Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
PV-lock feature is supported by the hypervisor.
- ============= ======== ==========
+ ============= ======== =================================================
PV_LOCK_PREEMPTED
- ============= ======== ==========
+
+ ============= ======== ==========================================
Function ID: (uint32) 0xC6000021
Return value: (int64) IPA of the pv lock data structure for this
VCPU. On failure:
NOT_SUPPORTED (-1)
- ============= ======== ==========
+ ============= ======== ==========================================
The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
memory with inner and outer write back caching attributes, in the inner
The similar fixup should also be made to the tables in
Documentation/virt/kvm/arm/pvtime.rst, though.
> +The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
> +memory with inner and outer write back caching attributes, in the inner
> +shareable domain.
> +
> +PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
> +
> +PV lock state
> +-------------
> +
> +The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
> +
> ++-----------+-------------+-------------+---------------------------------+
> +| Field | Byte Length | Byte Offset | Description |
> ++===========+=============+=============+=================================+
> +| preempted | 8 | 0 | Indicate if the VCPU that owns |
> +| | | | this struct is running or not. |
> +| | | | Non-zero values mean the VCPU |
> +| | | | has been preempted. Zero means |
> +| | | | the VCPU is not preempted. |
> ++-----------+-------------+-------------+---------------------------------+
> +
> +The preempted field will be updated to 1 by the hypervisor prior to scheduling
> +a VCPU. When the VCPU is scheduled out, the preempted field will be updated
> +to 0 by the hypervisor.
> +
> +The structure will be present within a reserved region of the normal memory
> +given to the guest. The guest should not attempt to write into this memory.
> +There is a structure per VCPU of the guest.
> +
> +For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
> +section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
Use reST labels for cross-referencing to the documentation section:
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
index 940a1cb221bc90..4e9d09b76ef033 100644
--- a/Documentation/virt/kvm/arm/pvlock.rst
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -62,5 +62,5 @@ The structure will be present within a reserved region of the normal memory
given to the guest. The guest should not attempt to write into this memory.
There is a structure per VCPU of the guest.
-For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
-section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
+For the user space interface see :ref:`KVM_VCPU_TSC_CTRL in Generic vcpu
+interface documentation <kvm-vcpu-tsc-ctrl>`.
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 223ac2fe62f01f..6532f61073a39c 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -194,6 +194,8 @@ base address must be 64 byte aligned and exist within a valid guest memory
region. See Documentation/virt/kvm/arm/pvtime.rst for more information
including the layout of the stolen time structure.
+.. _kvm-vcpu-tsc-ctrl:
+
4. GROUP: KVM_VCPU_TSC_CTRL
===========================
Also, you need to add the documentation to table of contents (index):
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
index e8484843215808..b8499dc00a6a96 100644
--- a/Documentation/virt/kvm/arm/index.rst
+++ b/Documentation/virt/kvm/arm/index.rst
@@ -10,4 +10,5 @@ ARM
hyp-abi
hypercalls
pvtime
+ pvlock
ptp_kvm
Thanks.
--
An old man doll... just what I always wanted! - Clara
[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]
[-- Attachment #2: Type: text/plain, Size: 176 bytes --]
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply related [flat|nested] 36+ messages in thread
* Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
@ 2022-11-03 3:50 ` Bagas Sanjaya
0 siblings, 0 replies; 36+ messages in thread
From: Bagas Sanjaya @ 2022-11-03 3:50 UTC (permalink / raw)
To: Usama Arif
Cc: kvm, linux-doc, catalin.marinas, linux-kernel, virtualization,
fam.zheng, maz, punit.agrawal, linux, liangma, steven.price,
will, kvmarm, linux-arm-kernel
[-- Attachment #1.1: Type: text/plain, Size: 6115 bytes --]
On Wed, Nov 02, 2022 at 04:13:35PM +0000, Usama Arif wrote:
> + ============= ======== ==========
> + Function ID: (uint32) 0xC6000020
> + PV_call_id: (uint32) The function to query for support.
> + Currently only PV_LOCK_PREEMPTED is supported.
> + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
> + PV-lock feature is supported by the hypervisor.
> + ============= ======== ==========
> +
> +PV_LOCK_PREEMPTED
> + ============= ======== ==========
> + Function ID: (uint32) 0xC6000021
> + Return value: (int64) IPA of the pv lock data structure for this
> + VCPU. On failure:
> + NOT_SUPPORTED (-1)
> + ============= ======== ==========
> +
You need to fix up these tables above:
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
index 766aeef50b2d31..940a1cb221bc90 100644
--- a/Documentation/virt/kvm/arm/pvlock.rst
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -15,21 +15,23 @@ The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
ARCH_FEATURES mechanism before calling it.
PV_LOCK_FEATURES
- ============= ======== ==========
+
+ ============= ======== =================================================
Function ID: (uint32) 0xC6000020
PV_call_id: (uint32) The function to query for support.
Currently only PV_LOCK_PREEMPTED is supported.
Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
PV-lock feature is supported by the hypervisor.
- ============= ======== ==========
+ ============= ======== =================================================
PV_LOCK_PREEMPTED
- ============= ======== ==========
+
+ ============= ======== ==========================================
Function ID: (uint32) 0xC6000021
Return value: (int64) IPA of the pv lock data structure for this
VCPU. On failure:
NOT_SUPPORTED (-1)
- ============= ======== ==========
+ ============= ======== ==========================================
The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
memory with inner and outer write back caching attributes, in the inner
The similar fixup should also be made to the tables in
Documentation/virt/kvm/arm/pvtime.rst, though.
> +The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
> +memory with inner and outer write back caching attributes, in the inner
> +shareable domain.
> +
> +PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
> +
> +PV lock state
> +-------------
> +
> +The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
> +
> ++-----------+-------------+-------------+---------------------------------+
> +| Field | Byte Length | Byte Offset | Description |
> ++===========+=============+=============+=================================+
> +| preempted | 8 | 0 | Indicate if the VCPU that owns |
> +| | | | this struct is running or not. |
> +| | | | Non-zero values mean the VCPU |
> +| | | | has been preempted. Zero means |
> +| | | | the VCPU is not preempted. |
> ++-----------+-------------+-------------+---------------------------------+
> +
> +The preempted field will be updated to 1 by the hypervisor prior to scheduling
> +a VCPU. When the VCPU is scheduled out, the preempted field will be updated
> +to 0 by the hypervisor.
> +
> +The structure will be present within a reserved region of the normal memory
> +given to the guest. The guest should not attempt to write into this memory.
> +There is a structure per VCPU of the guest.
> +
> +For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
> +section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
Use reST labels for cross-referencing to the documentation section:
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
index 940a1cb221bc90..4e9d09b76ef033 100644
--- a/Documentation/virt/kvm/arm/pvlock.rst
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -62,5 +62,5 @@ The structure will be present within a reserved region of the normal memory
given to the guest. The guest should not attempt to write into this memory.
There is a structure per VCPU of the guest.
-For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
-section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
+For the user space interface see :ref:`KVM_VCPU_TSC_CTRL in Generic vcpu
+interface documentation <kvm-vcpu-tsc-ctrl>`.
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 223ac2fe62f01f..6532f61073a39c 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -194,6 +194,8 @@ base address must be 64 byte aligned and exist within a valid guest memory
region. See Documentation/virt/kvm/arm/pvtime.rst for more information
including the layout of the stolen time structure.
+.. _kvm-vcpu-tsc-ctrl:
+
4. GROUP: KVM_VCPU_TSC_CTRL
===========================
Also, you need to add the documentation to table of contents (index):
---- >8 ----
diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
index e8484843215808..b8499dc00a6a96 100644
--- a/Documentation/virt/kvm/arm/index.rst
+++ b/Documentation/virt/kvm/arm/index.rst
@@ -10,4 +10,5 @@ ARM
hyp-abi
hypercalls
pvtime
+ pvlock
ptp_kvm
Thanks.
--
An old man doll... just what I always wanted! - Clara
[-- Attachment #1.2: signature.asc --]
[-- Type: application/pgp-signature, Size: 228 bytes --]
[-- Attachment #2: Type: text/plain, Size: 151 bytes --]
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
2022-11-03 3:50 ` Bagas Sanjaya
(?)
@ 2022-11-03 13:15 ` Usama Arif
-1 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-03 13:15 UTC (permalink / raw)
To: Bagas Sanjaya
Cc: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland, fam.zheng, liangma, punit.agrawal
Hi,
Thanks for the review. I will include the changes in the next version I
send for pvlock. I have sent a patch to fix pvtime here
https://lore.kernel.org/all/20221103131210.3603385-1-usama.arif@bytedance.com/.
Usama
On 03/11/2022 03:50, Bagas Sanjaya wrote:
> On Wed, Nov 02, 2022 at 04:13:35PM +0000, Usama Arif wrote:
>> + ============= ======== ==========
>> + Function ID: (uint32) 0xC6000020
>> + PV_call_id: (uint32) The function to query for support.
>> + Currently only PV_LOCK_PREEMPTED is supported.
>> + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
>> + PV-lock feature is supported by the hypervisor.
>> + ============= ======== ==========
>> +
>> +PV_LOCK_PREEMPTED
>> + ============= ======== ==========
>> + Function ID: (uint32) 0xC6000021
>> + Return value: (int64) IPA of the pv lock data structure for this
>> + VCPU. On failure:
>> + NOT_SUPPORTED (-1)
>> + ============= ======== ==========
>> +
>
> You need to fix up these tables above:
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
> index 766aeef50b2d31..940a1cb221bc90 100644
> --- a/Documentation/virt/kvm/arm/pvlock.rst
> +++ b/Documentation/virt/kvm/arm/pvlock.rst
> @@ -15,21 +15,23 @@ The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
> ARCH_FEATURES mechanism before calling it.
>
> PV_LOCK_FEATURES
> - ============= ======== ==========
> +
> + ============= ======== =================================================
> Function ID: (uint32) 0xC6000020
> PV_call_id: (uint32) The function to query for support.
> Currently only PV_LOCK_PREEMPTED is supported.
> Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
> PV-lock feature is supported by the hypervisor.
> - ============= ======== ==========
> + ============= ======== =================================================
>
> PV_LOCK_PREEMPTED
> - ============= ======== ==========
> +
> + ============= ======== ==========================================
> Function ID: (uint32) 0xC6000021
> Return value: (int64) IPA of the pv lock data structure for this
> VCPU. On failure:
> NOT_SUPPORTED (-1)
> - ============= ======== ==========
> + ============= ======== ==========================================
>
> The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
> memory with inner and outer write back caching attributes, in the inner
>
> The similar fixup should also be made to the tables in
> Documentation/virt/kvm/arm/pvtime.rst, though.
>
>> +The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
>> +memory with inner and outer write back caching attributes, in the inner
>> +shareable domain.
>> +
>> +PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
>> +
>> +PV lock state
>> +-------------
>> +
>> +The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
>> +
>> ++-----------+-------------+-------------+---------------------------------+
>> +| Field | Byte Length | Byte Offset | Description |
>> ++===========+=============+=============+=================================+
>> +| preempted | 8 | 0 | Indicate if the VCPU that owns |
>> +| | | | this struct is running or not. |
>> +| | | | Non-zero values mean the VCPU |
>> +| | | | has been preempted. Zero means |
>> +| | | | the VCPU is not preempted. |
>> ++-----------+-------------+-------------+---------------------------------+
>> +
>> +The preempted field will be updated to 1 by the hypervisor prior to scheduling
>> +a VCPU. When the VCPU is scheduled out, the preempted field will be updated
>> +to 0 by the hypervisor.
>> +
>> +The structure will be present within a reserved region of the normal memory
>> +given to the guest. The guest should not attempt to write into this memory.
>> +There is a structure per VCPU of the guest.
>> +
>> +For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
>> +section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
>
> Use reST labels for cross-referencing to the documentation section:
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
> index 940a1cb221bc90..4e9d09b76ef033 100644
> --- a/Documentation/virt/kvm/arm/pvlock.rst
> +++ b/Documentation/virt/kvm/arm/pvlock.rst
> @@ -62,5 +62,5 @@ The structure will be present within a reserved region of the normal memory
> given to the guest. The guest should not attempt to write into this memory.
> There is a structure per VCPU of the guest.
>
> -For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
> -section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
> +For the user space interface see :ref:`KVM_VCPU_TSC_CTRL in Generic vcpu
> +interface documentation <kvm-vcpu-tsc-ctrl>`.
> diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
> index 223ac2fe62f01f..6532f61073a39c 100644
> --- a/Documentation/virt/kvm/devices/vcpu.rst
> +++ b/Documentation/virt/kvm/devices/vcpu.rst
> @@ -194,6 +194,8 @@ base address must be 64 byte aligned and exist within a valid guest memory
> region. See Documentation/virt/kvm/arm/pvtime.rst for more information
> including the layout of the stolen time structure.
>
> +.. _kvm-vcpu-tsc-ctrl:
> +
> 4. GROUP: KVM_VCPU_TSC_CTRL
> ===========================
>
>
> Also, you need to add the documentation to table of contents (index):
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
> index e8484843215808..b8499dc00a6a96 100644
> --- a/Documentation/virt/kvm/arm/index.rst
> +++ b/Documentation/virt/kvm/arm/index.rst
> @@ -10,4 +10,5 @@ ARM
> hyp-abi
> hypercalls
> pvtime
> + pvlock
> ptp_kvm
>
> Thanks.
>
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
@ 2022-11-03 13:15 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-03 13:15 UTC (permalink / raw)
To: Bagas Sanjaya
Cc: kvm, linux-doc, catalin.marinas, linux-kernel, virtualization,
fam.zheng, maz, punit.agrawal, linux, liangma, steven.price,
will, kvmarm, linux-arm-kernel
Hi,
Thanks for the review. I will include the changes in the next version I
send for pvlock. I have sent a patch to fix pvtime here
https://lore.kernel.org/all/20221103131210.3603385-1-usama.arif@bytedance.com/.
Usama
On 03/11/2022 03:50, Bagas Sanjaya wrote:
> On Wed, Nov 02, 2022 at 04:13:35PM +0000, Usama Arif wrote:
>> + ============= ======== ==========
>> + Function ID: (uint32) 0xC6000020
>> + PV_call_id: (uint32) The function to query for support.
>> + Currently only PV_LOCK_PREEMPTED is supported.
>> + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
>> + PV-lock feature is supported by the hypervisor.
>> + ============= ======== ==========
>> +
>> +PV_LOCK_PREEMPTED
>> + ============= ======== ==========
>> + Function ID: (uint32) 0xC6000021
>> + Return value: (int64) IPA of the pv lock data structure for this
>> + VCPU. On failure:
>> + NOT_SUPPORTED (-1)
>> + ============= ======== ==========
>> +
>
> You need to fix up these tables above:
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
> index 766aeef50b2d31..940a1cb221bc90 100644
> --- a/Documentation/virt/kvm/arm/pvlock.rst
> +++ b/Documentation/virt/kvm/arm/pvlock.rst
> @@ -15,21 +15,23 @@ The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
> ARCH_FEATURES mechanism before calling it.
>
> PV_LOCK_FEATURES
> - ============= ======== ==========
> +
> + ============= ======== =================================================
> Function ID: (uint32) 0xC6000020
> PV_call_id: (uint32) The function to query for support.
> Currently only PV_LOCK_PREEMPTED is supported.
> Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
> PV-lock feature is supported by the hypervisor.
> - ============= ======== ==========
> + ============= ======== =================================================
>
> PV_LOCK_PREEMPTED
> - ============= ======== ==========
> +
> + ============= ======== ==========================================
> Function ID: (uint32) 0xC6000021
> Return value: (int64) IPA of the pv lock data structure for this
> VCPU. On failure:
> NOT_SUPPORTED (-1)
> - ============= ======== ==========
> + ============= ======== ==========================================
>
> The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
> memory with inner and outer write back caching attributes, in the inner
>
> The similar fixup should also be made to the tables in
> Documentation/virt/kvm/arm/pvtime.rst, though.
>
>> +The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
>> +memory with inner and outer write back caching attributes, in the inner
>> +shareable domain.
>> +
>> +PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
>> +
>> +PV lock state
>> +-------------
>> +
>> +The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
>> +
>> ++-----------+-------------+-------------+---------------------------------+
>> +| Field | Byte Length | Byte Offset | Description |
>> ++===========+=============+=============+=================================+
>> +| preempted | 8 | 0 | Indicate if the VCPU that owns |
>> +| | | | this struct is running or not. |
>> +| | | | Non-zero values mean the VCPU |
>> +| | | | has been preempted. Zero means |
>> +| | | | the VCPU is not preempted. |
>> ++-----------+-------------+-------------+---------------------------------+
>> +
>> +The preempted field will be updated to 1 by the hypervisor prior to scheduling
>> +a VCPU. When the VCPU is scheduled out, the preempted field will be updated
>> +to 0 by the hypervisor.
>> +
>> +The structure will be present within a reserved region of the normal memory
>> +given to the guest. The guest should not attempt to write into this memory.
>> +There is a structure per VCPU of the guest.
>> +
>> +For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
>> +section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
>
> Use reST labels for cross-referencing to the documentation section:
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
> index 940a1cb221bc90..4e9d09b76ef033 100644
> --- a/Documentation/virt/kvm/arm/pvlock.rst
> +++ b/Documentation/virt/kvm/arm/pvlock.rst
> @@ -62,5 +62,5 @@ The structure will be present within a reserved region of the normal memory
> given to the guest. The guest should not attempt to write into this memory.
> There is a structure per VCPU of the guest.
>
> -For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
> -section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
> +For the user space interface see :ref:`KVM_VCPU_TSC_CTRL in Generic vcpu
> +interface documentation <kvm-vcpu-tsc-ctrl>`.
> diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
> index 223ac2fe62f01f..6532f61073a39c 100644
> --- a/Documentation/virt/kvm/devices/vcpu.rst
> +++ b/Documentation/virt/kvm/devices/vcpu.rst
> @@ -194,6 +194,8 @@ base address must be 64 byte aligned and exist within a valid guest memory
> region. See Documentation/virt/kvm/arm/pvtime.rst for more information
> including the layout of the stolen time structure.
>
> +.. _kvm-vcpu-tsc-ctrl:
> +
> 4. GROUP: KVM_VCPU_TSC_CTRL
> ===========================
>
>
> Also, you need to add the documentation to table of contents (index):
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
> index e8484843215808..b8499dc00a6a96 100644
> --- a/Documentation/virt/kvm/arm/index.rst
> +++ b/Documentation/virt/kvm/arm/index.rst
> @@ -10,4 +10,5 @@ ARM
> hyp-abi
> hypercalls
> pvtime
> + pvlock
> ptp_kvm
>
> Thanks.
>
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
@ 2022-11-03 13:15 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-03 13:15 UTC (permalink / raw)
To: Bagas Sanjaya
Cc: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland, fam.zheng, liangma, punit.agrawal
Hi,
Thanks for the review. I will include the changes in the next version I
send for pvlock. I have sent a patch to fix pvtime here
https://lore.kernel.org/all/20221103131210.3603385-1-usama.arif@bytedance.com/.
Usama
On 03/11/2022 03:50, Bagas Sanjaya wrote:
> On Wed, Nov 02, 2022 at 04:13:35PM +0000, Usama Arif wrote:
>> + ============= ======== ==========
>> + Function ID: (uint32) 0xC6000020
>> + PV_call_id: (uint32) The function to query for support.
>> + Currently only PV_LOCK_PREEMPTED is supported.
>> + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
>> + PV-lock feature is supported by the hypervisor.
>> + ============= ======== ==========
>> +
>> +PV_LOCK_PREEMPTED
>> + ============= ======== ==========
>> + Function ID: (uint32) 0xC6000021
>> + Return value: (int64) IPA of the pv lock data structure for this
>> + VCPU. On failure:
>> + NOT_SUPPORTED (-1)
>> + ============= ======== ==========
>> +
>
> You need to fix up these tables above:
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
> index 766aeef50b2d31..940a1cb221bc90 100644
> --- a/Documentation/virt/kvm/arm/pvlock.rst
> +++ b/Documentation/virt/kvm/arm/pvlock.rst
> @@ -15,21 +15,23 @@ The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
> ARCH_FEATURES mechanism before calling it.
>
> PV_LOCK_FEATURES
> - ============= ======== ==========
> +
> + ============= ======== =================================================
> Function ID: (uint32) 0xC6000020
> PV_call_id: (uint32) The function to query for support.
> Currently only PV_LOCK_PREEMPTED is supported.
> Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
> PV-lock feature is supported by the hypervisor.
> - ============= ======== ==========
> + ============= ======== =================================================
>
> PV_LOCK_PREEMPTED
> - ============= ======== ==========
> +
> + ============= ======== ==========================================
> Function ID: (uint32) 0xC6000021
> Return value: (int64) IPA of the pv lock data structure for this
> VCPU. On failure:
> NOT_SUPPORTED (-1)
> - ============= ======== ==========
> + ============= ======== ==========================================
>
> The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
> memory with inner and outer write back caching attributes, in the inner
>
> The similar fixup should also be made to the tables in
> Documentation/virt/kvm/arm/pvtime.rst, though.
>
>> +The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
>> +memory with inner and outer write back caching attributes, in the inner
>> +shareable domain.
>> +
>> +PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
>> +
>> +PV lock state
>> +-------------
>> +
>> +The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
>> +
>> ++-----------+-------------+-------------+---------------------------------+
>> +| Field | Byte Length | Byte Offset | Description |
>> ++===========+=============+=============+=================================+
>> +| preempted | 8 | 0 | Indicate if the VCPU that owns |
>> +| | | | this struct is running or not. |
>> +| | | | Non-zero values mean the VCPU |
>> +| | | | has been preempted. Zero means |
>> +| | | | the VCPU is not preempted. |
>> ++-----------+-------------+-------------+---------------------------------+
>> +
>> +The preempted field will be updated to 1 by the hypervisor prior to scheduling
>> +a VCPU. When the VCPU is scheduled out, the preempted field will be updated
>> +to 0 by the hypervisor.
>> +
>> +The structure will be present within a reserved region of the normal memory
>> +given to the guest. The guest should not attempt to write into this memory.
>> +There is a structure per VCPU of the guest.
>> +
>> +For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
>> +section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
>
> Use reST labels for cross-referencing to the documentation section:
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
> index 940a1cb221bc90..4e9d09b76ef033 100644
> --- a/Documentation/virt/kvm/arm/pvlock.rst
> +++ b/Documentation/virt/kvm/arm/pvlock.rst
> @@ -62,5 +62,5 @@ The structure will be present within a reserved region of the normal memory
> given to the guest. The guest should not attempt to write into this memory.
> There is a structure per VCPU of the guest.
>
> -For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
> -section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
> +For the user space interface see :ref:`KVM_VCPU_TSC_CTRL in Generic vcpu
> +interface documentation <kvm-vcpu-tsc-ctrl>`.
> diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
> index 223ac2fe62f01f..6532f61073a39c 100644
> --- a/Documentation/virt/kvm/devices/vcpu.rst
> +++ b/Documentation/virt/kvm/devices/vcpu.rst
> @@ -194,6 +194,8 @@ base address must be 64 byte aligned and exist within a valid guest memory
> region. See Documentation/virt/kvm/arm/pvtime.rst for more information
> including the layout of the stolen time structure.
>
> +.. _kvm-vcpu-tsc-ctrl:
> +
> 4. GROUP: KVM_VCPU_TSC_CTRL
> ===========================
>
>
> Also, you need to add the documentation to table of contents (index):
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
> index e8484843215808..b8499dc00a6a96 100644
> --- a/Documentation/virt/kvm/arm/index.rst
> +++ b/Documentation/virt/kvm/arm/index.rst
> @@ -10,4 +10,5 @@ ARM
> hyp-abi
> hypercalls
> pvtime
> + pvlock
> ptp_kvm
>
> Thanks.
>
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [RFC 5/6] KVM: arm64: Support the VCPU preemption check
2022-11-02 16:13 ` Usama Arif
(?)
@ 2022-11-03 13:25 ` Steven Price
-1 siblings, 0 replies; 36+ messages in thread
From: Steven Price @ 2022-11-03 13:25 UTC (permalink / raw)
To: Usama Arif, linux-kernel, linux-arm-kernel, kvmarm, kvm,
linux-doc, virtualization, linux, yezengruan, catalin.marinas,
will, maz, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal
On 02/11/2022 16:13, Usama Arif wrote:
> Support the vcpu_is_preempted() functionality under KVM/arm64. This will
> enhance lock performance on overcommitted hosts (more runnable VCPUs
> than physical CPUs in the system) as doing busy waits for preempted
> VCPUs will hurt system performance far worse than early yielding.
>
> Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
> ---
> arch/arm64/include/asm/paravirt.h | 2 +
> arch/arm64/include/asm/spinlock.h | 16 +++-
> arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
> arch/arm64/kernel/setup.c | 3 +
> include/linux/cpuhotplug.h | 1 +
> 5 files changed, 147 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
> index 9aa193e0e8f2..4ccb4356c56b 100644
> --- a/arch/arm64/include/asm/paravirt.h
> +++ b/arch/arm64/include/asm/paravirt.h
> @@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
> }
>
> int __init pv_time_init(void);
> +int __init pv_lock_init(void);
>
> #else
>
> #define pv_time_init() do {} while (0)
> +#define pv_lock_init() do {} while (0)
>
> #endif // CONFIG_PARAVIRT
>
> diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
> index 0525c0b089ed..7023efa4de96 100644
> --- a/arch/arm64/include/asm/spinlock.h
> +++ b/arch/arm64/include/asm/spinlock.h
> @@ -10,7 +10,20 @@
>
> /* See include/linux/spinlock.h */
> #define smp_mb__after_spinlock() smp_mb()
> +#define vcpu_is_preempted vcpu_is_preempted
> +
> +#ifdef CONFIG_PARAVIRT
> +#include <linux/static_call_types.h>
> +
> +bool dummy_vcpu_is_preempted(int cpu);
>
> +DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
> +static inline bool vcpu_is_preempted(int cpu)
> +{
> + return static_call(pv_vcpu_is_preempted)(cpu);
> +}
> +
> +#else
> /*
> * Changing this will break osq_lock() thanks to the call inside
> * smp_cond_load_relaxed().
> @@ -18,10 +31,11 @@
> * See:
> * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
> */
> -#define vcpu_is_preempted vcpu_is_preempted
> static inline bool vcpu_is_preempted(int cpu)
> {
> return false;
> }
>
> +#endif /* CONFIG_PARAVIRT */
> +
> #endif /* __ASM_SPINLOCK_H */
> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
> index 57c7c211f8c7..45bcca87bed7 100644
> --- a/arch/arm64/kernel/paravirt.c
> +++ b/arch/arm64/kernel/paravirt.c
> @@ -22,6 +22,7 @@
>
> #include <asm/paravirt.h>
> #include <asm/pvclock-abi.h>
> +#include <asm/pvlock-abi.h>
> #include <asm/smp_plat.h>
>
> struct static_key paravirt_steal_enabled;
> @@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
> struct pvclock_vcpu_stolen_time __rcu *kaddr;
> };
>
> +struct pv_lock_state_region {
> + struct pvlock_vcpu_state __rcu *kaddr;
> +};
> +
> static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
> +static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
>
> static bool steal_acc = true;
> static int __init parse_no_stealacc(char *arg)
> @@ -178,3 +184,123 @@ int __init pv_time_init(void)
>
> return 0;
> }
> +
> +static bool native_vcpu_is_preempted(int cpu)
> +{
> + return false;
> +}
> +
> +DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
> +
> +static bool para_vcpu_is_preempted(int cpu)
> +{
> + struct pv_lock_state_region *reg;
> + __le64 preempted_le;
> +
> + reg = per_cpu_ptr(&lock_state_region, cpu);
> + if (!reg->kaddr) {
> + pr_warn_once("PV lock enabled but not configured for cpu %d\n",
> + cpu);
> + return false;
> + }
> +
> + preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
> +
> + return !!(preempted_le);
> +}
> +
> +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
> +{
> + struct pv_lock_state_region *reg;
> +
> + reg = this_cpu_ptr(&lock_state_region);
> + if (!reg->kaddr)
> + return 0;
> +
> + memunmap(reg->kaddr);
> + memset(reg, 0, sizeof(*reg));
> +
> + return 0;
> +}
> +
> +static int init_pvlock_vcpu_state(unsigned int cpu)
> +{
> + struct pv_lock_state_region *reg;
> + struct arm_smccc_res res;
> +
> + reg = this_cpu_ptr(&lock_state_region);
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
> +
> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
> + pr_warn("Failed to init PV lock data structure\n");
> + return -EINVAL;
> + }
> +
> + reg->kaddr = memremap(res.a0,
> + sizeof(struct pvlock_vcpu_state),
> + MEMREMAP_WB);
> +
> + if (!reg->kaddr) {
> + pr_warn("Failed to map PV lock data structure\n");
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static int kvm_arm_init_pvlock(void)
> +{
> + int ret;
> +
> + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
> + "hypervisor/arm/pvlock:starting",
> + init_pvlock_vcpu_state,
> + pvlock_vcpu_state_dying_cpu);
> + if (ret < 0) {
> + pr_warn("PV-lock init failed\n");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static bool has_kvm_pvlock(void)
> +{
> + struct arm_smccc_res res;
> +
> + /* To detect the presence of PV lock support we require SMCCC 1.1+ */
> + if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
> + return false;
This is unnecessary as arm_smccc_1_1_invoke() will return failure if
there's no conduit (or pre-SMCCC 1.1). I suspect this was a copy/paste
from has_pv_steal_clock() which also has the unnecessary check (patch
welcome ;) ).
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
> + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
Since this is a 'OWNER_VENDOR_HYP' call this should really be preceded
by a check that we're running under the expected hypervisor. See e.g.
kvm_init_hyp_services().
Of course for KVM we already have a (different) discovery mechanism and
this could be included as a ARM_SMCCC_KVM_FUNC_xxx feature. This
has_kvm_pvlock() function would then simply be:
static bool has_kvm_pvlock(void)
{
return kvm_arm_hyp_service_available(ARM_SMCC_KVM_FUNC_PVLOCK);
}
Steve
> +
> + if (res.a0 != SMCCC_RET_SUCCESS)
> + return false;
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
> + ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
> +
> + return (res.a0 == SMCCC_RET_SUCCESS);
> +}
> +
> +int __init pv_lock_init(void)
> +{
> + int ret;
> +
> + if (is_hyp_mode_available())
> + return 0;
> +
> + if (!has_kvm_pvlock())
> + return 0;
> +
> + ret = kvm_arm_init_pvlock();
> + if (ret)
> + return ret;
> +
> + static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
> + pr_info("using PV-lock preempted\n");
> +
> + return 0;
> +}
> \ No newline at end of file
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index fea3223704b6..05ca07ac5800 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -42,6 +42,7 @@
> #include <asm/cpu_ops.h>
> #include <asm/kasan.h>
> #include <asm/numa.h>
> +#include <asm/paravirt.h>
> #include <asm/sections.h>
> #include <asm/setup.h>
> #include <asm/smp_plat.h>
> @@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
> smp_init_cpus();
> smp_build_mpidr_hash();
>
> + pv_lock_init();
> +
> /* Init percpu seeds for random tags after cpus are set up. */
> kasan_init_sw_tags();
>
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index f61447913db9..c0ee11855c73 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -192,6 +192,7 @@ enum cpuhp_state {
> /* Must be the last timer callback */
> CPUHP_AP_DUMMY_TIMER_STARTING,
> CPUHP_AP_ARM_XEN_STARTING,
> + CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
> CPUHP_AP_ARM_CORESIGHT_STARTING,
> CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
> CPUHP_AP_ARM64_ISNDEP_STARTING,
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [RFC 5/6] KVM: arm64: Support the VCPU preemption check
@ 2022-11-03 13:25 ` Steven Price
0 siblings, 0 replies; 36+ messages in thread
From: Steven Price @ 2022-11-03 13:25 UTC (permalink / raw)
To: Usama Arif, linux-kernel, linux-arm-kernel, kvmarm, kvm,
linux-doc, virtualization, linux, yezengruan, catalin.marinas,
will, maz, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma
On 02/11/2022 16:13, Usama Arif wrote:
> Support the vcpu_is_preempted() functionality under KVM/arm64. This will
> enhance lock performance on overcommitted hosts (more runnable VCPUs
> than physical CPUs in the system) as doing busy waits for preempted
> VCPUs will hurt system performance far worse than early yielding.
>
> Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
> ---
> arch/arm64/include/asm/paravirt.h | 2 +
> arch/arm64/include/asm/spinlock.h | 16 +++-
> arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
> arch/arm64/kernel/setup.c | 3 +
> include/linux/cpuhotplug.h | 1 +
> 5 files changed, 147 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
> index 9aa193e0e8f2..4ccb4356c56b 100644
> --- a/arch/arm64/include/asm/paravirt.h
> +++ b/arch/arm64/include/asm/paravirt.h
> @@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
> }
>
> int __init pv_time_init(void);
> +int __init pv_lock_init(void);
>
> #else
>
> #define pv_time_init() do {} while (0)
> +#define pv_lock_init() do {} while (0)
>
> #endif // CONFIG_PARAVIRT
>
> diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
> index 0525c0b089ed..7023efa4de96 100644
> --- a/arch/arm64/include/asm/spinlock.h
> +++ b/arch/arm64/include/asm/spinlock.h
> @@ -10,7 +10,20 @@
>
> /* See include/linux/spinlock.h */
> #define smp_mb__after_spinlock() smp_mb()
> +#define vcpu_is_preempted vcpu_is_preempted
> +
> +#ifdef CONFIG_PARAVIRT
> +#include <linux/static_call_types.h>
> +
> +bool dummy_vcpu_is_preempted(int cpu);
>
> +DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
> +static inline bool vcpu_is_preempted(int cpu)
> +{
> + return static_call(pv_vcpu_is_preempted)(cpu);
> +}
> +
> +#else
> /*
> * Changing this will break osq_lock() thanks to the call inside
> * smp_cond_load_relaxed().
> @@ -18,10 +31,11 @@
> * See:
> * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
> */
> -#define vcpu_is_preempted vcpu_is_preempted
> static inline bool vcpu_is_preempted(int cpu)
> {
> return false;
> }
>
> +#endif /* CONFIG_PARAVIRT */
> +
> #endif /* __ASM_SPINLOCK_H */
> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
> index 57c7c211f8c7..45bcca87bed7 100644
> --- a/arch/arm64/kernel/paravirt.c
> +++ b/arch/arm64/kernel/paravirt.c
> @@ -22,6 +22,7 @@
>
> #include <asm/paravirt.h>
> #include <asm/pvclock-abi.h>
> +#include <asm/pvlock-abi.h>
> #include <asm/smp_plat.h>
>
> struct static_key paravirt_steal_enabled;
> @@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
> struct pvclock_vcpu_stolen_time __rcu *kaddr;
> };
>
> +struct pv_lock_state_region {
> + struct pvlock_vcpu_state __rcu *kaddr;
> +};
> +
> static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
> +static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
>
> static bool steal_acc = true;
> static int __init parse_no_stealacc(char *arg)
> @@ -178,3 +184,123 @@ int __init pv_time_init(void)
>
> return 0;
> }
> +
> +static bool native_vcpu_is_preempted(int cpu)
> +{
> + return false;
> +}
> +
> +DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
> +
> +static bool para_vcpu_is_preempted(int cpu)
> +{
> + struct pv_lock_state_region *reg;
> + __le64 preempted_le;
> +
> + reg = per_cpu_ptr(&lock_state_region, cpu);
> + if (!reg->kaddr) {
> + pr_warn_once("PV lock enabled but not configured for cpu %d\n",
> + cpu);
> + return false;
> + }
> +
> + preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
> +
> + return !!(preempted_le);
> +}
> +
> +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
> +{
> + struct pv_lock_state_region *reg;
> +
> + reg = this_cpu_ptr(&lock_state_region);
> + if (!reg->kaddr)
> + return 0;
> +
> + memunmap(reg->kaddr);
> + memset(reg, 0, sizeof(*reg));
> +
> + return 0;
> +}
> +
> +static int init_pvlock_vcpu_state(unsigned int cpu)
> +{
> + struct pv_lock_state_region *reg;
> + struct arm_smccc_res res;
> +
> + reg = this_cpu_ptr(&lock_state_region);
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
> +
> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
> + pr_warn("Failed to init PV lock data structure\n");
> + return -EINVAL;
> + }
> +
> + reg->kaddr = memremap(res.a0,
> + sizeof(struct pvlock_vcpu_state),
> + MEMREMAP_WB);
> +
> + if (!reg->kaddr) {
> + pr_warn("Failed to map PV lock data structure\n");
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static int kvm_arm_init_pvlock(void)
> +{
> + int ret;
> +
> + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
> + "hypervisor/arm/pvlock:starting",
> + init_pvlock_vcpu_state,
> + pvlock_vcpu_state_dying_cpu);
> + if (ret < 0) {
> + pr_warn("PV-lock init failed\n");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static bool has_kvm_pvlock(void)
> +{
> + struct arm_smccc_res res;
> +
> + /* To detect the presence of PV lock support we require SMCCC 1.1+ */
> + if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
> + return false;
This is unnecessary as arm_smccc_1_1_invoke() will return failure if
there's no conduit (or pre-SMCCC 1.1). I suspect this was a copy/paste
from has_pv_steal_clock() which also has the unnecessary check (patch
welcome ;) ).
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
> + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
Since this is a 'OWNER_VENDOR_HYP' call this should really be preceded
by a check that we're running under the expected hypervisor. See e.g.
kvm_init_hyp_services().
Of course for KVM we already have a (different) discovery mechanism and
this could be included as a ARM_SMCCC_KVM_FUNC_xxx feature. This
has_kvm_pvlock() function would then simply be:
static bool has_kvm_pvlock(void)
{
return kvm_arm_hyp_service_available(ARM_SMCC_KVM_FUNC_PVLOCK);
}
Steve
> +
> + if (res.a0 != SMCCC_RET_SUCCESS)
> + return false;
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
> + ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
> +
> + return (res.a0 == SMCCC_RET_SUCCESS);
> +}
> +
> +int __init pv_lock_init(void)
> +{
> + int ret;
> +
> + if (is_hyp_mode_available())
> + return 0;
> +
> + if (!has_kvm_pvlock())
> + return 0;
> +
> + ret = kvm_arm_init_pvlock();
> + if (ret)
> + return ret;
> +
> + static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
> + pr_info("using PV-lock preempted\n");
> +
> + return 0;
> +}
> \ No newline at end of file
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index fea3223704b6..05ca07ac5800 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -42,6 +42,7 @@
> #include <asm/cpu_ops.h>
> #include <asm/kasan.h>
> #include <asm/numa.h>
> +#include <asm/paravirt.h>
> #include <asm/sections.h>
> #include <asm/setup.h>
> #include <asm/smp_plat.h>
> @@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
> smp_init_cpus();
> smp_build_mpidr_hash();
>
> + pv_lock_init();
> +
> /* Init percpu seeds for random tags after cpus are set up. */
> kasan_init_sw_tags();
>
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index f61447913db9..c0ee11855c73 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -192,6 +192,7 @@ enum cpuhp_state {
> /* Must be the last timer callback */
> CPUHP_AP_DUMMY_TIMER_STARTING,
> CPUHP_AP_ARM_XEN_STARTING,
> + CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
> CPUHP_AP_ARM_CORESIGHT_STARTING,
> CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
> CPUHP_AP_ARM64_ISNDEP_STARTING,
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^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [RFC 5/6] KVM: arm64: Support the VCPU preemption check
@ 2022-11-03 13:25 ` Steven Price
0 siblings, 0 replies; 36+ messages in thread
From: Steven Price @ 2022-11-03 13:25 UTC (permalink / raw)
To: Usama Arif, linux-kernel, linux-arm-kernel, kvmarm, kvm,
linux-doc, virtualization, linux, yezengruan, catalin.marinas,
will, maz, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal
On 02/11/2022 16:13, Usama Arif wrote:
> Support the vcpu_is_preempted() functionality under KVM/arm64. This will
> enhance lock performance on overcommitted hosts (more runnable VCPUs
> than physical CPUs in the system) as doing busy waits for preempted
> VCPUs will hurt system performance far worse than early yielding.
>
> Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
> ---
> arch/arm64/include/asm/paravirt.h | 2 +
> arch/arm64/include/asm/spinlock.h | 16 +++-
> arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
> arch/arm64/kernel/setup.c | 3 +
> include/linux/cpuhotplug.h | 1 +
> 5 files changed, 147 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
> index 9aa193e0e8f2..4ccb4356c56b 100644
> --- a/arch/arm64/include/asm/paravirt.h
> +++ b/arch/arm64/include/asm/paravirt.h
> @@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
> }
>
> int __init pv_time_init(void);
> +int __init pv_lock_init(void);
>
> #else
>
> #define pv_time_init() do {} while (0)
> +#define pv_lock_init() do {} while (0)
>
> #endif // CONFIG_PARAVIRT
>
> diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
> index 0525c0b089ed..7023efa4de96 100644
> --- a/arch/arm64/include/asm/spinlock.h
> +++ b/arch/arm64/include/asm/spinlock.h
> @@ -10,7 +10,20 @@
>
> /* See include/linux/spinlock.h */
> #define smp_mb__after_spinlock() smp_mb()
> +#define vcpu_is_preempted vcpu_is_preempted
> +
> +#ifdef CONFIG_PARAVIRT
> +#include <linux/static_call_types.h>
> +
> +bool dummy_vcpu_is_preempted(int cpu);
>
> +DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
> +static inline bool vcpu_is_preempted(int cpu)
> +{
> + return static_call(pv_vcpu_is_preempted)(cpu);
> +}
> +
> +#else
> /*
> * Changing this will break osq_lock() thanks to the call inside
> * smp_cond_load_relaxed().
> @@ -18,10 +31,11 @@
> * See:
> * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
> */
> -#define vcpu_is_preempted vcpu_is_preempted
> static inline bool vcpu_is_preempted(int cpu)
> {
> return false;
> }
>
> +#endif /* CONFIG_PARAVIRT */
> +
> #endif /* __ASM_SPINLOCK_H */
> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
> index 57c7c211f8c7..45bcca87bed7 100644
> --- a/arch/arm64/kernel/paravirt.c
> +++ b/arch/arm64/kernel/paravirt.c
> @@ -22,6 +22,7 @@
>
> #include <asm/paravirt.h>
> #include <asm/pvclock-abi.h>
> +#include <asm/pvlock-abi.h>
> #include <asm/smp_plat.h>
>
> struct static_key paravirt_steal_enabled;
> @@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
> struct pvclock_vcpu_stolen_time __rcu *kaddr;
> };
>
> +struct pv_lock_state_region {
> + struct pvlock_vcpu_state __rcu *kaddr;
> +};
> +
> static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
> +static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
>
> static bool steal_acc = true;
> static int __init parse_no_stealacc(char *arg)
> @@ -178,3 +184,123 @@ int __init pv_time_init(void)
>
> return 0;
> }
> +
> +static bool native_vcpu_is_preempted(int cpu)
> +{
> + return false;
> +}
> +
> +DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
> +
> +static bool para_vcpu_is_preempted(int cpu)
> +{
> + struct pv_lock_state_region *reg;
> + __le64 preempted_le;
> +
> + reg = per_cpu_ptr(&lock_state_region, cpu);
> + if (!reg->kaddr) {
> + pr_warn_once("PV lock enabled but not configured for cpu %d\n",
> + cpu);
> + return false;
> + }
> +
> + preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
> +
> + return !!(preempted_le);
> +}
> +
> +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
> +{
> + struct pv_lock_state_region *reg;
> +
> + reg = this_cpu_ptr(&lock_state_region);
> + if (!reg->kaddr)
> + return 0;
> +
> + memunmap(reg->kaddr);
> + memset(reg, 0, sizeof(*reg));
> +
> + return 0;
> +}
> +
> +static int init_pvlock_vcpu_state(unsigned int cpu)
> +{
> + struct pv_lock_state_region *reg;
> + struct arm_smccc_res res;
> +
> + reg = this_cpu_ptr(&lock_state_region);
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
> +
> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
> + pr_warn("Failed to init PV lock data structure\n");
> + return -EINVAL;
> + }
> +
> + reg->kaddr = memremap(res.a0,
> + sizeof(struct pvlock_vcpu_state),
> + MEMREMAP_WB);
> +
> + if (!reg->kaddr) {
> + pr_warn("Failed to map PV lock data structure\n");
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +static int kvm_arm_init_pvlock(void)
> +{
> + int ret;
> +
> + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
> + "hypervisor/arm/pvlock:starting",
> + init_pvlock_vcpu_state,
> + pvlock_vcpu_state_dying_cpu);
> + if (ret < 0) {
> + pr_warn("PV-lock init failed\n");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static bool has_kvm_pvlock(void)
> +{
> + struct arm_smccc_res res;
> +
> + /* To detect the presence of PV lock support we require SMCCC 1.1+ */
> + if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
> + return false;
This is unnecessary as arm_smccc_1_1_invoke() will return failure if
there's no conduit (or pre-SMCCC 1.1). I suspect this was a copy/paste
from has_pv_steal_clock() which also has the unnecessary check (patch
welcome ;) ).
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
> + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
Since this is a 'OWNER_VENDOR_HYP' call this should really be preceded
by a check that we're running under the expected hypervisor. See e.g.
kvm_init_hyp_services().
Of course for KVM we already have a (different) discovery mechanism and
this could be included as a ARM_SMCCC_KVM_FUNC_xxx feature. This
has_kvm_pvlock() function would then simply be:
static bool has_kvm_pvlock(void)
{
return kvm_arm_hyp_service_available(ARM_SMCC_KVM_FUNC_PVLOCK);
}
Steve
> +
> + if (res.a0 != SMCCC_RET_SUCCESS)
> + return false;
> +
> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
> + ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
> +
> + return (res.a0 == SMCCC_RET_SUCCESS);
> +}
> +
> +int __init pv_lock_init(void)
> +{
> + int ret;
> +
> + if (is_hyp_mode_available())
> + return 0;
> +
> + if (!has_kvm_pvlock())
> + return 0;
> +
> + ret = kvm_arm_init_pvlock();
> + if (ret)
> + return ret;
> +
> + static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
> + pr_info("using PV-lock preempted\n");
> +
> + return 0;
> +}
> \ No newline at end of file
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index fea3223704b6..05ca07ac5800 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -42,6 +42,7 @@
> #include <asm/cpu_ops.h>
> #include <asm/kasan.h>
> #include <asm/numa.h>
> +#include <asm/paravirt.h>
> #include <asm/sections.h>
> #include <asm/setup.h>
> #include <asm/smp_plat.h>
> @@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
> smp_init_cpus();
> smp_build_mpidr_hash();
>
> + pv_lock_init();
> +
> /* Init percpu seeds for random tags after cpus are set up. */
> kasan_init_sw_tags();
>
> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
> index f61447913db9..c0ee11855c73 100644
> --- a/include/linux/cpuhotplug.h
> +++ b/include/linux/cpuhotplug.h
> @@ -192,6 +192,7 @@ enum cpuhp_state {
> /* Must be the last timer callback */
> CPUHP_AP_DUMMY_TIMER_STARTING,
> CPUHP_AP_ARM_XEN_STARTING,
> + CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
> CPUHP_AP_ARM_CORESIGHT_STARTING,
> CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
> CPUHP_AP_ARM64_ISNDEP_STARTING,
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
2022-11-03 13:15 ` Usama Arif
(?)
@ 2022-11-03 13:56 ` Bagas Sanjaya
-1 siblings, 0 replies; 36+ messages in thread
From: Bagas Sanjaya @ 2022-11-03 13:56 UTC (permalink / raw)
To: Usama Arif
Cc: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland, fam.zheng, liangma, punit.agrawal
On 11/3/22 20:15, Usama Arif wrote:
> Hi,
>
> Thanks for the review. I will include the changes in the next version I send for pvlock. I have sent a patch to fix pvtime here https://lore.kernel.org/all/20221103131210.3603385-1-usama.arif@bytedance.com/.
>
Please please please *DON'T* top-post; reply inline instead.
--
An old man doll... just what I always wanted! - Clara
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
@ 2022-11-03 13:56 ` Bagas Sanjaya
0 siblings, 0 replies; 36+ messages in thread
From: Bagas Sanjaya @ 2022-11-03 13:56 UTC (permalink / raw)
To: Usama Arif
Cc: linux-kernel, linux-arm-kernel, kvmarm, kvm, linux-doc,
virtualization, linux, yezengruan, catalin.marinas, will, maz,
steven.price, mark.rutland, fam.zheng, liangma, punit.agrawal
On 11/3/22 20:15, Usama Arif wrote:
> Hi,
>
> Thanks for the review. I will include the changes in the next version I send for pvlock. I have sent a patch to fix pvtime here https://lore.kernel.org/all/20221103131210.3603385-1-usama.arif@bytedance.com/.
>
Please please please *DON'T* top-post; reply inline instead.
--
An old man doll... just what I always wanted! - Clara
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
@ 2022-11-03 13:56 ` Bagas Sanjaya
0 siblings, 0 replies; 36+ messages in thread
From: Bagas Sanjaya @ 2022-11-03 13:56 UTC (permalink / raw)
To: Usama Arif
Cc: kvm, linux-doc, catalin.marinas, linux-kernel, virtualization,
fam.zheng, maz, punit.agrawal, linux, liangma, steven.price,
will, kvmarm, linux-arm-kernel
On 11/3/22 20:15, Usama Arif wrote:
> Hi,
>
> Thanks for the review. I will include the changes in the next version I send for pvlock. I have sent a patch to fix pvtime here https://lore.kernel.org/all/20221103131210.3603385-1-usama.arif@bytedance.com/.
>
Please please please *DON'T* top-post; reply inline instead.
--
An old man doll... just what I always wanted! - Clara
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 5/6] KVM: arm64: Support the VCPU preemption check
2022-11-03 13:25 ` Steven Price
(?)
@ 2022-11-04 6:24 ` Usama Arif
-1 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-04 6:24 UTC (permalink / raw)
To: Steven Price, linux-kernel, linux-arm-kernel, kvmarm, kvm,
linux-doc, virtualization, linux, yezengruan, catalin.marinas,
will, maz, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal
On 03/11/2022 13:25, Steven Price wrote:
> On 02/11/2022 16:13, Usama Arif wrote:
>> Support the vcpu_is_preempted() functionality under KVM/arm64. This will
>> enhance lock performance on overcommitted hosts (more runnable VCPUs
>> than physical CPUs in the system) as doing busy waits for preempted
>> VCPUs will hurt system performance far worse than early yielding.
>>
>> Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
>> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
>> ---
>> arch/arm64/include/asm/paravirt.h | 2 +
>> arch/arm64/include/asm/spinlock.h | 16 +++-
>> arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
>> arch/arm64/kernel/setup.c | 3 +
>> include/linux/cpuhotplug.h | 1 +
>> 5 files changed, 147 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
>> index 9aa193e0e8f2..4ccb4356c56b 100644
>> --- a/arch/arm64/include/asm/paravirt.h
>> +++ b/arch/arm64/include/asm/paravirt.h
>> @@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
>> }
>>
>> int __init pv_time_init(void);
>> +int __init pv_lock_init(void);
>>
>> #else
>>
>> #define pv_time_init() do {} while (0)
>> +#define pv_lock_init() do {} while (0)
>>
>> #endif // CONFIG_PARAVIRT
>>
>> diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
>> index 0525c0b089ed..7023efa4de96 100644
>> --- a/arch/arm64/include/asm/spinlock.h
>> +++ b/arch/arm64/include/asm/spinlock.h
>> @@ -10,7 +10,20 @@
>>
>> /* See include/linux/spinlock.h */
>> #define smp_mb__after_spinlock() smp_mb()
>> +#define vcpu_is_preempted vcpu_is_preempted
>> +
>> +#ifdef CONFIG_PARAVIRT
>> +#include <linux/static_call_types.h>
>> +
>> +bool dummy_vcpu_is_preempted(int cpu);
>>
>> +DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
>> +static inline bool vcpu_is_preempted(int cpu)
>> +{
>> + return static_call(pv_vcpu_is_preempted)(cpu);
>> +}
>> +
>> +#else
>> /*
>> * Changing this will break osq_lock() thanks to the call inside
>> * smp_cond_load_relaxed().
>> @@ -18,10 +31,11 @@
>> * See:
>> * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
>> */
>> -#define vcpu_is_preempted vcpu_is_preempted
>> static inline bool vcpu_is_preempted(int cpu)
>> {
>> return false;
>> }
>>
>> +#endif /* CONFIG_PARAVIRT */
>> +
>> #endif /* __ASM_SPINLOCK_H */
>> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
>> index 57c7c211f8c7..45bcca87bed7 100644
>> --- a/arch/arm64/kernel/paravirt.c
>> +++ b/arch/arm64/kernel/paravirt.c
>> @@ -22,6 +22,7 @@
>>
>> #include <asm/paravirt.h>
>> #include <asm/pvclock-abi.h>
>> +#include <asm/pvlock-abi.h>
>> #include <asm/smp_plat.h>
>>
>> struct static_key paravirt_steal_enabled;
>> @@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
>> struct pvclock_vcpu_stolen_time __rcu *kaddr;
>> };
>>
>> +struct pv_lock_state_region {
>> + struct pvlock_vcpu_state __rcu *kaddr;
>> +};
>> +
>> static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
>> +static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
>>
>> static bool steal_acc = true;
>> static int __init parse_no_stealacc(char *arg)
>> @@ -178,3 +184,123 @@ int __init pv_time_init(void)
>>
>> return 0;
>> }
>> +
>> +static bool native_vcpu_is_preempted(int cpu)
>> +{
>> + return false;
>> +}
>> +
>> +DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
>> +
>> +static bool para_vcpu_is_preempted(int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> + __le64 preempted_le;
>> +
>> + reg = per_cpu_ptr(&lock_state_region, cpu);
>> + if (!reg->kaddr) {
>> + pr_warn_once("PV lock enabled but not configured for cpu %d\n",
>> + cpu);
>> + return false;
>> + }
>> +
>> + preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
>> +
>> + return !!(preempted_le);
>> +}
>> +
>> +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> +
>> + reg = this_cpu_ptr(&lock_state_region);
>> + if (!reg->kaddr)
>> + return 0;
>> +
>> + memunmap(reg->kaddr);
>> + memset(reg, 0, sizeof(*reg));
>> +
>> + return 0;
>> +}
>> +
>> +static int init_pvlock_vcpu_state(unsigned int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> + struct arm_smccc_res res;
>> +
>> + reg = this_cpu_ptr(&lock_state_region);
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
>> +
>> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
>> + pr_warn("Failed to init PV lock data structure\n");
>> + return -EINVAL;
>> + }
>> +
>> + reg->kaddr = memremap(res.a0,
>> + sizeof(struct pvlock_vcpu_state),
>> + MEMREMAP_WB);
>> +
>> + if (!reg->kaddr) {
>> + pr_warn("Failed to map PV lock data structure\n");
>> + return -ENOMEM;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int kvm_arm_init_pvlock(void)
>> +{
>> + int ret;
>> +
>> + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
>> + "hypervisor/arm/pvlock:starting",
>> + init_pvlock_vcpu_state,
>> + pvlock_vcpu_state_dying_cpu);
>> + if (ret < 0) {
>> + pr_warn("PV-lock init failed\n");
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static bool has_kvm_pvlock(void)
>> +{
>> + struct arm_smccc_res res;
>> +
>> + /* To detect the presence of PV lock support we require SMCCC 1.1+ */
>> + if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
>> + return false;
>
> This is unnecessary as arm_smccc_1_1_invoke() will return failure if
> there's no conduit (or pre-SMCCC 1.1). I suspect this was a copy/paste
> from has_pv_steal_clock() which also has the unnecessary check (patch
> welcome ;) ).
Thanks for the review!
I have sent a seperate patch to remove it from pv_steal_clock:
https://lore.kernel.org/all/20221104061659.4116508-1-usama.arif@bytedance.com/.
I have removed it from pv_lock as well in the v2 patchset:
https://lore.kernel.org/all/20221104062105.4119003-1-usama.arif@bytedance.com/.
>
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
>> + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
>
> Since this is a 'OWNER_VENDOR_HYP' call this should really be preceded
> by a check that we're running under the expected hypervisor. See e.g.
> kvm_init_hyp_services().
>
> Of course for KVM we already have a (different) discovery mechanism and
> this could be included as a ARM_SMCCC_KVM_FUNC_xxx feature. This
> has_kvm_pvlock() function would then simply be:
>
> static bool has_kvm_pvlock(void)
> {
> return kvm_arm_hyp_service_available(ARM_SMCC_KVM_FUNC_PVLOCK);
> }
Thanks, I have simplified has_kvm_pvlock to above. I also changed the
code in the v2 revision, so that its just 1 hypercall,
ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID. This is similar to how it is
done in ptp_kvm vendor call.
Usama
>
> Steve
>
>> +
>> + if (res.a0 != SMCCC_RET_SUCCESS)
>> + return false;
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
>> + ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
>> +
>> + return (res.a0 == SMCCC_RET_SUCCESS);
>> +}
>> +
>> +int __init pv_lock_init(void)
>> +{
>> + int ret;
>> +
>> + if (is_hyp_mode_available())
>> + return 0;
>> +
>> + if (!has_kvm_pvlock())
>> + return 0;
>> +
>> + ret = kvm_arm_init_pvlock();
>> + if (ret)
>> + return ret;
>> +
>> + static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
>> + pr_info("using PV-lock preempted\n");
>> +
>> + return 0;
>> +}
>> \ No newline at end of file
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index fea3223704b6..05ca07ac5800 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -42,6 +42,7 @@
>> #include <asm/cpu_ops.h>
>> #include <asm/kasan.h>
>> #include <asm/numa.h>
>> +#include <asm/paravirt.h>
>> #include <asm/sections.h>
>> #include <asm/setup.h>
>> #include <asm/smp_plat.h>
>> @@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
>> smp_init_cpus();
>> smp_build_mpidr_hash();
>>
>> + pv_lock_init();
>> +
>> /* Init percpu seeds for random tags after cpus are set up. */
>> kasan_init_sw_tags();
>>
>> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
>> index f61447913db9..c0ee11855c73 100644
>> --- a/include/linux/cpuhotplug.h
>> +++ b/include/linux/cpuhotplug.h
>> @@ -192,6 +192,7 @@ enum cpuhp_state {
>> /* Must be the last timer callback */
>> CPUHP_AP_DUMMY_TIMER_STARTING,
>> CPUHP_AP_ARM_XEN_STARTING,
>> + CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
>> CPUHP_AP_ARM_CORESIGHT_STARTING,
>> CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
>> CPUHP_AP_ARM64_ISNDEP_STARTING,
>
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 5/6] KVM: arm64: Support the VCPU preemption check
@ 2022-11-04 6:24 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-04 6:24 UTC (permalink / raw)
To: Steven Price, linux-kernel, linux-arm-kernel, kvmarm, kvm,
linux-doc, virtualization, linux, yezengruan, catalin.marinas,
will, maz, mark.rutland
Cc: punit.agrawal, fam.zheng, liangma
On 03/11/2022 13:25, Steven Price wrote:
> On 02/11/2022 16:13, Usama Arif wrote:
>> Support the vcpu_is_preempted() functionality under KVM/arm64. This will
>> enhance lock performance on overcommitted hosts (more runnable VCPUs
>> than physical CPUs in the system) as doing busy waits for preempted
>> VCPUs will hurt system performance far worse than early yielding.
>>
>> Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
>> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
>> ---
>> arch/arm64/include/asm/paravirt.h | 2 +
>> arch/arm64/include/asm/spinlock.h | 16 +++-
>> arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
>> arch/arm64/kernel/setup.c | 3 +
>> include/linux/cpuhotplug.h | 1 +
>> 5 files changed, 147 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
>> index 9aa193e0e8f2..4ccb4356c56b 100644
>> --- a/arch/arm64/include/asm/paravirt.h
>> +++ b/arch/arm64/include/asm/paravirt.h
>> @@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
>> }
>>
>> int __init pv_time_init(void);
>> +int __init pv_lock_init(void);
>>
>> #else
>>
>> #define pv_time_init() do {} while (0)
>> +#define pv_lock_init() do {} while (0)
>>
>> #endif // CONFIG_PARAVIRT
>>
>> diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
>> index 0525c0b089ed..7023efa4de96 100644
>> --- a/arch/arm64/include/asm/spinlock.h
>> +++ b/arch/arm64/include/asm/spinlock.h
>> @@ -10,7 +10,20 @@
>>
>> /* See include/linux/spinlock.h */
>> #define smp_mb__after_spinlock() smp_mb()
>> +#define vcpu_is_preempted vcpu_is_preempted
>> +
>> +#ifdef CONFIG_PARAVIRT
>> +#include <linux/static_call_types.h>
>> +
>> +bool dummy_vcpu_is_preempted(int cpu);
>>
>> +DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
>> +static inline bool vcpu_is_preempted(int cpu)
>> +{
>> + return static_call(pv_vcpu_is_preempted)(cpu);
>> +}
>> +
>> +#else
>> /*
>> * Changing this will break osq_lock() thanks to the call inside
>> * smp_cond_load_relaxed().
>> @@ -18,10 +31,11 @@
>> * See:
>> * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
>> */
>> -#define vcpu_is_preempted vcpu_is_preempted
>> static inline bool vcpu_is_preempted(int cpu)
>> {
>> return false;
>> }
>>
>> +#endif /* CONFIG_PARAVIRT */
>> +
>> #endif /* __ASM_SPINLOCK_H */
>> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
>> index 57c7c211f8c7..45bcca87bed7 100644
>> --- a/arch/arm64/kernel/paravirt.c
>> +++ b/arch/arm64/kernel/paravirt.c
>> @@ -22,6 +22,7 @@
>>
>> #include <asm/paravirt.h>
>> #include <asm/pvclock-abi.h>
>> +#include <asm/pvlock-abi.h>
>> #include <asm/smp_plat.h>
>>
>> struct static_key paravirt_steal_enabled;
>> @@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
>> struct pvclock_vcpu_stolen_time __rcu *kaddr;
>> };
>>
>> +struct pv_lock_state_region {
>> + struct pvlock_vcpu_state __rcu *kaddr;
>> +};
>> +
>> static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
>> +static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
>>
>> static bool steal_acc = true;
>> static int __init parse_no_stealacc(char *arg)
>> @@ -178,3 +184,123 @@ int __init pv_time_init(void)
>>
>> return 0;
>> }
>> +
>> +static bool native_vcpu_is_preempted(int cpu)
>> +{
>> + return false;
>> +}
>> +
>> +DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
>> +
>> +static bool para_vcpu_is_preempted(int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> + __le64 preempted_le;
>> +
>> + reg = per_cpu_ptr(&lock_state_region, cpu);
>> + if (!reg->kaddr) {
>> + pr_warn_once("PV lock enabled but not configured for cpu %d\n",
>> + cpu);
>> + return false;
>> + }
>> +
>> + preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
>> +
>> + return !!(preempted_le);
>> +}
>> +
>> +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> +
>> + reg = this_cpu_ptr(&lock_state_region);
>> + if (!reg->kaddr)
>> + return 0;
>> +
>> + memunmap(reg->kaddr);
>> + memset(reg, 0, sizeof(*reg));
>> +
>> + return 0;
>> +}
>> +
>> +static int init_pvlock_vcpu_state(unsigned int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> + struct arm_smccc_res res;
>> +
>> + reg = this_cpu_ptr(&lock_state_region);
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
>> +
>> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
>> + pr_warn("Failed to init PV lock data structure\n");
>> + return -EINVAL;
>> + }
>> +
>> + reg->kaddr = memremap(res.a0,
>> + sizeof(struct pvlock_vcpu_state),
>> + MEMREMAP_WB);
>> +
>> + if (!reg->kaddr) {
>> + pr_warn("Failed to map PV lock data structure\n");
>> + return -ENOMEM;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int kvm_arm_init_pvlock(void)
>> +{
>> + int ret;
>> +
>> + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
>> + "hypervisor/arm/pvlock:starting",
>> + init_pvlock_vcpu_state,
>> + pvlock_vcpu_state_dying_cpu);
>> + if (ret < 0) {
>> + pr_warn("PV-lock init failed\n");
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static bool has_kvm_pvlock(void)
>> +{
>> + struct arm_smccc_res res;
>> +
>> + /* To detect the presence of PV lock support we require SMCCC 1.1+ */
>> + if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
>> + return false;
>
> This is unnecessary as arm_smccc_1_1_invoke() will return failure if
> there's no conduit (or pre-SMCCC 1.1). I suspect this was a copy/paste
> from has_pv_steal_clock() which also has the unnecessary check (patch
> welcome ;) ).
Thanks for the review!
I have sent a seperate patch to remove it from pv_steal_clock:
https://lore.kernel.org/all/20221104061659.4116508-1-usama.arif@bytedance.com/.
I have removed it from pv_lock as well in the v2 patchset:
https://lore.kernel.org/all/20221104062105.4119003-1-usama.arif@bytedance.com/.
>
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
>> + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
>
> Since this is a 'OWNER_VENDOR_HYP' call this should really be preceded
> by a check that we're running under the expected hypervisor. See e.g.
> kvm_init_hyp_services().
>
> Of course for KVM we already have a (different) discovery mechanism and
> this could be included as a ARM_SMCCC_KVM_FUNC_xxx feature. This
> has_kvm_pvlock() function would then simply be:
>
> static bool has_kvm_pvlock(void)
> {
> return kvm_arm_hyp_service_available(ARM_SMCC_KVM_FUNC_PVLOCK);
> }
Thanks, I have simplified has_kvm_pvlock to above. I also changed the
code in the v2 revision, so that its just 1 hypercall,
ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID. This is similar to how it is
done in ptp_kvm vendor call.
Usama
>
> Steve
>
>> +
>> + if (res.a0 != SMCCC_RET_SUCCESS)
>> + return false;
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
>> + ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
>> +
>> + return (res.a0 == SMCCC_RET_SUCCESS);
>> +}
>> +
>> +int __init pv_lock_init(void)
>> +{
>> + int ret;
>> +
>> + if (is_hyp_mode_available())
>> + return 0;
>> +
>> + if (!has_kvm_pvlock())
>> + return 0;
>> +
>> + ret = kvm_arm_init_pvlock();
>> + if (ret)
>> + return ret;
>> +
>> + static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
>> + pr_info("using PV-lock preempted\n");
>> +
>> + return 0;
>> +}
>> \ No newline at end of file
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index fea3223704b6..05ca07ac5800 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -42,6 +42,7 @@
>> #include <asm/cpu_ops.h>
>> #include <asm/kasan.h>
>> #include <asm/numa.h>
>> +#include <asm/paravirt.h>
>> #include <asm/sections.h>
>> #include <asm/setup.h>
>> #include <asm/smp_plat.h>
>> @@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
>> smp_init_cpus();
>> smp_build_mpidr_hash();
>>
>> + pv_lock_init();
>> +
>> /* Init percpu seeds for random tags after cpus are set up. */
>> kasan_init_sw_tags();
>>
>> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
>> index f61447913db9..c0ee11855c73 100644
>> --- a/include/linux/cpuhotplug.h
>> +++ b/include/linux/cpuhotplug.h
>> @@ -192,6 +192,7 @@ enum cpuhp_state {
>> /* Must be the last timer callback */
>> CPUHP_AP_DUMMY_TIMER_STARTING,
>> CPUHP_AP_ARM_XEN_STARTING,
>> + CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
>> CPUHP_AP_ARM_CORESIGHT_STARTING,
>> CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
>> CPUHP_AP_ARM64_ISNDEP_STARTING,
>
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 36+ messages in thread
* Re: [External] Re: [RFC 5/6] KVM: arm64: Support the VCPU preemption check
@ 2022-11-04 6:24 ` Usama Arif
0 siblings, 0 replies; 36+ messages in thread
From: Usama Arif @ 2022-11-04 6:24 UTC (permalink / raw)
To: Steven Price, linux-kernel, linux-arm-kernel, kvmarm, kvm,
linux-doc, virtualization, linux, yezengruan, catalin.marinas,
will, maz, mark.rutland
Cc: fam.zheng, liangma, punit.agrawal
On 03/11/2022 13:25, Steven Price wrote:
> On 02/11/2022 16:13, Usama Arif wrote:
>> Support the vcpu_is_preempted() functionality under KVM/arm64. This will
>> enhance lock performance on overcommitted hosts (more runnable VCPUs
>> than physical CPUs in the system) as doing busy waits for preempted
>> VCPUs will hurt system performance far worse than early yielding.
>>
>> Signed-off-by: Zengruan Ye <yezengruan@huawei.com>
>> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
>> ---
>> arch/arm64/include/asm/paravirt.h | 2 +
>> arch/arm64/include/asm/spinlock.h | 16 +++-
>> arch/arm64/kernel/paravirt.c | 126 ++++++++++++++++++++++++++++++
>> arch/arm64/kernel/setup.c | 3 +
>> include/linux/cpuhotplug.h | 1 +
>> 5 files changed, 147 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
>> index 9aa193e0e8f2..4ccb4356c56b 100644
>> --- a/arch/arm64/include/asm/paravirt.h
>> +++ b/arch/arm64/include/asm/paravirt.h
>> @@ -19,10 +19,12 @@ static inline u64 paravirt_steal_clock(int cpu)
>> }
>>
>> int __init pv_time_init(void);
>> +int __init pv_lock_init(void);
>>
>> #else
>>
>> #define pv_time_init() do {} while (0)
>> +#define pv_lock_init() do {} while (0)
>>
>> #endif // CONFIG_PARAVIRT
>>
>> diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
>> index 0525c0b089ed..7023efa4de96 100644
>> --- a/arch/arm64/include/asm/spinlock.h
>> +++ b/arch/arm64/include/asm/spinlock.h
>> @@ -10,7 +10,20 @@
>>
>> /* See include/linux/spinlock.h */
>> #define smp_mb__after_spinlock() smp_mb()
>> +#define vcpu_is_preempted vcpu_is_preempted
>> +
>> +#ifdef CONFIG_PARAVIRT
>> +#include <linux/static_call_types.h>
>> +
>> +bool dummy_vcpu_is_preempted(int cpu);
>>
>> +DECLARE_STATIC_CALL(pv_vcpu_is_preempted, dummy_vcpu_is_preempted);
>> +static inline bool vcpu_is_preempted(int cpu)
>> +{
>> + return static_call(pv_vcpu_is_preempted)(cpu);
>> +}
>> +
>> +#else
>> /*
>> * Changing this will break osq_lock() thanks to the call inside
>> * smp_cond_load_relaxed().
>> @@ -18,10 +31,11 @@
>> * See:
>> * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
>> */
>> -#define vcpu_is_preempted vcpu_is_preempted
>> static inline bool vcpu_is_preempted(int cpu)
>> {
>> return false;
>> }
>>
>> +#endif /* CONFIG_PARAVIRT */
>> +
>> #endif /* __ASM_SPINLOCK_H */
>> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
>> index 57c7c211f8c7..45bcca87bed7 100644
>> --- a/arch/arm64/kernel/paravirt.c
>> +++ b/arch/arm64/kernel/paravirt.c
>> @@ -22,6 +22,7 @@
>>
>> #include <asm/paravirt.h>
>> #include <asm/pvclock-abi.h>
>> +#include <asm/pvlock-abi.h>
>> #include <asm/smp_plat.h>
>>
>> struct static_key paravirt_steal_enabled;
>> @@ -38,7 +39,12 @@ struct pv_time_stolen_time_region {
>> struct pvclock_vcpu_stolen_time __rcu *kaddr;
>> };
>>
>> +struct pv_lock_state_region {
>> + struct pvlock_vcpu_state __rcu *kaddr;
>> +};
>> +
>> static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
>> +static DEFINE_PER_CPU(struct pv_lock_state_region, lock_state_region);
>>
>> static bool steal_acc = true;
>> static int __init parse_no_stealacc(char *arg)
>> @@ -178,3 +184,123 @@ int __init pv_time_init(void)
>>
>> return 0;
>> }
>> +
>> +static bool native_vcpu_is_preempted(int cpu)
>> +{
>> + return false;
>> +}
>> +
>> +DEFINE_STATIC_CALL(pv_vcpu_is_preempted, native_vcpu_is_preempted);
>> +
>> +static bool para_vcpu_is_preempted(int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> + __le64 preempted_le;
>> +
>> + reg = per_cpu_ptr(&lock_state_region, cpu);
>> + if (!reg->kaddr) {
>> + pr_warn_once("PV lock enabled but not configured for cpu %d\n",
>> + cpu);
>> + return false;
>> + }
>> +
>> + preempted_le = le64_to_cpu(READ_ONCE(reg->kaddr->preempted));
>> +
>> + return !!(preempted_le);
>> +}
>> +
>> +static int pvlock_vcpu_state_dying_cpu(unsigned int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> +
>> + reg = this_cpu_ptr(&lock_state_region);
>> + if (!reg->kaddr)
>> + return 0;
>> +
>> + memunmap(reg->kaddr);
>> + memset(reg, 0, sizeof(*reg));
>> +
>> + return 0;
>> +}
>> +
>> +static int init_pvlock_vcpu_state(unsigned int cpu)
>> +{
>> + struct pv_lock_state_region *reg;
>> + struct arm_smccc_res res;
>> +
>> + reg = this_cpu_ptr(&lock_state_region);
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
>> +
>> + if (res.a0 == SMCCC_RET_NOT_SUPPORTED) {
>> + pr_warn("Failed to init PV lock data structure\n");
>> + return -EINVAL;
>> + }
>> +
>> + reg->kaddr = memremap(res.a0,
>> + sizeof(struct pvlock_vcpu_state),
>> + MEMREMAP_WB);
>> +
>> + if (!reg->kaddr) {
>> + pr_warn("Failed to map PV lock data structure\n");
>> + return -ENOMEM;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int kvm_arm_init_pvlock(void)
>> +{
>> + int ret;
>> +
>> + ret = cpuhp_setup_state(CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
>> + "hypervisor/arm/pvlock:starting",
>> + init_pvlock_vcpu_state,
>> + pvlock_vcpu_state_dying_cpu);
>> + if (ret < 0) {
>> + pr_warn("PV-lock init failed\n");
>> + return ret;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static bool has_kvm_pvlock(void)
>> +{
>> + struct arm_smccc_res res;
>> +
>> + /* To detect the presence of PV lock support we require SMCCC 1.1+ */
>> + if (arm_smccc_1_1_get_conduit() == SMCCC_CONDUIT_NONE)
>> + return false;
>
> This is unnecessary as arm_smccc_1_1_invoke() will return failure if
> there's no conduit (or pre-SMCCC 1.1). I suspect this was a copy/paste
> from has_pv_steal_clock() which also has the unnecessary check (patch
> welcome ;) ).
Thanks for the review!
I have sent a seperate patch to remove it from pv_steal_clock:
https://lore.kernel.org/all/20221104061659.4116508-1-usama.arif@bytedance.com/.
I have removed it from pv_lock as well in the v2 patchset:
https://lore.kernel.org/all/20221104062105.4119003-1-usama.arif@bytedance.com/.
>
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_ARCH_FEATURES_FUNC_ID,
>> + ARM_SMCCC_HV_PV_LOCK_FEATURES, &res);
>
> Since this is a 'OWNER_VENDOR_HYP' call this should really be preceded
> by a check that we're running under the expected hypervisor. See e.g.
> kvm_init_hyp_services().
>
> Of course for KVM we already have a (different) discovery mechanism and
> this could be included as a ARM_SMCCC_KVM_FUNC_xxx feature. This
> has_kvm_pvlock() function would then simply be:
>
> static bool has_kvm_pvlock(void)
> {
> return kvm_arm_hyp_service_available(ARM_SMCC_KVM_FUNC_PVLOCK);
> }
Thanks, I have simplified has_kvm_pvlock to above. I also changed the
code in the v2 revision, so that its just 1 hypercall,
ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID. This is similar to how it is
done in ptp_kvm vendor call.
Usama
>
> Steve
>
>> +
>> + if (res.a0 != SMCCC_RET_SUCCESS)
>> + return false;
>> +
>> + arm_smccc_1_1_invoke(ARM_SMCCC_HV_PV_LOCK_FEATURES,
>> + ARM_SMCCC_HV_PV_LOCK_PREEMPTED, &res);
>> +
>> + return (res.a0 == SMCCC_RET_SUCCESS);
>> +}
>> +
>> +int __init pv_lock_init(void)
>> +{
>> + int ret;
>> +
>> + if (is_hyp_mode_available())
>> + return 0;
>> +
>> + if (!has_kvm_pvlock())
>> + return 0;
>> +
>> + ret = kvm_arm_init_pvlock();
>> + if (ret)
>> + return ret;
>> +
>> + static_call_update(pv_vcpu_is_preempted, para_vcpu_is_preempted);
>> + pr_info("using PV-lock preempted\n");
>> +
>> + return 0;
>> +}
>> \ No newline at end of file
>> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
>> index fea3223704b6..05ca07ac5800 100644
>> --- a/arch/arm64/kernel/setup.c
>> +++ b/arch/arm64/kernel/setup.c
>> @@ -42,6 +42,7 @@
>> #include <asm/cpu_ops.h>
>> #include <asm/kasan.h>
>> #include <asm/numa.h>
>> +#include <asm/paravirt.h>
>> #include <asm/sections.h>
>> #include <asm/setup.h>
>> #include <asm/smp_plat.h>
>> @@ -360,6 +361,8 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
>> smp_init_cpus();
>> smp_build_mpidr_hash();
>>
>> + pv_lock_init();
>> +
>> /* Init percpu seeds for random tags after cpus are set up. */
>> kasan_init_sw_tags();
>>
>> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
>> index f61447913db9..c0ee11855c73 100644
>> --- a/include/linux/cpuhotplug.h
>> +++ b/include/linux/cpuhotplug.h
>> @@ -192,6 +192,7 @@ enum cpuhp_state {
>> /* Must be the last timer callback */
>> CPUHP_AP_DUMMY_TIMER_STARTING,
>> CPUHP_AP_ARM_XEN_STARTING,
>> + CPUHP_AP_ARM_KVM_PVLOCK_STARTING,
>> CPUHP_AP_ARM_CORESIGHT_STARTING,
>> CPUHP_AP_ARM_CORESIGHT_CTI_STARTING,
>> CPUHP_AP_ARM64_ISNDEP_STARTING,
>
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^ permalink raw reply [flat|nested] 36+ messages in thread
end of thread, other threads:[~2022-11-04 6:31 UTC | newest]
Thread overview: 36+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-11-02 16:13 [RFC 0/6] KVM: arm64: implement vcpu_is_preempted check Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` [RFC 1/6] KVM: arm64: Document PV-lock interface Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-03 3:50 ` Bagas Sanjaya
2022-11-03 3:50 ` Bagas Sanjaya
2022-11-03 3:50 ` Bagas Sanjaya
2022-11-03 13:15 ` [External] " Usama Arif
2022-11-03 13:15 ` Usama Arif
2022-11-03 13:15 ` Usama Arif
2022-11-03 13:56 ` Bagas Sanjaya
2022-11-03 13:56 ` Bagas Sanjaya
2022-11-03 13:56 ` Bagas Sanjaya
2022-11-02 16:13 ` [RFC 2/6] KVM: arm64: Add SMCCC paravirtualised lock calls Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` [RFC 3/6] KVM: arm64: Support pvlock preempted via shared structure Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` [RFC 4/6] KVM: arm64: Provide VCPU attributes for PV lock Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` [RFC 5/6] KVM: arm64: Support the VCPU preemption check Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-03 13:25 ` Steven Price
2022-11-03 13:25 ` Steven Price
2022-11-03 13:25 ` Steven Price
2022-11-04 6:24 ` [External] " Usama Arif
2022-11-04 6:24 ` Usama Arif
2022-11-04 6:24 ` Usama Arif
2022-11-02 16:13 ` [RFC 6/6] KVM: selftests: add tests for PV time specific hypercalls Usama Arif
2022-11-02 16:13 ` Usama Arif
2022-11-02 16:13 ` Usama Arif
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