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* [PATCH v4 00/19] KVM: Dynamically size memslot arrays
@ 2019-12-17 20:40 Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
                   ` (20 more replies)
  0 siblings, 21 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

The end goal of this series is to dynamically size the memslot array so
that KVM allocates memory based on the number of memslots in use, as
opposed to unconditionally allocating memory for the maximum number of
memslots.  On x86, each memslot consumes 88 bytes, and so with 2 address
spaces of 512 memslots, each VM consumes ~90k bytes for the memslots.
E.g. given a VM that uses a total of 30 memslots, dynamic sizing reduces
the memory footprint from 90k to ~2.6k bytes.

The changes required to support dynamic sizing are relatively small,
e.g. are essentially contained in patches 17/19 and 18/19.

Patches 2-16 clean up the memslot code, which has gotten quite crusty,
especially __kvm_set_memory_region().  The clean up is likely not strictly
necessary to switch to dynamic sizing, but I didn't have a remotely
reasonable level of confidence in the correctness of the dynamic sizing
without first doing the clean up.

The only functional change in v4 is the addition of an x86-specific bug
fix in x86's handling of KVM_MR_MOVE.  The bug fix is not directly related
to dynamically allocating memslots, but it has subtle and hidden conflicts
with the cleanup patches, and the fix is higher priority than anything
else in the series, i.e. should be merged first.

On non-x86 architectures, v3 and v4 should be functionally equivalent,
the only non-x86 change in v4 is the dropping of a "const" in
kvm_arch_commit_memory_region().

v4:
  - Add patch 01 to fix an x86 rmap/lpage bug, and patches 10 and 11 to
    resolve hidden conflicts with the bug fix.
  - Collect tags [Christian, Marc, Philippe].
  - Rebase to kvm/queue, commit e41a90be9659 ("KVM: x86/mmu: WARN if
    root_hpa is invalid when handling a page fault").
v3:
  - Fix build errors on PPC and MIPS due to missed params during
    refactoring [kbuild test robot].
  - Rename the helpers for update_memslots() and add comments describing
    the new algorithm and how it interacts with searching [Paolo].
  - Remove the unnecessary and obnoxious warning regarding memslots being
    a flexible array [Paolo].
  - Fix typos in the changelog of patch 09/15 [Christoffer].
  - Collect tags [Christoffer].

v2:
  - Split "Drop kvm_arch_create_memslot()" into three patches to move
    minor functional changes to standalone patches [Janosch].
  - Rebase to latest kvm/queue (f0574a1cea5b, "KVM: x86: fix ...")
  - Collect an Acked-by and a Reviewed-by

Sean Christopherson (19):
  KVM: x86: Allocate new rmap and large page tracking when moving
    memslot
  KVM: Reinstall old memslots if arch preparation fails
  KVM: Don't free new memslot if allocation of said memslot fails
  KVM: PPC: Move memslot memory allocation into prepare_memory_region()
  KVM: x86: Allocate memslot resources during prepare_memory_region()
  KVM: Drop kvm_arch_create_memslot()
  KVM: Explicitly free allocated-but-unused dirty bitmap
  KVM: Refactor error handling for setting memory region
  KVM: Move setting of memslot into helper routine
  KVM: Drop "const" attribute from old memslot in commit_memory_region()
  KVM: x86: Free arrays for old memslot when moving memslot's base gfn
  KVM: Move memslot deletion to helper function
  KVM: Simplify kvm_free_memslot() and all its descendents
  KVM: Clean up local variable usage in __kvm_set_memory_region()
  KVM: Provide common implementation for generic dirty log functions
  KVM: Ensure validity of memslot with respect to kvm_get_dirty_log()
  KVM: Terminate memslot walks via used_slots
  KVM: Dynamically size memslot array based on number of used slots
  KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION

 arch/mips/include/asm/kvm_host.h              |   2 +-
 arch/mips/kvm/mips.c                          |  71 +-
 arch/powerpc/include/asm/kvm_ppc.h            |  17 +-
 arch/powerpc/kvm/book3s.c                     |  22 +-
 arch/powerpc/kvm/book3s_hv.c                  |  36 +-
 arch/powerpc/kvm/book3s_pr.c                  |  20 +-
 arch/powerpc/kvm/booke.c                      |  17 +-
 arch/powerpc/kvm/powerpc.c                    |  15 +-
 arch/s390/include/asm/kvm_host.h              |   2 +-
 arch/s390/kvm/kvm-s390.c                      |  23 +-
 arch/x86/include/asm/kvm_page_track.h         |   3 +-
 arch/x86/kvm/mmu/page_track.c                 |  15 +-
 arch/x86/kvm/x86.c                            | 114 +---
 include/linux/kvm_host.h                      |  48 +-
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   3 +
 .../testing/selftests/kvm/include/kvm_util.h  |   1 +
 tools/testing/selftests/kvm/lib/kvm_util.c    |  30 +
 .../selftests/kvm/set_memory_region_test.c    | 142 ++++
 virt/kvm/arm/arm.c                            |  48 +-
 virt/kvm/arm/mmu.c                            |  20 +-
 virt/kvm/kvm_main.c                           | 621 ++++++++++++------
 22 files changed, 736 insertions(+), 535 deletions(-)
 create mode 100644 tools/testing/selftests/kvm/set_memory_region_test.c

-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:48   ` Sean Christopherson
  2019-12-17 21:56   ` Peter Xu
  2019-12-17 20:40 ` [PATCH v4 02/19] KVM: Reinstall old memslots if arch preparation fails Sean Christopherson
                   ` (19 subsequent siblings)
  20 siblings, 2 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Reallocate a rmap array and recalcuate large page compatibility when
moving an existing memslot to correctly handle the alignment properties
of the new memslot.  The number of rmap entries required at each level
is dependent on the alignment of the memslot's base gfn with respect to
that level, e.g. moving a large-page aligned memslot so that it becomes
unaligned will increase the number of rmap entries needed at the now
unaligned level.

Not updating the rmap array is the most obvious bug, as KVM accesses
garbage data beyond the end of the rmap.  KVM interprets the bad data as
pointers, leading to non-canonical #GPs, unexpected #PFs, etc...

  general protection fault: 0000 [#1] SMP
  CPU: 0 PID: 1909 Comm: move_memory_reg Not tainted 5.4.0-rc7+ #139
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
  RIP: 0010:rmap_get_first+0x37/0x50 [kvm]
  Code: <48> 8b 3b 48 85 ff 74 ec e8 6c f4 ff ff 85 c0 74 e3 48 89 d8 5b c3
  RSP: 0018:ffffc9000021bbc8 EFLAGS: 00010246
  RAX: ffff00617461642e RBX: ffff00617461642e RCX: 0000000000000012
  RDX: ffff88827400f568 RSI: ffffc9000021bbe0 RDI: ffff88827400f570
  RBP: 0010000000000000 R08: ffffc9000021bd00 R09: ffffc9000021bda8
  R10: ffffc9000021bc48 R11: 0000000000000000 R12: 0030000000000000
  R13: 0000000000000000 R14: ffff88827427d700 R15: ffffc9000021bce8
  FS:  00007f7eda014700(0000) GS:ffff888277a00000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007f7ed9216ff8 CR3: 0000000274391003 CR4: 0000000000162eb0
  Call Trace:
   kvm_mmu_slot_set_dirty+0xa1/0x150 [kvm]
   __kvm_set_memory_region.part.64+0x559/0x960 [kvm]
   kvm_set_memory_region+0x45/0x60 [kvm]
   kvm_vm_ioctl+0x30f/0x920 [kvm]
   do_vfs_ioctl+0xa1/0x620
   ksys_ioctl+0x66/0x70
   __x64_sys_ioctl+0x16/0x20
   do_syscall_64+0x4c/0x170
   entry_SYSCALL_64_after_hwframe+0x44/0xa9
  RIP: 0033:0x7f7ed9911f47
  Code: <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 21 6f 2c 00 f7 d8 64 89 01 48
  RSP: 002b:00007ffc00937498 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 0000000001ab0010 RCX: 00007f7ed9911f47
  RDX: 0000000001ab1350 RSI: 000000004020ae46 RDI: 0000000000000004
  RBP: 000000000000000a R08: 0000000000000000 R09: 00007f7ed9214700
  R10: 00007f7ed92149d0 R11: 0000000000000246 R12: 00000000bffff000
  R13: 0000000000000003 R14: 00007f7ed9215000 R15: 0000000000000000
  Modules linked in: kvm_intel kvm irqbypass
  ---[ end trace 0c5f570b3358ca89 ]---

The disallow_lpage tracking is more subtle.  Failure to update results
in KVM creating large pages when it shouldn't, either due to stale data
or again due to indexing beyond the end of the metadata arrays, which
can lead to memory corruption and/or leaking data to guest/userspace.

Note, the arrays for the old memslot are freed by the unconditional call
to kvm_free_memslot() in __kvm_set_memory_region().

Fixes: 05da45583de9b ("KVM: MMU: large page support")
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/x86.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8bb2fb1705ff..04d1bf89da0e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9703,6 +9703,13 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 {
 	int i;
 
+	/*
+	 * Clear out the previous array pointers for the KVM_MR_MOVE case.  The
+	 * old arrays will be freed by __kvm_set_memory_region() if installing
+	 * the new memslot is successful.
+	 */
+	memset(&slot->arch, 0, sizeof(slot->arch));
+
 	for (i = 0; i < KVM_NR_PAGE_SIZES; ++i) {
 		struct kvm_lpage_info *linfo;
 		unsigned long ugfn;
@@ -9777,6 +9784,10 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
 				enum kvm_mr_change change)
 {
+	if (change == KVM_MR_MOVE)
+		return kvm_arch_create_memslot(kvm, memslot,
+					       mem->memory_size >> PAGE_SHIFT);
+
 	return 0;
 }
 
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 02/19] KVM: Reinstall old memslots if arch preparation fails
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 03/19] KVM: Don't free new memslot if allocation of said memslot fails Sean Christopherson
                   ` (18 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Reinstall the old memslots if preparing the new memory region fails
after invalidating a to-be-{re}moved memslot.

Remove the superfluous 'old_memslots' variable so that it's somewhat
clear that the error handling path needs to free the unused memslots,
not simply the 'old' memslots.

Fixes: bc6678a33d9b9 ("KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update")
Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 virt/kvm/kvm_main.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3aa21bec028d..f14bde936c09 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1002,7 +1002,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	unsigned long npages;
 	struct kvm_memory_slot *slot;
 	struct kvm_memory_slot old, new;
-	struct kvm_memslots *slots = NULL, *old_memslots;
+	struct kvm_memslots *slots;
 	int as_id, id;
 	enum kvm_mr_change change;
 
@@ -1110,7 +1110,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
 		slot = id_to_memslot(slots, id);
 		slot->flags |= KVM_MEMSLOT_INVALID;
 
-		old_memslots = install_new_memslots(kvm, as_id, slots);
+		/*
+		 * We can re-use the old memslots, the only difference from the
+		 * newly installed memslots is the invalid flag, which will get
+		 * dropped by update_memslots anyway.  We'll also revert to the
+		 * old memslots if preparing the new memory region fails.
+		 */
+		slots = install_new_memslots(kvm, as_id, slots);
 
 		/* From this point no new shadow pages pointing to a deleted,
 		 * or moved, memslot will be created.
@@ -1120,13 +1126,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 		 *	- kvm_is_visible_gfn (mmu_check_roots)
 		 */
 		kvm_arch_flush_shadow_memslot(kvm, slot);
-
-		/*
-		 * We can re-use the old_memslots from above, the only difference
-		 * from the currently installed memslots is the invalid flag.  This
-		 * will get overwritten by update_memslots anyway.
-		 */
-		slots = old_memslots;
 	}
 
 	r = kvm_arch_prepare_memory_region(kvm, &new, mem, change);
@@ -1140,15 +1139,17 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	}
 
 	update_memslots(slots, &new, change);
-	old_memslots = install_new_memslots(kvm, as_id, slots);
+	slots = install_new_memslots(kvm, as_id, slots);
 
 	kvm_arch_commit_memory_region(kvm, mem, &old, &new, change);
 
 	kvm_free_memslot(kvm, &old, &new);
-	kvfree(old_memslots);
+	kvfree(slots);
 	return 0;
 
 out_slots:
+	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
+		slots = install_new_memslots(kvm, as_id, slots);
 	kvfree(slots);
 out_free:
 	kvm_free_memslot(kvm, &new, &old);
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 03/19] KVM: Don't free new memslot if allocation of said memslot fails
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 02/19] KVM: Reinstall old memslots if arch preparation fails Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 04/19] KVM: PPC: Move memslot memory allocation into prepare_memory_region() Sean Christopherson
                   ` (17 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

The two implementations of kvm_arch_create_memslot() in x86 and PPC are
both good citizens and free up all local resources if creation fails.
Return immediately (via a superfluous goto) instead of calling
kvm_free_memslot().

Note, the call to kvm_free_memslot() is effectively an expensive nop in
this case as there are no resources to be freed.

No functional change intended.

Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 virt/kvm/kvm_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f14bde936c09..7239e3b9dda0 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1092,7 +1092,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 		new.userspace_addr = mem->userspace_addr;
 
 		if (kvm_arch_create_memslot(kvm, &new, npages))
-			goto out_free;
+			goto out;
 	}
 
 	/* Allocate page dirty bitmap if needed */
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 04/19] KVM: PPC: Move memslot memory allocation into prepare_memory_region()
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (2 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 03/19] KVM: Don't free new memslot if allocation of said memslot fails Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 05/19] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
                   ` (16 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Allocate the rmap array during kvm_arch_prepare_memory_region() to pave
the way for removing kvm_arch_create_memslot() altogether.  Moving PPC's
memory allocation only changes the order of kernel memory allocations
between PPC and common KVM code.

No functional change intended.

Acked-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/powerpc/include/asm/kvm_ppc.h | 11 ++++-------
 arch/powerpc/kvm/book3s.c          | 12 ++++--------
 arch/powerpc/kvm/book3s_hv.c       | 25 ++++++++++++-------------
 arch/powerpc/kvm/book3s_pr.c       | 11 ++---------
 arch/powerpc/kvm/booke.c           |  9 ++-------
 arch/powerpc/kvm/powerpc.c         |  4 ++--
 6 files changed, 26 insertions(+), 46 deletions(-)

diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 3d2f871241a8..4df042355356 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -203,12 +203,10 @@ extern void kvmppc_core_destroy_vm(struct kvm *kvm);
 extern void kvmppc_core_free_memslot(struct kvm *kvm,
 				     struct kvm_memory_slot *free,
 				     struct kvm_memory_slot *dont);
-extern int kvmppc_core_create_memslot(struct kvm *kvm,
-				      struct kvm_memory_slot *slot,
-				      unsigned long npages);
 extern int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
-				const struct kvm_userspace_memory_region *mem);
+				const struct kvm_userspace_memory_region *mem,
+				enum kvm_mr_change change);
 extern void kvmppc_core_commit_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
 				const struct kvm_memory_slot *old,
@@ -281,7 +279,8 @@ struct kvmppc_ops {
 	void (*flush_memslot)(struct kvm *kvm, struct kvm_memory_slot *memslot);
 	int (*prepare_memory_region)(struct kvm *kvm,
 				     struct kvm_memory_slot *memslot,
-				     const struct kvm_userspace_memory_region *mem);
+				     const struct kvm_userspace_memory_region *mem,
+				     enum kvm_mr_change change);
 	void (*commit_memory_region)(struct kvm *kvm,
 				     const struct kvm_userspace_memory_region *mem,
 				     const struct kvm_memory_slot *old,
@@ -295,8 +294,6 @@ struct kvmppc_ops {
 	void (*mmu_destroy)(struct kvm_vcpu *vcpu);
 	void (*free_memslot)(struct kvm_memory_slot *free,
 			     struct kvm_memory_slot *dont);
-	int (*create_memslot)(struct kvm_memory_slot *slot,
-			      unsigned long npages);
 	int (*init_vm)(struct kvm *kvm);
 	void (*destroy_vm)(struct kvm *kvm);
 	int (*get_smmu_info)(struct kvm *kvm, struct kvm_ppc_smmu_info *info);
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 58a59ee998e2..2480150646ae 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -815,12 +815,6 @@ void kvmppc_core_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 	kvm->arch.kvm_ops->free_memslot(free, dont);
 }
 
-int kvmppc_core_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			       unsigned long npages)
-{
-	return kvm->arch.kvm_ops->create_memslot(slot, npages);
-}
-
 void kvmppc_core_flush_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
 	kvm->arch.kvm_ops->flush_memslot(kvm, memslot);
@@ -828,9 +822,11 @@ void kvmppc_core_flush_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot)
 
 int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
-				const struct kvm_userspace_memory_region *mem)
+				const struct kvm_userspace_memory_region *mem,
+				enum kvm_mr_change change)
 {
-	return kvm->arch.kvm_ops->prepare_memory_region(kvm, memslot, mem);
+	return kvm->arch.kvm_ops->prepare_memory_region(kvm, memslot, mem,
+							change);
 }
 
 void kvmppc_core_commit_memory_region(struct kvm *kvm,
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index dc53578193ee..b265d7511f3f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4466,20 +4466,20 @@ static void kvmppc_core_free_memslot_hv(struct kvm_memory_slot *free,
 	}
 }
 
-static int kvmppc_core_create_memslot_hv(struct kvm_memory_slot *slot,
-					 unsigned long npages)
-{
-	slot->arch.rmap = vzalloc(array_size(npages, sizeof(*slot->arch.rmap)));
-	if (!slot->arch.rmap)
-		return -ENOMEM;
-
-	return 0;
-}
-
 static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
-					struct kvm_memory_slot *memslot,
-					const struct kvm_userspace_memory_region *mem)
+					struct kvm_memory_slot *slot,
+					const struct kvm_userspace_memory_region *mem,
+					enum kvm_mr_change change)
 {
+	unsigned long npages = mem->memory_size >> PAGE_SHIFT;
+
+	if (change == KVM_MR_CREATE) {
+		slot->arch.rmap = vzalloc(array_size(npages,
+					  sizeof(*slot->arch.rmap)));
+		if (!slot->arch.rmap)
+			return -ENOMEM;
+	}
+
 	return 0;
 }
 
@@ -5537,7 +5537,6 @@ static struct kvmppc_ops kvm_ops_hv = {
 	.set_spte_hva = kvm_set_spte_hva_hv,
 	.mmu_destroy  = kvmppc_mmu_destroy_hv,
 	.free_memslot = kvmppc_core_free_memslot_hv,
-	.create_memslot = kvmppc_core_create_memslot_hv,
 	.init_vm =  kvmppc_core_init_vm_hv,
 	.destroy_vm = kvmppc_core_destroy_vm_hv,
 	.get_smmu_info = kvm_vm_ioctl_get_smmu_info_hv,
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index ce4fcf76e53e..fc0d9432013f 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -1940,7 +1940,8 @@ static void kvmppc_core_flush_memslot_pr(struct kvm *kvm,
 
 static int kvmppc_core_prepare_memory_region_pr(struct kvm *kvm,
 					struct kvm_memory_slot *memslot,
-					const struct kvm_userspace_memory_region *mem)
+					const struct kvm_userspace_memory_region *mem,
+					enum kvm_mr_change change)
 {
 	return 0;
 }
@@ -1960,13 +1961,6 @@ static void kvmppc_core_free_memslot_pr(struct kvm_memory_slot *free,
 	return;
 }
 
-static int kvmppc_core_create_memslot_pr(struct kvm_memory_slot *slot,
-					 unsigned long npages)
-{
-	return 0;
-}
-
-
 #ifdef CONFIG_PPC64
 static int kvm_vm_ioctl_get_smmu_info_pr(struct kvm *kvm,
 					 struct kvm_ppc_smmu_info *info)
@@ -2111,7 +2105,6 @@ static struct kvmppc_ops kvm_ops_pr = {
 	.set_spte_hva = kvm_set_spte_hva_pr,
 	.mmu_destroy  = kvmppc_mmu_destroy_pr,
 	.free_memslot = kvmppc_core_free_memslot_pr,
-	.create_memslot = kvmppc_core_create_memslot_pr,
 	.init_vm = kvmppc_core_init_vm_pr,
 	.destroy_vm = kvmppc_core_destroy_vm_pr,
 	.get_smmu_info = kvm_vm_ioctl_get_smmu_info_pr,
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index be9a45874194..cf2845e147c5 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1806,15 +1806,10 @@ void kvmppc_core_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 {
 }
 
-int kvmppc_core_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			       unsigned long npages)
-{
-	return 0;
-}
-
 int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				      struct kvm_memory_slot *memslot,
-				      const struct kvm_userspace_memory_region *mem)
+				      const struct kvm_userspace_memory_region *mem,
+				      enum kvm_mr_change change)
 {
 	return 0;
 }
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 416fb3d2a1d0..b0e6b33b476d 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -694,7 +694,7 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 			    unsigned long npages)
 {
-	return kvmppc_core_create_memslot(kvm, slot, npages);
+	return 0;
 }
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
@@ -702,7 +702,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   const struct kvm_userspace_memory_region *mem,
 				   enum kvm_mr_change change)
 {
-	return kvmppc_core_prepare_memory_region(kvm, memslot, mem);
+	return kvmppc_core_prepare_memory_region(kvm, memslot, mem, change);
 }
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 05/19] KVM: x86: Allocate memslot resources during prepare_memory_region()
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (3 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 04/19] KVM: PPC: Move memslot memory allocation into prepare_memory_region() Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 22:07   ` Peter Xu
  2019-12-17 20:40 ` [PATCH v4 06/19] KVM: Drop kvm_arch_create_memslot() Sean Christopherson
                   ` (15 subsequent siblings)
  20 siblings, 1 reply; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Allocate the various metadata structures associated with a new memslot
during kvm_arch_prepare_memory_region(), which paves the way for
removing kvm_arch_create_memslot() altogether.  Moving x86's memory
allocation only changes the order of kernel memory allocations between
x86 and common KVM code.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/x86.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 04d1bf89da0e..8c815b3587b4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9700,6 +9700,12 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 
 int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
 			    unsigned long npages)
+{
+	return 0;
+}
+
+static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
+				      unsigned long npages)
 {
 	int i;
 
@@ -9784,10 +9790,9 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
 				enum kvm_mr_change change)
 {
-	if (change == KVM_MR_MOVE)
-		return kvm_arch_create_memslot(kvm, memslot,
-					       mem->memory_size >> PAGE_SHIFT);
-
+	if (change == KVM_MR_CREATE || change == KVM_MR_MOVE)
+		return kvm_alloc_memslot_metadata(memslot,
+						  mem->memory_size >> PAGE_SHIFT);
 	return 0;
 }
 
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 06/19] KVM: Drop kvm_arch_create_memslot()
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (4 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 05/19] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
                   ` (14 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Remove kvm_arch_create_memslot() now that all arch implementations are
effectively nops.  Removing kvm_arch_create_memslot() eliminates the
possibility for arch specific code to allocate memory prior to setting
a memslot, which sets the stage for simplifying kvm_free_memslot().

Cc: Janosch Frank <frankja@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/mips/kvm/mips.c       |  6 ------
 arch/powerpc/kvm/powerpc.c |  6 ------
 arch/s390/kvm/kvm-s390.c   |  6 ------
 arch/x86/kvm/x86.c         |  6 ------
 include/linux/kvm_host.h   |  2 --
 virt/kvm/arm/mmu.c         |  6 ------
 virt/kvm/kvm_main.c        | 21 +++++++--------------
 7 files changed, 7 insertions(+), 46 deletions(-)

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 1109924560d8..713e5465edb0 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -188,12 +188,6 @@ long kvm_arch_dev_ioctl(struct file *filp, unsigned int ioctl,
 	return -ENOIOCTLCMD;
 }
 
-int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			    unsigned long npages)
-{
-	return 0;
-}
-
 void kvm_arch_flush_shadow_all(struct kvm *kvm)
 {
 	/* Flush whole GPA */
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index b0e6b33b476d..c922711a6dd8 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -691,12 +691,6 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 	kvmppc_core_free_memslot(kvm, free, dont);
 }
 
-int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			    unsigned long npages)
-{
-	return 0;
-}
-
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,
 				   const struct kvm_userspace_memory_region *mem,
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index d9e6bf3d54f0..1be45bad7849 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4491,12 +4491,6 @@ vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
 	return VM_FAULT_SIGBUS;
 }
 
-int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			    unsigned long npages)
-{
-	return 0;
-}
-
 /* Section: memory related */
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				   struct kvm_memory_slot *memslot,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 8c815b3587b4..4892ded361b3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9698,12 +9698,6 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 	kvm_page_track_free_memslot(free, dont);
 }
 
-int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			    unsigned long npages)
-{
-	return 0;
-}
-
 static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
 				      unsigned long npages)
 {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 339de08e5fa2..46dd713da634 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -674,8 +674,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 			    const struct kvm_userspace_memory_region *mem);
 void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 			   struct kvm_memory_slot *dont);
-int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			    unsigned long npages);
 void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen);
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 38b4c910b6c3..f264de85f648 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -2358,12 +2358,6 @@ void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
 {
 }
 
-int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
-			    unsigned long npages)
-{
-	return 0;
-}
-
 void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen)
 {
 }
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7239e3b9dda0..d403e93e3028 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1043,12 +1043,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	new.base_gfn = base_gfn;
 	new.npages = npages;
 	new.flags = mem->flags;
+	new.userspace_addr = mem->userspace_addr;
 
 	if (npages) {
 		if (!old.npages)
 			change = KVM_MR_CREATE;
 		else { /* Modify an existing slot. */
-			if ((mem->userspace_addr != old.userspace_addr) ||
+			if ((new.userspace_addr != old.userspace_addr) ||
 			    (npages != old.npages) ||
 			    ((new.flags ^ old.flags) & KVM_MEM_READONLY))
 				goto out;
@@ -1083,22 +1084,14 @@ int __kvm_set_memory_region(struct kvm *kvm,
 		}
 	}
 
-	/* Free page dirty bitmap if unneeded */
-	if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
-		new.dirty_bitmap = NULL;
-
 	r = -ENOMEM;
-	if (change == KVM_MR_CREATE) {
-		new.userspace_addr = mem->userspace_addr;
 
-		if (kvm_arch_create_memslot(kvm, &new, npages))
-			goto out;
-	}
-
-	/* Allocate page dirty bitmap if needed */
-	if ((new.flags & KVM_MEM_LOG_DIRTY_PAGES) && !new.dirty_bitmap) {
+	/* Allocate/free page dirty bitmap as needed */
+	if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
+		new.dirty_bitmap = NULL;
+	else if (!new.dirty_bitmap) {
 		if (kvm_create_dirty_bitmap(&new) < 0)
-			goto out_free;
+			goto out;
 	}
 
 	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (5 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 06/19] KVM: Drop kvm_arch_create_memslot() Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 22:24   ` Peter Xu
  2019-12-17 20:40 ` [PATCH v4 08/19] KVM: Refactor error handling for setting memory region Sean Christopherson
                   ` (13 subsequent siblings)
  20 siblings, 1 reply; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Explicitly free an allocated-but-unused dirty bitmap instead of relying
on kvm_free_memslot() if an error occurs in __kvm_set_memory_region().
There is no longer a need to abuse kvm_free_memslot() to free arch
specific resources as arch specific code is now called only after the
common flow is guaranteed to succeed.  Arch code can still fail, but
it's responsible for its own cleanup in that case.

Eliminating the error path's abuse of kvm_free_memslot() paves the way
for simplifying kvm_free_memslot(), i.e. dropping its @dont param.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 virt/kvm/kvm_main.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d403e93e3028..6b2261a9e139 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1096,7 +1096,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
 	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
 	if (!slots)
-		goto out_free;
+		goto out_bitmap;
 	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
 
 	if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
@@ -1144,8 +1144,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
 		slots = install_new_memslots(kvm, as_id, slots);
 	kvfree(slots);
-out_free:
-	kvm_free_memslot(kvm, &new, &old);
+out_bitmap:
+	if (new.dirty_bitmap && !old.dirty_bitmap)
+		kvm_destroy_dirty_bitmap(&new);
 out:
 	return r;
 }
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 08/19] KVM: Refactor error handling for setting memory region
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (6 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 09/19] KVM: Move setting of memslot into helper routine Sean Christopherson
                   ` (12 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Replace a big pile o' gotos with returns to make it more obvious what
error code is being returned, and to prepare for refactoring the
functional, i.e. post-checks, portion of __kvm_set_memory_region().

Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 virt/kvm/kvm_main.c | 40 ++++++++++++++++++----------------------
 1 file changed, 18 insertions(+), 22 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6b2261a9e139..9c488c653257 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1008,34 +1008,33 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
 	r = check_memory_region_flags(mem);
 	if (r)
-		goto out;
+		return r;
 
-	r = -EINVAL;
 	as_id = mem->slot >> 16;
 	id = (u16)mem->slot;
 
 	/* General sanity checks */
 	if (mem->memory_size & (PAGE_SIZE - 1))
-		goto out;
+		return -EINVAL;
 	if (mem->guest_phys_addr & (PAGE_SIZE - 1))
-		goto out;
+		return -EINVAL;
 	/* We can read the guest memory with __xxx_user() later on. */
 	if ((id < KVM_USER_MEM_SLOTS) &&
 	    ((mem->userspace_addr & (PAGE_SIZE - 1)) ||
 	     !access_ok((void __user *)(unsigned long)mem->userspace_addr,
 			mem->memory_size)))
-		goto out;
+		return -EINVAL;
 	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
-		goto out;
+		return -EINVAL;
 	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
-		goto out;
+		return -EINVAL;
 
 	slot = id_to_memslot(__kvm_memslots(kvm, as_id), id);
 	base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
 	npages = mem->memory_size >> PAGE_SHIFT;
 
 	if (npages > KVM_MEM_MAX_NR_PAGES)
-		goto out;
+		return -EINVAL;
 
 	new = old = *slot;
 
@@ -1052,20 +1051,18 @@ int __kvm_set_memory_region(struct kvm *kvm,
 			if ((new.userspace_addr != old.userspace_addr) ||
 			    (npages != old.npages) ||
 			    ((new.flags ^ old.flags) & KVM_MEM_READONLY))
-				goto out;
+				return -EINVAL;
 
 			if (base_gfn != old.base_gfn)
 				change = KVM_MR_MOVE;
 			else if (new.flags != old.flags)
 				change = KVM_MR_FLAGS_ONLY;
-			else { /* Nothing to change. */
-				r = 0;
-				goto out;
-			}
+			else /* Nothing to change. */
+				return 0;
 		}
 	} else {
 		if (!old.npages)
-			goto out;
+			return -EINVAL;
 
 		change = KVM_MR_DELETE;
 		new.base_gfn = 0;
@@ -1074,29 +1071,29 @@ int __kvm_set_memory_region(struct kvm *kvm,
 
 	if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
 		/* Check for overlaps */
-		r = -EEXIST;
 		kvm_for_each_memslot(slot, __kvm_memslots(kvm, as_id)) {
 			if (slot->id == id)
 				continue;
 			if (!((base_gfn + npages <= slot->base_gfn) ||
 			      (base_gfn >= slot->base_gfn + slot->npages)))
-				goto out;
+				return -EEXIST;
 		}
 	}
 
-	r = -ENOMEM;
-
 	/* Allocate/free page dirty bitmap as needed */
 	if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
 		new.dirty_bitmap = NULL;
 	else if (!new.dirty_bitmap) {
-		if (kvm_create_dirty_bitmap(&new) < 0)
-			goto out;
+		r = kvm_create_dirty_bitmap(&new);
+		if (r)
+			return r;
 	}
 
 	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
-	if (!slots)
+	if (!slots) {
+		r = -ENOMEM;
 		goto out_bitmap;
+	}
 	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
 
 	if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
@@ -1147,7 +1144,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 out_bitmap:
 	if (new.dirty_bitmap && !old.dirty_bitmap)
 		kvm_destroy_dirty_bitmap(&new);
-out:
 	return r;
 }
 EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 09/19] KVM: Move setting of memslot into helper routine
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (7 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 08/19] KVM: Refactor error handling for setting memory region Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 10/19] KVM: Drop "const" attribute from old memslot in commit_memory_region() Sean Christopherson
                   ` (11 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Split out the core functionality of setting a memslot into a separate
helper in preparation for moving memslot deletion into its own routine.

Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 virt/kvm/kvm_main.c | 106 ++++++++++++++++++++++++++------------------
 1 file changed, 63 insertions(+), 43 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9c488c653257..3663ac229c4d 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -986,6 +986,66 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
 	return old_memslots;
 }
 
+static int kvm_set_memslot(struct kvm *kvm,
+			   const struct kvm_userspace_memory_region *mem,
+			   const struct kvm_memory_slot *old,
+			   struct kvm_memory_slot *new, int as_id,
+			   enum kvm_mr_change change)
+{
+	struct kvm_memory_slot *slot;
+	struct kvm_memslots *slots;
+	int r;
+
+	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
+	if (!slots)
+		return -ENOMEM;
+	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
+
+	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
+		/*
+		 * Note, the INVALID flag needs to be in the appropriate entry
+		 * in the freshly allocated memslots, not in @old or @new.
+		 */
+		slot = id_to_memslot(slots, old->id);
+		slot->flags |= KVM_MEMSLOT_INVALID;
+
+		/*
+		 * We can re-use the old memslots, the only difference from the
+		 * newly installed memslots is the invalid flag, which will get
+		 * dropped by update_memslots anyway.  We'll also revert to the
+		 * old memslots if preparing the new memory region fails.
+		 */
+		slots = install_new_memslots(kvm, as_id, slots);
+
+		/* From this point no new shadow pages pointing to a deleted,
+		 * or moved, memslot will be created.
+		 *
+		 * validation of sp->gfn happens in:
+		 *	- gfn_to_hva (kvm_read_guest, gfn_to_pfn)
+		 *	- kvm_is_visible_gfn (mmu_check_roots)
+		 */
+		kvm_arch_flush_shadow_memslot(kvm, slot);
+	}
+
+	r = kvm_arch_prepare_memory_region(kvm, new, mem, change);
+	if (r)
+		goto out_slots;
+
+	update_memslots(slots, new, change);
+	slots = install_new_memslots(kvm, as_id, slots);
+
+	kvm_arch_commit_memory_region(kvm, mem, old, new, change);
+
+	kvfree(slots);
+	return 0;
+
+out_slots:
+	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
+		slots = install_new_memslots(kvm, as_id, slots);
+	kvfree(slots);
+	return r;
+}
+
 /*
  * Allocate some memory and give it an address in the guest physical address
  * space.
@@ -1002,7 +1062,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	unsigned long npages;
 	struct kvm_memory_slot *slot;
 	struct kvm_memory_slot old, new;
-	struct kvm_memslots *slots;
 	int as_id, id;
 	enum kvm_mr_change change;
 
@@ -1089,58 +1148,19 @@ int __kvm_set_memory_region(struct kvm *kvm,
 			return r;
 	}
 
-	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
-	if (!slots) {
-		r = -ENOMEM;
-		goto out_bitmap;
-	}
-	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
-
-	if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
-		slot = id_to_memslot(slots, id);
-		slot->flags |= KVM_MEMSLOT_INVALID;
-
-		/*
-		 * We can re-use the old memslots, the only difference from the
-		 * newly installed memslots is the invalid flag, which will get
-		 * dropped by update_memslots anyway.  We'll also revert to the
-		 * old memslots if preparing the new memory region fails.
-		 */
-		slots = install_new_memslots(kvm, as_id, slots);
-
-		/* From this point no new shadow pages pointing to a deleted,
-		 * or moved, memslot will be created.
-		 *
-		 * validation of sp->gfn happens in:
-		 *	- gfn_to_hva (kvm_read_guest, gfn_to_pfn)
-		 *	- kvm_is_visible_gfn (mmu_check_roots)
-		 */
-		kvm_arch_flush_shadow_memslot(kvm, slot);
-	}
-
-	r = kvm_arch_prepare_memory_region(kvm, &new, mem, change);
-	if (r)
-		goto out_slots;
-
 	/* actual memory is freed via old in kvm_free_memslot below */
 	if (change == KVM_MR_DELETE) {
 		new.dirty_bitmap = NULL;
 		memset(&new.arch, 0, sizeof(new.arch));
 	}
 
-	update_memslots(slots, &new, change);
-	slots = install_new_memslots(kvm, as_id, slots);
-
-	kvm_arch_commit_memory_region(kvm, mem, &old, &new, change);
+	r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change);
+	if (r)
+		goto out_bitmap;
 
 	kvm_free_memslot(kvm, &old, &new);
-	kvfree(slots);
 	return 0;
 
-out_slots:
-	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
-		slots = install_new_memslots(kvm, as_id, slots);
-	kvfree(slots);
 out_bitmap:
 	if (new.dirty_bitmap && !old.dirty_bitmap)
 		kvm_destroy_dirty_bitmap(&new);
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 10/19] KVM: Drop "const" attribute from old memslot in commit_memory_region()
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (8 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 09/19] KVM: Move setting of memslot into helper routine Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 11/19] KVM: x86: Free arrays for old memslot when moving memslot's base gfn Sean Christopherson
                   ` (10 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Drop the "const" attribute from @old in kvm_arch_commit_memory_region()
to allow arch specific code to free arch specific resources in the old
memslot without having to cast away the attribute.  Freeing resources in
kvm_arch_commit_memory_region() paves the way for simplifying
kvm_free_memslot() by eliminating the last usage of its @dont param.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/mips/kvm/mips.c       | 2 +-
 arch/powerpc/kvm/powerpc.c | 2 +-
 arch/s390/kvm/kvm-s390.c   | 2 +-
 arch/x86/kvm/x86.c         | 2 +-
 include/linux/kvm_host.h   | 2 +-
 virt/kvm/arm/mmu.c         | 2 +-
 virt/kvm/kvm_main.c        | 2 +-
 7 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 713e5465edb0..108ed14cbcac 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -224,7 +224,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				   const struct kvm_userspace_memory_region *mem,
-				   const struct kvm_memory_slot *old,
+				   struct kvm_memory_slot *old,
 				   const struct kvm_memory_slot *new,
 				   enum kvm_mr_change change)
 {
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index c922711a6dd8..6fd61b9dd783 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -701,7 +701,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				   const struct kvm_userspace_memory_region *mem,
-				   const struct kvm_memory_slot *old,
+				   struct kvm_memory_slot *old,
 				   const struct kvm_memory_slot *new,
 				   enum kvm_mr_change change)
 {
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 1be45bad7849..a5b917b72ca0 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -4516,7 +4516,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
-				const struct kvm_memory_slot *old,
+				struct kvm_memory_slot *old,
 				const struct kvm_memory_slot *new,
 				enum kvm_mr_change change)
 {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4892ded361b3..0911b2f634c5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9842,7 +9842,7 @@ static void kvm_mmu_slot_apply_flags(struct kvm *kvm,
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
-				const struct kvm_memory_slot *old,
+				struct kvm_memory_slot *old,
 				const struct kvm_memory_slot *new,
 				enum kvm_mr_change change)
 {
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 46dd713da634..7d86dbb467f7 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -681,7 +681,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				enum kvm_mr_change change);
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				const struct kvm_userspace_memory_region *mem,
-				const struct kvm_memory_slot *old,
+				struct kvm_memory_slot *old,
 				const struct kvm_memory_slot *new,
 				enum kvm_mr_change change);
 bool kvm_largepages_enabled(void);
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index f264de85f648..4941746929ab 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -2246,7 +2246,7 @@ int kvm_mmu_init(void)
 
 void kvm_arch_commit_memory_region(struct kvm *kvm,
 				   const struct kvm_userspace_memory_region *mem,
-				   const struct kvm_memory_slot *old,
+				   struct kvm_memory_slot *old,
 				   const struct kvm_memory_slot *new,
 				   enum kvm_mr_change change)
 {
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3663ac229c4d..acf52fa16500 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -988,7 +988,7 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
 
 static int kvm_set_memslot(struct kvm *kvm,
 			   const struct kvm_userspace_memory_region *mem,
-			   const struct kvm_memory_slot *old,
+			   struct kvm_memory_slot *old,
 			   struct kvm_memory_slot *new, int as_id,
 			   enum kvm_mr_change change)
 {
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 11/19] KVM: x86: Free arrays for old memslot when moving memslot's base gfn
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (9 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 10/19] KVM: Drop "const" attribute from old memslot in commit_memory_region() Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 22:48   ` Peter Xu
  2019-12-17 20:40 ` [PATCH v4 12/19] KVM: Move memslot deletion to helper function Sean Christopherson
                   ` (9 subsequent siblings)
  20 siblings, 1 reply; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Explicitly free the metadata arrays (stored in slot->arch) in the old
memslot structure when moving the memslot's base gfn is committed.  This
eliminates x86's dependency on kvm_free_memslot() being called when a
memlsot move is committed, and paves the way for removing the funky code
in kvm_free_memslot() that conditionally frees structures based on its
@dont param.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/x86.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0911b2f634c5..5f890812fac3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9884,6 +9884,10 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 	 */
 	if (change != KVM_MR_DELETE)
 		kvm_mmu_slot_apply_flags(kvm, (struct kvm_memory_slot *) new);
+
+	/* Free the arrays associated with the old memslot. */
+	if (change == KVM_MR_MOVE)
+		kvm_arch_free_memslot(kvm, old, NULL);
 }
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 12/19] KVM: Move memslot deletion to helper function
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (10 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 11/19] KVM: x86: Free arrays for old memslot when moving memslot's base gfn Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 13/19] KVM: Simplify kvm_free_memslot() and all its descendents Sean Christopherson
                   ` (8 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Move memslot deletion into its own routine so that the success path for
other memslot updates does not need to use kvm_free_memslot(), i.e. can
explicitly destroy the dirty bitmap when necessary.  This paves the way
for dropping @dont from kvm_free_memslot(), i.e. all callers now pass
NULL for @dont.

Add a comment above the code to make a copy of the existing memslot
prior to deletion, it is not at all obvious that the pointer will become
stale during sorting and/or installation of new memslots.

Note, kvm_arch_commit_memory_region() allows an architecture to free
resources when moving a memslot or changing its flags, e.g. x86 frees
its arch specific memslot metadata during commit_memory_region().

Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 virt/kvm/kvm_main.c | 73 +++++++++++++++++++++++++++------------------
 1 file changed, 44 insertions(+), 29 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index acf52fa16500..50e5aec0c15c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1046,6 +1046,27 @@ static int kvm_set_memslot(struct kvm *kvm,
 	return r;
 }
 
+static int kvm_delete_memslot(struct kvm *kvm,
+			      const struct kvm_userspace_memory_region *mem,
+			      struct kvm_memory_slot *old, int as_id)
+{
+	struct kvm_memory_slot new;
+	int r;
+
+	if (!old->npages)
+		return -EINVAL;
+
+	memset(&new, 0, sizeof(new));
+	new.id = old->id;
+
+	r = kvm_set_memslot(kvm, mem, old, &new, as_id, KVM_MR_DELETE);
+	if (r)
+		return r;
+
+	kvm_free_memslot(kvm, old, NULL);
+	return 0;
+}
+
 /*
  * Allocate some memory and give it an address in the guest physical address
  * space.
@@ -1095,7 +1116,15 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (npages > KVM_MEM_MAX_NR_PAGES)
 		return -EINVAL;
 
-	new = old = *slot;
+	/*
+	 * Make a full copy of the old memslot, the pointer will become stale
+	 * when the memslots are re-sorted by update_memslots().
+	 */
+	old = *slot;
+	if (!mem->memory_size)
+		return kvm_delete_memslot(kvm, mem, &old, as_id);
+
+	new = old;
 
 	new.id = id;
 	new.base_gfn = base_gfn;
@@ -1103,29 +1132,20 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	new.flags = mem->flags;
 	new.userspace_addr = mem->userspace_addr;
 
-	if (npages) {
-		if (!old.npages)
-			change = KVM_MR_CREATE;
-		else { /* Modify an existing slot. */
-			if ((new.userspace_addr != old.userspace_addr) ||
-			    (npages != old.npages) ||
-			    ((new.flags ^ old.flags) & KVM_MEM_READONLY))
-				return -EINVAL;
-
-			if (base_gfn != old.base_gfn)
-				change = KVM_MR_MOVE;
-			else if (new.flags != old.flags)
-				change = KVM_MR_FLAGS_ONLY;
-			else /* Nothing to change. */
-				return 0;
-		}
-	} else {
-		if (!old.npages)
+	if (!old.npages) {
+		change = KVM_MR_CREATE;
+	} else { /* Modify an existing slot. */
+		if ((new.userspace_addr != old.userspace_addr) ||
+		    (npages != old.npages) ||
+		    ((new.flags ^ old.flags) & KVM_MEM_READONLY))
 			return -EINVAL;
 
-		change = KVM_MR_DELETE;
-		new.base_gfn = 0;
-		new.flags = 0;
+		if (base_gfn != old.base_gfn)
+			change = KVM_MR_MOVE;
+		else if (new.flags != old.flags)
+			change = KVM_MR_FLAGS_ONLY;
+		else /* Nothing to change. */
+			return 0;
 	}
 
 	if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
@@ -1148,17 +1168,12 @@ int __kvm_set_memory_region(struct kvm *kvm,
 			return r;
 	}
 
-	/* actual memory is freed via old in kvm_free_memslot below */
-	if (change == KVM_MR_DELETE) {
-		new.dirty_bitmap = NULL;
-		memset(&new.arch, 0, sizeof(new.arch));
-	}
-
 	r = kvm_set_memslot(kvm, mem, &old, &new, as_id, change);
 	if (r)
 		goto out_bitmap;
 
-	kvm_free_memslot(kvm, &old, &new);
+	if (old.dirty_bitmap && !new.dirty_bitmap)
+		kvm_destroy_dirty_bitmap(&old);
 	return 0;
 
 out_bitmap:
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 13/19] KVM: Simplify kvm_free_memslot() and all its descendents
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (11 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 12/19] KVM: Move memslot deletion to helper function Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 14/19] KVM: Clean up local variable usage in __kvm_set_memory_region() Sean Christopherson
                   ` (7 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Now that all callers of kvm_free_memslot() pass NULL for @dont, remove
the param from the top-level routine and all arch's implementations.

No functional change intended.

Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/mips/include/asm/kvm_host.h      |  2 +-
 arch/powerpc/include/asm/kvm_ppc.h    |  6 ++----
 arch/powerpc/kvm/book3s.c             |  5 ++---
 arch/powerpc/kvm/book3s_hv.c          |  9 +++------
 arch/powerpc/kvm/book3s_pr.c          |  3 +--
 arch/powerpc/kvm/booke.c              |  3 +--
 arch/powerpc/kvm/powerpc.c            |  5 ++---
 arch/s390/include/asm/kvm_host.h      |  2 +-
 arch/x86/include/asm/kvm_page_track.h |  3 +--
 arch/x86/kvm/mmu/page_track.c         | 15 ++++++---------
 arch/x86/kvm/x86.c                    | 21 ++++++++-------------
 include/linux/kvm_host.h              |  3 +--
 virt/kvm/arm/mmu.c                    |  3 +--
 virt/kvm/kvm_main.c                   | 18 +++++++-----------
 14 files changed, 37 insertions(+), 61 deletions(-)

diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 41204a49cf95..2c343c346b79 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -1133,7 +1133,7 @@ extern unsigned long kvm_mips_get_ramsize(struct kvm *kvm);
 static inline void kvm_arch_hardware_unsetup(void) {}
 static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_free_memslot(struct kvm *kvm,
-		struct kvm_memory_slot *free, struct kvm_memory_slot *dont) {}
+					 struct kvm_memory_slot *slot) {}
 static inline void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen) {}
 static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
 static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {}
diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
index 4df042355356..033501d65340 100644
--- a/arch/powerpc/include/asm/kvm_ppc.h
+++ b/arch/powerpc/include/asm/kvm_ppc.h
@@ -201,8 +201,7 @@ extern void kvm_free_hpt_cma(struct page *page, unsigned long nr_pages);
 extern int kvmppc_core_init_vm(struct kvm *kvm);
 extern void kvmppc_core_destroy_vm(struct kvm *kvm);
 extern void kvmppc_core_free_memslot(struct kvm *kvm,
-				     struct kvm_memory_slot *free,
-				     struct kvm_memory_slot *dont);
+				     struct kvm_memory_slot *slot);
 extern int kvmppc_core_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
 				const struct kvm_userspace_memory_region *mem,
@@ -292,8 +291,7 @@ struct kvmppc_ops {
 	int (*test_age_hva)(struct kvm *kvm, unsigned long hva);
 	void (*set_spte_hva)(struct kvm *kvm, unsigned long hva, pte_t pte);
 	void (*mmu_destroy)(struct kvm_vcpu *vcpu);
-	void (*free_memslot)(struct kvm_memory_slot *free,
-			     struct kvm_memory_slot *dont);
+	void (*free_memslot)(struct kvm_memory_slot *slot);
 	int (*init_vm)(struct kvm *kvm);
 	void (*destroy_vm)(struct kvm *kvm);
 	int (*get_smmu_info)(struct kvm *kvm, struct kvm_ppc_smmu_info *info);
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 2480150646ae..b1c9b4d11b2a 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -809,10 +809,9 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 	return kvm->arch.kvm_ops->get_dirty_log(kvm, log);
 }
 
-void kvmppc_core_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
-			      struct kvm_memory_slot *dont)
+void kvmppc_core_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
-	kvm->arch.kvm_ops->free_memslot(free, dont);
+	kvm->arch.kvm_ops->free_memslot(slot);
 }
 
 void kvmppc_core_flush_memslot(struct kvm *kvm, struct kvm_memory_slot *memslot)
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index b265d7511f3f..04d5b7cf874f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4457,13 +4457,10 @@ static int kvm_vm_ioctl_get_dirty_log_hv(struct kvm *kvm,
 	return r;
 }
 
-static void kvmppc_core_free_memslot_hv(struct kvm_memory_slot *free,
-					struct kvm_memory_slot *dont)
+static void kvmppc_core_free_memslot_hv(struct kvm_memory_slot *slot)
 {
-	if (!dont || free->arch.rmap != dont->arch.rmap) {
-		vfree(free->arch.rmap);
-		free->arch.rmap = NULL;
-	}
+	vfree(slot->arch.rmap);
+	slot->arch.rmap = NULL;
 }
 
 static int kvmppc_core_prepare_memory_region_hv(struct kvm *kvm,
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index fc0d9432013f..d2ee00bc7077 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -1955,8 +1955,7 @@ static void kvmppc_core_commit_memory_region_pr(struct kvm *kvm,
 	return;
 }
 
-static void kvmppc_core_free_memslot_pr(struct kvm_memory_slot *free,
-					struct kvm_memory_slot *dont)
+static void kvmppc_core_free_memslot_pr(struct kvm_memory_slot *slot)
 {
 	return;
 }
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index cf2845e147c5..a22ff567724a 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1801,8 +1801,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 	return -ENOTSUPP;
 }
 
-void kvmppc_core_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
-			      struct kvm_memory_slot *dont)
+void kvmppc_core_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
 }
 
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 6fd61b9dd783..587d51f420e2 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -685,10 +685,9 @@ long kvm_arch_dev_ioctl(struct file *filp,
 	return -EINVAL;
 }
 
-void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
-			   struct kvm_memory_slot *dont)
+void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
-	kvmppc_core_free_memslot(kvm, free, dont);
+	kvmppc_core_free_memslot(kvm, slot);
 }
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 02f4c21c57f6..ecb50d88347d 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -917,7 +917,7 @@ static inline void kvm_arch_sync_events(struct kvm *kvm) {}
 static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {}
 static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
 static inline void kvm_arch_free_memslot(struct kvm *kvm,
-		struct kvm_memory_slot *free, struct kvm_memory_slot *dont) {}
+					 struct kvm_memory_slot *slot) {}
 static inline void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen) {}
 static inline void kvm_arch_flush_shadow_all(struct kvm *kvm) {}
 static inline void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
index 172f9749dbb2..87bd6025d91d 100644
--- a/arch/x86/include/asm/kvm_page_track.h
+++ b/arch/x86/include/asm/kvm_page_track.h
@@ -49,8 +49,7 @@ struct kvm_page_track_notifier_node {
 void kvm_page_track_init(struct kvm *kvm);
 void kvm_page_track_cleanup(struct kvm *kvm);
 
-void kvm_page_track_free_memslot(struct kvm_memory_slot *free,
-				 struct kvm_memory_slot *dont);
+void kvm_page_track_free_memslot(struct kvm_memory_slot *slot);
 int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
 				  unsigned long npages);
 
diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c
index 3521e2d176f2..d125ec379c79 100644
--- a/arch/x86/kvm/mmu/page_track.c
+++ b/arch/x86/kvm/mmu/page_track.c
@@ -19,17 +19,14 @@
 
 #include "mmu.h"
 
-void kvm_page_track_free_memslot(struct kvm_memory_slot *free,
-				 struct kvm_memory_slot *dont)
+void kvm_page_track_free_memslot(struct kvm_memory_slot *slot)
 {
 	int i;
 
-	for (i = 0; i < KVM_PAGE_TRACK_MAX; i++)
-		if (!dont || free->arch.gfn_track[i] !=
-		      dont->arch.gfn_track[i]) {
-			kvfree(free->arch.gfn_track[i]);
-			free->arch.gfn_track[i] = NULL;
-		}
+	for (i = 0; i < KVM_PAGE_TRACK_MAX; i++) {
+		kvfree(slot->arch.gfn_track[i]);
+		slot->arch.gfn_track[i] = NULL;
+	}
 }
 
 int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
@@ -48,7 +45,7 @@ int kvm_page_track_create_memslot(struct kvm_memory_slot *slot,
 	return 0;
 
 track_free:
-	kvm_page_track_free_memslot(slot, NULL);
+	kvm_page_track_free_memslot(slot);
 	return -ENOMEM;
 }
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5f890812fac3..50bef3195533 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9675,27 +9675,22 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 	kvm_hv_destroy_vm(kvm);
 }
 
-void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
-			   struct kvm_memory_slot *dont)
+void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
 	int i;
 
 	for (i = 0; i < KVM_NR_PAGE_SIZES; ++i) {
-		if (!dont || free->arch.rmap[i] != dont->arch.rmap[i]) {
-			kvfree(free->arch.rmap[i]);
-			free->arch.rmap[i] = NULL;
-		}
+		kvfree(slot->arch.rmap[i]);
+		slot->arch.rmap[i] = NULL;
+
 		if (i == 0)
 			continue;
 
-		if (!dont || free->arch.lpage_info[i - 1] !=
-			     dont->arch.lpage_info[i - 1]) {
-			kvfree(free->arch.lpage_info[i - 1]);
-			free->arch.lpage_info[i - 1] = NULL;
-		}
+		kvfree(slot->arch.lpage_info[i - 1]);
+		slot->arch.lpage_info[i - 1] = NULL;
 	}
 
-	kvm_page_track_free_memslot(free, dont);
+	kvm_page_track_free_memslot(slot);
 }
 
 static int kvm_alloc_memslot_metadata(struct kvm_memory_slot *slot,
@@ -9887,7 +9882,7 @@ void kvm_arch_commit_memory_region(struct kvm *kvm,
 
 	/* Free the arrays associated with the old memslot. */
 	if (change == KVM_MR_MOVE)
-		kvm_arch_free_memslot(kvm, old, NULL);
+		kvm_arch_free_memslot(kvm, old);
 }
 
 void kvm_arch_flush_shadow_all(struct kvm *kvm)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 7d86dbb467f7..8343ac5ee7a8 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -672,8 +672,7 @@ int kvm_set_memory_region(struct kvm *kvm,
 			  const struct kvm_userspace_memory_region *mem);
 int __kvm_set_memory_region(struct kvm *kvm,
 			    const struct kvm_userspace_memory_region *mem);
-void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
-			   struct kvm_memory_slot *dont);
+void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot);
 void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen);
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
 				struct kvm_memory_slot *memslot,
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index 4941746929ab..c49a3d5baad2 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -2353,8 +2353,7 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
 	return ret;
 }
 
-void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
-			   struct kvm_memory_slot *dont)
+void kvm_arch_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
 }
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 50e5aec0c15c..2fa40c3e7961 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -583,18 +583,14 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
 	memslot->dirty_bitmap = NULL;
 }
 
-/*
- * Free any memory in @free but not in @dont.
- */
-static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
-			      struct kvm_memory_slot *dont)
+static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
 {
-	if (!dont || free->dirty_bitmap != dont->dirty_bitmap)
-		kvm_destroy_dirty_bitmap(free);
+	kvm_destroy_dirty_bitmap(slot);
 
-	kvm_arch_free_memslot(kvm, free, dont);
+	kvm_arch_free_memslot(kvm, slot);
 
-	free->npages = 0;
+	slot->flags = 0;
+	slot->npages = 0;
 }
 
 static void kvm_free_memslots(struct kvm *kvm, struct kvm_memslots *slots)
@@ -605,7 +601,7 @@ static void kvm_free_memslots(struct kvm *kvm, struct kvm_memslots *slots)
 		return;
 
 	kvm_for_each_memslot(memslot, slots)
-		kvm_free_memslot(kvm, memslot, NULL);
+		kvm_free_memslot(kvm, memslot);
 
 	kvfree(slots);
 }
@@ -1063,7 +1059,7 @@ static int kvm_delete_memslot(struct kvm *kvm,
 	if (r)
 		return r;
 
-	kvm_free_memslot(kvm, old, NULL);
+	kvm_free_memslot(kvm, old);
 	return 0;
 }
 
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 14/19] KVM: Clean up local variable usage in __kvm_set_memory_region()
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (12 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 13/19] KVM: Simplify kvm_free_memslot() and all its descendents Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 15/19] KVM: Provide common implementation for generic dirty log functions Sean Christopherson
                   ` (6 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Clean up __kvm_set_memory_region() to achieve several goals:

  - Remove local variables that serve no real purpose
  - Improve the readability of the code
  - Better show the relationship between the 'old' and 'new' memslot
  - Prepare for dynamically sizing memslots.

Note, using 'tmp' to hold the initial memslot is not strictly necessary
at this juncture, e.g. 'old' could be directly copied from
id_to_memslot(), but keep the pointer usage as id_to_memslot() will be
able to return a NULL pointer once memslots are dynamically sized.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 virt/kvm/kvm_main.c | 47 +++++++++++++++++++++++----------------------
 1 file changed, 24 insertions(+), 23 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 2fa40c3e7961..b3e732078ab2 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1074,13 +1074,11 @@ static int kvm_delete_memslot(struct kvm *kvm,
 int __kvm_set_memory_region(struct kvm *kvm,
 			    const struct kvm_userspace_memory_region *mem)
 {
-	int r;
-	gfn_t base_gfn;
-	unsigned long npages;
-	struct kvm_memory_slot *slot;
 	struct kvm_memory_slot old, new;
-	int as_id, id;
+	struct kvm_memory_slot *tmp;
 	enum kvm_mr_change change;
+	int as_id, id;
+	int r;
 
 	r = check_memory_region_flags(mem);
 	if (r)
@@ -1105,52 +1103,55 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
 		return -EINVAL;
 
-	slot = id_to_memslot(__kvm_memslots(kvm, as_id), id);
-	base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
-	npages = mem->memory_size >> PAGE_SHIFT;
-
-	if (npages > KVM_MEM_MAX_NR_PAGES)
-		return -EINVAL;
-
 	/*
 	 * Make a full copy of the old memslot, the pointer will become stale
 	 * when the memslots are re-sorted by update_memslots().
 	 */
-	old = *slot;
+	tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id);
+	old = *tmp;
+	tmp = NULL;
+
 	if (!mem->memory_size)
 		return kvm_delete_memslot(kvm, mem, &old, as_id);
 
-	new = old;
-
 	new.id = id;
-	new.base_gfn = base_gfn;
-	new.npages = npages;
+	new.base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
+	new.npages = mem->memory_size >> PAGE_SHIFT;
 	new.flags = mem->flags;
 	new.userspace_addr = mem->userspace_addr;
 
+	if (new.npages > KVM_MEM_MAX_NR_PAGES)
+		return -EINVAL;
+
 	if (!old.npages) {
 		change = KVM_MR_CREATE;
+		new.dirty_bitmap = NULL;
+		memset(&new.arch, 0, sizeof(new.arch));
 	} else { /* Modify an existing slot. */
 		if ((new.userspace_addr != old.userspace_addr) ||
-		    (npages != old.npages) ||
+		    (new.npages != old.npages) ||
 		    ((new.flags ^ old.flags) & KVM_MEM_READONLY))
 			return -EINVAL;
 
-		if (base_gfn != old.base_gfn)
+		if (new.base_gfn != old.base_gfn)
 			change = KVM_MR_MOVE;
 		else if (new.flags != old.flags)
 			change = KVM_MR_FLAGS_ONLY;
 		else /* Nothing to change. */
 			return 0;
+
+		/* Copy dirty_bitmap and arch from the current memslot. */
+		new.dirty_bitmap = old.dirty_bitmap;
+		memcpy(&new.arch, &old.arch, sizeof(new.arch));
 	}
 
 	if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
 		/* Check for overlaps */
-		kvm_for_each_memslot(slot, __kvm_memslots(kvm, as_id)) {
-			if (slot->id == id)
+		kvm_for_each_memslot(tmp, __kvm_memslots(kvm, as_id)) {
+			if (tmp->id == id)
 				continue;
-			if (!((base_gfn + npages <= slot->base_gfn) ||
-			      (base_gfn >= slot->base_gfn + slot->npages)))
+			if (!((new.base_gfn + new.npages <= tmp->base_gfn) ||
+			      (new.base_gfn >= tmp->base_gfn + tmp->npages)))
 				return -EEXIST;
 		}
 	}
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 15/19] KVM: Provide common implementation for generic dirty log functions
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (13 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 14/19] KVM: Clean up local variable usage in __kvm_set_memory_region() Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log() Sean Christopherson
                   ` (5 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Move the implementations of KVM_GET_DIRTY_LOG and KVM_CLEAR_DIRTY_LOG
for CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT into common KVM code.
The arch specific implemenations are extremely similar, differing
only in whether the dirty log needs to be sync'd from hardware (x86)
and how the TLBs are flushed.  Add new arch hooks to handle sync
and TLB flush; the sync will also be used for non-generic dirty log
support in a future patch (s390).

The ulterior motive for providing a common implementation is to
eliminate the dependency between arch and common code with respect to
the memslot referenced by the dirty log, i.e. to make it obvious in the
code that the validity of the memslot is guaranteed, as a future patch
will rework memslot handling such that id_to_memslot() can return NULL.

Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/mips/kvm/mips.c      | 63 +++--------------------------
 arch/powerpc/kvm/book3s.c |  5 +++
 arch/powerpc/kvm/booke.c  |  5 +++
 arch/s390/kvm/kvm-s390.c  |  5 +--
 arch/x86/kvm/x86.c        | 61 ++--------------------------
 include/linux/kvm_host.h  | 21 +++++-----
 virt/kvm/arm/arm.c        | 48 ++--------------------
 virt/kvm/kvm_main.c       | 84 ++++++++++++++++++++++++++++++++-------
 8 files changed, 103 insertions(+), 189 deletions(-)

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 108ed14cbcac..879b1e29f106 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -965,69 +965,16 @@ long kvm_arch_vcpu_ioctl(struct file *filp, unsigned int ioctl,
 	return r;
 }
 
-/**
- * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot
- * @kvm: kvm instance
- * @log: slot id and address to which we copy the log
- *
- * Steps 1-4 below provide general overview of dirty page logging. See
- * kvm_get_dirty_log_protect() function description for additional details.
- *
- * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
- * always flush the TLB (step 4) even if previous step failed  and the dirty
- * bitmap may be corrupt. Regardless of previous outcome the KVM logging API
- * does not preclude user space subsequent dirty log read. Flushing TLB ensures
- * writes will be marked dirty for next log read.
- *
- *   1. Take a snapshot of the bit and clear it if needed.
- *   2. Write protect the corresponding page.
- *   3. Copy the snapshot to the userspace.
- *   4. Flush TLB's if needed.
- */
-int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
-	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
-	bool flush = false;
-	int r;
 
-	mutex_lock(&kvm->slots_lock);
-
-	r = kvm_get_dirty_log_protect(kvm, log, &flush);
-
-	if (flush) {
-		slots = kvm_memslots(kvm);
-		memslot = id_to_memslot(slots, log->slot);
-
-		/* Let implementation handle TLB/GVA invalidation */
-		kvm_mips_callbacks->flush_shadow_memslot(kvm, memslot);
-	}
-
-	mutex_unlock(&kvm->slots_lock);
-	return r;
 }
 
-int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, struct kvm_clear_dirty_log *log)
+void kvm_arch_dirty_log_tlb_flush(struct kvm *kvm,
+				  struct kvm_memory_slot *memslot)
 {
-	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
-	bool flush = false;
-	int r;
-
-	mutex_lock(&kvm->slots_lock);
-
-	r = kvm_clear_dirty_log_protect(kvm, log, &flush);
-
-	if (flush) {
-		slots = kvm_memslots(kvm);
-		memslot = id_to_memslot(slots, log->slot);
-
-		/* Let implementation handle TLB/GVA invalidation */
-		kvm_mips_callbacks->flush_shadow_memslot(kvm, memslot);
-	}
-
-	mutex_unlock(&kvm->slots_lock);
-	return r;
+	/* Let implementation handle TLB/GVA invalidation */
+	kvm_mips_callbacks->flush_shadow_memslot(kvm, memslot);
 }
 
 long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index b1c9b4d11b2a..b117ca317c0d 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -804,6 +804,11 @@ int kvmppc_core_check_requests(struct kvm_vcpu *vcpu)
 	return vcpu->kvm->arch.kvm_ops->check_requests(vcpu);
 }
 
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
+
+}
+
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 {
 	return kvm->arch.kvm_ops->get_dirty_log(kvm, log);
diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index a22ff567724a..35a4ef89a1db 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -1796,6 +1796,11 @@ int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
 	return r;
 }
 
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
+{
+
+}
+
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
 {
 	return -ENOTSUPP;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index a5b917b72ca0..9e38973fd2cc 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -569,8 +569,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	return r;
 }
 
-static void kvm_s390_sync_dirty_log(struct kvm *kvm,
-				    struct kvm_memory_slot *memslot)
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
 	int i;
 	gfn_t cur_gfn, last_gfn;
@@ -630,7 +629,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 	if (!memslot->dirty_bitmap)
 		goto out;
 
-	kvm_s390_sync_dirty_log(kvm, memslot);
+	kvm_arch_sync_dirty_log(kvm, memslot);
 	r = kvm_get_dirty_log(kvm, log, &is_dirty);
 	if (r)
 		goto out;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 50bef3195533..87fca25d5217 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4673,77 +4673,24 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
 	return 0;
 }
 
-/**
- * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot
- * @kvm: kvm instance
- * @log: slot id and address to which we copy the log
- *
- * Steps 1-4 below provide general overview of dirty page logging. See
- * kvm_get_dirty_log_protect() function description for additional details.
- *
- * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
- * always flush the TLB (step 4) even if previous step failed  and the dirty
- * bitmap may be corrupt. Regardless of previous outcome the KVM logging API
- * does not preclude user space subsequent dirty log read. Flushing TLB ensures
- * writes will be marked dirty for next log read.
- *
- *   1. Take a snapshot of the bit and clear it if needed.
- *   2. Write protect the corresponding page.
- *   3. Copy the snapshot to the userspace.
- *   4. Flush TLB's if needed.
- */
-int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
-	bool flush = false;
-	int r;
-
-	mutex_lock(&kvm->slots_lock);
-
 	/*
 	 * Flush potentially hardware-cached dirty pages to dirty_bitmap.
 	 */
 	if (kvm_x86_ops->flush_log_dirty)
 		kvm_x86_ops->flush_log_dirty(kvm);
-
-	r = kvm_get_dirty_log_protect(kvm, log, &flush);
-
-	/*
-	 * All the TLBs can be flushed out of mmu lock, see the comments in
-	 * kvm_mmu_slot_remove_write_access().
-	 */
-	lockdep_assert_held(&kvm->slots_lock);
-	if (flush)
-		kvm_flush_remote_tlbs(kvm);
-
-	mutex_unlock(&kvm->slots_lock);
-	return r;
 }
 
-int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, struct kvm_clear_dirty_log *log)
+void kvm_arch_dirty_log_tlb_flush(struct kvm *kvm,
+				  struct kvm_memory_slot *memslot)
 {
-	bool flush = false;
-	int r;
-
-	mutex_lock(&kvm->slots_lock);
-
-	/*
-	 * Flush potentially hardware-cached dirty pages to dirty_bitmap.
-	 */
-	if (kvm_x86_ops->flush_log_dirty)
-		kvm_x86_ops->flush_log_dirty(kvm);
-
-	r = kvm_clear_dirty_log_protect(kvm, log, &flush);
-
 	/*
 	 * All the TLBs can be flushed out of mmu lock, see the comments in
 	 * kvm_mmu_slot_remove_write_access().
 	 */
 	lockdep_assert_held(&kvm->slots_lock);
-	if (flush)
-		kvm_flush_remote_tlbs(kvm);
-
-	mutex_unlock(&kvm->slots_lock);
-	return r;
+	kvm_flush_remote_tlbs(kvm);
 }
 
 int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event,
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 8343ac5ee7a8..eb54d196c0cb 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -816,23 +816,20 @@ vm_fault_t kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf);
 
 int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext);
 
-int kvm_get_dirty_log(struct kvm *kvm,
-			struct kvm_dirty_log *log, int *is_dirty);
-
-int kvm_get_dirty_log_protect(struct kvm *kvm,
-			      struct kvm_dirty_log *log, bool *flush);
-int kvm_clear_dirty_log_protect(struct kvm *kvm,
-				struct kvm_clear_dirty_log *log, bool *flush);
-
 void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
 					struct kvm_memory_slot *slot,
 					gfn_t gfn_offset,
 					unsigned long mask);
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot);
 
-int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
-				struct kvm_dirty_log *log);
-int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm,
-				  struct kvm_clear_dirty_log *log);
+#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+void kvm_arch_dirty_log_tlb_flush(struct kvm *kvm,
+				  struct kvm_memory_slot *memslot);
+#else /* !CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
+int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log);
+int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
+		      int *is_dirty);
+#endif
 
 int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
 			bool line_status);
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 12e0280291ce..19f78a6c18bc 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -1240,55 +1240,15 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 	return r;
 }
 
-/**
- * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot
- * @kvm: kvm instance
- * @log: slot id and address to which we copy the log
- *
- * Steps 1-4 below provide general overview of dirty page logging. See
- * kvm_get_dirty_log_protect() function description for additional details.
- *
- * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
- * always flush the TLB (step 4) even if previous step failed  and the dirty
- * bitmap may be corrupt. Regardless of previous outcome the KVM logging API
- * does not preclude user space subsequent dirty log read. Flushing TLB ensures
- * writes will be marked dirty for next log read.
- *
- *   1. Take a snapshot of the bit and clear it if needed.
- *   2. Write protect the corresponding page.
- *   3. Copy the snapshot to the userspace.
- *   4. Flush TLB's if needed.
- */
-int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
+void kvm_arch_sync_dirty_log(struct kvm *kvm, struct kvm_memory_slot *memslot)
 {
-	bool flush = false;
-	int r;
 
-	mutex_lock(&kvm->slots_lock);
-
-	r = kvm_get_dirty_log_protect(kvm, log, &flush);
-
-	if (flush)
-		kvm_flush_remote_tlbs(kvm);
-
-	mutex_unlock(&kvm->slots_lock);
-	return r;
 }
 
-int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, struct kvm_clear_dirty_log *log)
+void kvm_arch_dirty_log_tlb_flush(struct kvm *kvm,
+				  struct kvm_memory_slot *memslot)
 {
-	bool flush = false;
-	int r;
-
-	mutex_lock(&kvm->slots_lock);
-
-	r = kvm_clear_dirty_log_protect(kvm, log, &flush);
-
-	if (flush)
-		kvm_flush_remote_tlbs(kvm);
-
-	mutex_unlock(&kvm->slots_lock);
-	return r;
+	kvm_flush_remote_tlbs(kvm);
 }
 
 static int kvm_vm_ioctl_set_device_addr(struct kvm *kvm,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b3e732078ab2..4a4b5339f229 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -859,7 +859,7 @@ static int kvm_vm_release(struct inode *inode, struct file *filp)
 
 /*
  * Allocation size is twice as large as the actual dirty bitmap size.
- * See x86's kvm_vm_ioctl_get_dirty_log() why this is needed.
+ * See kvm_vm_ioctl_get_dirty_log() why this is needed.
  */
 static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
 {
@@ -1201,6 +1201,7 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 	return kvm_set_memory_region(kvm, mem);
 }
 
+#ifndef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
 int kvm_get_dirty_log(struct kvm *kvm,
 			struct kvm_dirty_log *log, int *is_dirty)
 {
@@ -1234,13 +1235,12 @@ int kvm_get_dirty_log(struct kvm *kvm,
 }
 EXPORT_SYMBOL_GPL(kvm_get_dirty_log);
 
-#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
+#else /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
 /**
  * kvm_get_dirty_log_protect - get a snapshot of dirty pages
  *	and reenable dirty page tracking for the corresponding pages.
  * @kvm:	pointer to kvm instance
  * @log:	slot id and address to which we copy the log
- * @flush:	true if TLB flush is needed by caller
  *
  * We need to keep it in mind that VCPU threads can write to the bitmap
  * concurrently. So, to avoid losing track of dirty pages we keep the
@@ -1257,8 +1257,7 @@ EXPORT_SYMBOL_GPL(kvm_get_dirty_log);
  * exiting to userspace will be logged for the next call.
  *
  */
-int kvm_get_dirty_log_protect(struct kvm *kvm,
-			struct kvm_dirty_log *log, bool *flush)
+static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
 {
 	struct kvm_memslots *slots;
 	struct kvm_memory_slot *memslot;
@@ -1266,6 +1265,7 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
 	unsigned long n;
 	unsigned long *dirty_bitmap;
 	unsigned long *dirty_bitmap_buffer;
+	bool flush;
 
 	as_id = log->slot >> 16;
 	id = (u16)log->slot;
@@ -1279,8 +1279,10 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
 	if (!dirty_bitmap)
 		return -ENOENT;
 
+	kvm_arch_sync_dirty_log(kvm, memslot);
+
 	n = kvm_dirty_bitmap_bytes(memslot);
-	*flush = false;
+	flush = false;
 	if (kvm->manual_dirty_log_protect) {
 		/*
 		 * Unlike kvm_get_dirty_log, we always return false in *flush,
@@ -1303,7 +1305,7 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
 			if (!dirty_bitmap[i])
 				continue;
 
-			*flush = true;
+			flush = true;
 			mask = xchg(&dirty_bitmap[i], 0);
 			dirty_bitmap_buffer[i] = mask;
 
@@ -1314,21 +1316,55 @@ int kvm_get_dirty_log_protect(struct kvm *kvm,
 		spin_unlock(&kvm->mmu_lock);
 	}
 
+	if (flush)
+		kvm_arch_dirty_log_tlb_flush(kvm, memslot);
+
 	if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n))
 		return -EFAULT;
 	return 0;
 }
-EXPORT_SYMBOL_GPL(kvm_get_dirty_log_protect);
+
+
+/**
+ * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot
+ * @kvm: kvm instance
+ * @log: slot id and address to which we copy the log
+ *
+ * Steps 1-4 below provide general overview of dirty page logging. See
+ * kvm_get_dirty_log_protect() function description for additional details.
+ *
+ * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
+ * always flush the TLB (step 4) even if previous step failed  and the dirty
+ * bitmap may be corrupt. Regardless of previous outcome the KVM logging API
+ * does not preclude user space subsequent dirty log read. Flushing TLB ensures
+ * writes will be marked dirty for next log read.
+ *
+ *   1. Take a snapshot of the bit and clear it if needed.
+ *   2. Write protect the corresponding page.
+ *   3. Copy the snapshot to the userspace.
+ *   4. Flush TLB's if needed.
+ */
+static int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
+				      struct kvm_dirty_log *log)
+{
+	int r;
+
+	mutex_lock(&kvm->slots_lock);
+
+	r = kvm_get_dirty_log_protect(kvm, log);
+
+	mutex_unlock(&kvm->slots_lock);
+	return r;
+}
 
 /**
  * kvm_clear_dirty_log_protect - clear dirty bits in the bitmap
  *	and reenable dirty page tracking for the corresponding pages.
  * @kvm:	pointer to kvm instance
  * @log:	slot id and address from which to fetch the bitmap of dirty pages
- * @flush:	true if TLB flush is needed by caller
  */
-int kvm_clear_dirty_log_protect(struct kvm *kvm,
-				struct kvm_clear_dirty_log *log, bool *flush)
+static int kvm_clear_dirty_log_protect(struct kvm *kvm,
+				       struct kvm_clear_dirty_log *log)
 {
 	struct kvm_memslots *slots;
 	struct kvm_memory_slot *memslot;
@@ -1337,6 +1373,7 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
 	unsigned long i, n;
 	unsigned long *dirty_bitmap;
 	unsigned long *dirty_bitmap_buffer;
+	bool flush;
 
 	as_id = log->slot >> 16;
 	id = (u16)log->slot;
@@ -1360,7 +1397,9 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
 	    (log->num_pages < memslot->npages - log->first_page && (log->num_pages & 63)))
 	    return -EINVAL;
 
-	*flush = false;
+	kvm_arch_sync_dirty_log(kvm, memslot);
+
+	flush = false;
 	dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot);
 	if (copy_from_user(dirty_bitmap_buffer, log->dirty_bitmap, n))
 		return -EFAULT;
@@ -1383,17 +1422,32 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm,
 		 * a problem if userspace sets them in log->dirty_bitmap.
 		*/
 		if (mask) {
-			*flush = true;
+			flush = true;
 			kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot,
 								offset, mask);
 		}
 	}
 	spin_unlock(&kvm->mmu_lock);
 
+	if (flush)
+		kvm_arch_dirty_log_tlb_flush(kvm, memslot);
+
 	return 0;
 }
-EXPORT_SYMBOL_GPL(kvm_clear_dirty_log_protect);
-#endif
+
+static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm,
+					struct kvm_clear_dirty_log *log)
+{
+	int r;
+
+	mutex_lock(&kvm->slots_lock);
+
+	r = kvm_clear_dirty_log_protect(kvm, log);
+
+	mutex_unlock(&kvm->slots_lock);
+	return r;
+}
+#endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
 
 bool kvm_largepages_enabled(void)
 {
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log()
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (14 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 15/19] KVM: Provide common implementation for generic dirty log functions Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-24 18:19   ` Peter Xu
  2019-12-17 20:40 ` [PATCH v4 17/19] KVM: Terminate memslot walks via used_slots Sean Christopherson
                   ` (4 subsequent siblings)
  20 siblings, 1 reply; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Rework kvm_get_dirty_log() so that it "returns" the associated memslot
on success.  A future patch will rework memslot handling such that
id_to_memslot() can return NULL, returning the memslot makes it more
obvious that the validity of the memslot has been verified, i.e.
precludes the need to add validity checks in the arch code that are
technically unnecessary.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/powerpc/kvm/book3s_pr.c |  6 +-----
 arch/s390/kvm/kvm-s390.c     | 12 ++----------
 include/linux/kvm_host.h     |  2 +-
 virt/kvm/kvm_main.c          | 27 +++++++++++++++++++--------
 4 files changed, 23 insertions(+), 24 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index d2ee00bc7077..485ca134a949 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -1897,7 +1897,6 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
 static int kvm_vm_ioctl_get_dirty_log_pr(struct kvm *kvm,
 					 struct kvm_dirty_log *log)
 {
-	struct kvm_memslots *slots;
 	struct kvm_memory_slot *memslot;
 	struct kvm_vcpu *vcpu;
 	ulong ga, ga_end;
@@ -1907,15 +1906,12 @@ static int kvm_vm_ioctl_get_dirty_log_pr(struct kvm *kvm,
 
 	mutex_lock(&kvm->slots_lock);
 
-	r = kvm_get_dirty_log(kvm, log, &is_dirty);
+	r = kvm_get_dirty_log(kvm, log, &is_dirty, &memslot);
 	if (r)
 		goto out;
 
 	/* If nothing is dirty, don't bother messing with page tables. */
 	if (is_dirty) {
-		slots = kvm_memslots(kvm);
-		memslot = id_to_memslot(slots, log->slot);
-
 		ga = memslot->base_gfn << PAGE_SHIFT;
 		ga_end = ga + (memslot->npages << PAGE_SHIFT);
 
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 9e38973fd2cc..b0f5a3b7cb01 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -610,9 +610,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 {
 	int r;
 	unsigned long n;
-	struct kvm_memslots *slots;
 	struct kvm_memory_slot *memslot;
-	int is_dirty = 0;
+	int is_dirty;
 
 	if (kvm_is_ucontrol(kvm))
 		return -EINVAL;
@@ -623,14 +622,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 	if (log->slot >= KVM_USER_MEM_SLOTS)
 		goto out;
 
-	slots = kvm_memslots(kvm);
-	memslot = id_to_memslot(slots, log->slot);
-	r = -ENOENT;
-	if (!memslot->dirty_bitmap)
-		goto out;
-
-	kvm_arch_sync_dirty_log(kvm, memslot);
-	r = kvm_get_dirty_log(kvm, log, &is_dirty);
+	r = kvm_get_dirty_log(kvm, log, &is_dirty, &memslot);
 	if (r)
 		goto out;
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index eb54d196c0cb..7d666eedd203 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -828,7 +828,7 @@ void kvm_arch_dirty_log_tlb_flush(struct kvm *kvm,
 #else /* !CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log);
 int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
-		      int *is_dirty);
+		      int *is_dirty, struct kvm_memory_slot **memslot);
 #endif
 
 int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 4a4b5339f229..999a2a0c83f5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1202,31 +1202,42 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 }
 
 #ifndef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT
-int kvm_get_dirty_log(struct kvm *kvm,
-			struct kvm_dirty_log *log, int *is_dirty)
+/**
+ * kvm_get_dirty_log - get a snapshot of dirty pages
+ * @kvm:	pointer to kvm instance
+ * @log:	slot id and address to which we copy the log
+ * @is_dirty:	set to '1' if any dirty pages were found
+ * @memslot:	set to the associated memslot, always valid on success
+ */
+int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
+		      int *is_dirty, struct kvm_memory_slot **memslot)
 {
 	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
 	int i, as_id, id;
 	unsigned long n;
 	unsigned long any = 0;
 
+	*memslot = NULL;
+	*is_dirty = 0;
+
 	as_id = log->slot >> 16;
 	id = (u16)log->slot;
 	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
 		return -EINVAL;
 
 	slots = __kvm_memslots(kvm, as_id);
-	memslot = id_to_memslot(slots, id);
-	if (!memslot->dirty_bitmap)
+	*memslot = id_to_memslot(slots, id);
+	if (!(*memslot)->dirty_bitmap)
 		return -ENOENT;
 
-	n = kvm_dirty_bitmap_bytes(memslot);
+	kvm_arch_sync_dirty_log(kvm, *memslot);
+
+	n = kvm_dirty_bitmap_bytes(*memslot);
 
 	for (i = 0; !any && i < n/sizeof(long); ++i)
-		any = memslot->dirty_bitmap[i];
+		any = (*memslot)->dirty_bitmap[i];
 
-	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
+	if (copy_to_user(log->dirty_bitmap, (*memslot)->dirty_bitmap, n))
 		return -EFAULT;
 
 	if (any)
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 17/19] KVM: Terminate memslot walks via used_slots
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (15 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log() Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 18/19] KVM: Dynamically size memslot array based on number of used slots Sean Christopherson
                   ` (3 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Refactor memslot handling to treat the number of used slots as the de
facto size of the memslot array, e.g. return NULL from id_to_memslot()
when an invalid index is provided instead of relying on npages==0 to
detect an invalid memslot.  Rework the sorting and walking of memslots
in advance of dynamically sizing memslots to aid bisection and debug,
e.g. with luck, a bug in the refactoring will bisect here and/or hit a
WARN instead of randomly corrupting memory.

Alternatively, a global null/invalid memslot could be returned, i.e. so
callers of id_to_memslot() don't have to explicitly check for a NULL
memslot, but that approach runs the risk of introducing difficult-to-
debug issues, e.g. if the global null slot is modified.  Constifying
the return from id_to_memslot() to combat such issues is possible, but
would require a massive refactoring of arch specific code and would
still be susceptible to casting shenanigans.

Add function comments to update_memslots() and search_memslots() to
explicitly (and loudly) state how memslots are sorted.

No functional change intended.

Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/powerpc/kvm/book3s_hv.c |   2 +-
 arch/x86/kvm/x86.c           |  14 +--
 include/linux/kvm_host.h     |  18 ++-
 virt/kvm/arm/mmu.c           |   9 +-
 virt/kvm/kvm_main.c          | 220 ++++++++++++++++++++++++++---------
 5 files changed, 189 insertions(+), 74 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 04d5b7cf874f..c15cabb58e09 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -4410,7 +4410,7 @@ static int kvm_vm_ioctl_get_dirty_log_hv(struct kvm *kvm,
 	slots = kvm_memslots(kvm);
 	memslot = id_to_memslot(slots, log->slot);
 	r = -ENOENT;
-	if (!memslot->dirty_bitmap)
+	if (!memslot || !memslot->dirty_bitmap)
 		goto out;
 
 	/*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 87fca25d5217..39ba1de85575 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9532,9 +9532,9 @@ void kvm_arch_sync_events(struct kvm *kvm)
 int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
 {
 	int i, r;
-	unsigned long hva;
+	unsigned long hva, uninitialized_var(old_npages);
 	struct kvm_memslots *slots = kvm_memslots(kvm);
-	struct kvm_memory_slot *slot, old;
+	struct kvm_memory_slot *slot;
 
 	/* Called with kvm->slots_lock held.  */
 	if (WARN_ON(id >= KVM_MEM_SLOTS_NUM))
@@ -9542,7 +9542,7 @@ int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
 
 	slot = id_to_memslot(slots, id);
 	if (size) {
-		if (slot->npages)
+		if (slot && slot->npages)
 			return -EEXIST;
 
 		/*
@@ -9554,13 +9554,13 @@ int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
 		if (IS_ERR((void *)hva))
 			return PTR_ERR((void *)hva);
 	} else {
-		if (!slot->npages)
+		if (!slot || !slot->npages)
 			return 0;
 
-		hva = 0;
+		hva = slot->userspace_addr;
+		old_npages = slot->npages;
 	}
 
-	old = *slot;
 	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
 		struct kvm_userspace_memory_region m;
 
@@ -9575,7 +9575,7 @@ int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
 	}
 
 	if (!size)
-		vm_munmap(old.userspace_addr, old.npages * PAGE_SIZE);
+		vm_munmap(hva, old_npages * PAGE_SIZE);
 
 	return 0;
 }
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 7d666eedd203..49b6b457a157 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -574,10 +574,11 @@ static inline int kvm_vcpu_get_idx(struct kvm_vcpu *vcpu)
 	return vcpu->vcpu_idx;
 }
 
-#define kvm_for_each_memslot(memslot, slots)	\
-	for (memslot = &slots->memslots[0];	\
-	      memslot < slots->memslots + KVM_MEM_SLOTS_NUM && memslot->npages;\
-		memslot++)
+#define kvm_for_each_memslot(memslot, slots)				\
+	for (memslot = &slots->memslots[0];				\
+	     memslot < slots->memslots + slots->used_slots; memslot++)	\
+		if (WARN_ON_ONCE(!memslot->npages)) {			\
+		} else
 
 int kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id);
 void kvm_vcpu_uninit(struct kvm_vcpu *vcpu);
@@ -638,12 +639,15 @@ static inline struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu)
 	return __kvm_memslots(vcpu->kvm, as_id);
 }
 
-static inline struct kvm_memory_slot *
-id_to_memslot(struct kvm_memslots *slots, int id)
+static inline
+struct kvm_memory_slot *id_to_memslot(struct kvm_memslots *slots, int id)
 {
 	int index = slots->id_to_index[id];
 	struct kvm_memory_slot *slot;
 
+	if (index < 0)
+		return NULL;
+
 	slot = &slots->memslots[index];
 
 	WARN_ON(slot->id != id);
@@ -1013,6 +1017,8 @@ bool kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args);
  * used in non-modular code in arch/powerpc/kvm/book3s_hv_rm_mmu.c.
  * gfn_to_memslot() itself isn't here as an inline because that would
  * bloat other code too much.
+ *
+ * IMPORTANT: Slots are sorted from highest GFN to lowest GFN!
  */
 static inline struct kvm_memory_slot *
 search_memslots(struct kvm_memslots *slots, gfn_t gfn)
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index c49a3d5baad2..ae049c1033f3 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -1536,8 +1536,13 @@ void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot)
 {
 	struct kvm_memslots *slots = kvm_memslots(kvm);
 	struct kvm_memory_slot *memslot = id_to_memslot(slots, slot);
-	phys_addr_t start = memslot->base_gfn << PAGE_SHIFT;
-	phys_addr_t end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
+	phys_addr_t start, end;
+
+	if (WARN_ON_ONCE(!memslot))
+		return;
+
+	start = memslot->base_gfn << PAGE_SHIFT;
+	end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
 
 	spin_lock(&kvm->mmu_lock);
 	stage2_wp_range(kvm, start, end);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 999a2a0c83f5..a1566c5cee26 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -569,7 +569,7 @@ static struct kvm_memslots *kvm_alloc_memslots(void)
 		return NULL;
 
 	for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
-		slots->id_to_index[i] = slots->memslots[i].id = i;
+		slots->id_to_index[i] = slots->memslots[i].id = -1;
 
 	return slots;
 }
@@ -873,63 +873,162 @@ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot)
 }
 
 /*
- * Insert memslot and re-sort memslots based on their GFN,
- * so binary search could be used to lookup GFN.
- * Sorting algorithm takes advantage of having initially
- * sorted array and known changed memslot position.
+ * Delete a memslot by decrementing the number of used slots and shifting all
+ * other entries in the array forward one spot.
+ */
+static inline void kvm_memslot_delete(struct kvm_memslots *slots,
+				      struct kvm_memory_slot *memslot)
+{
+	struct kvm_memory_slot *mslots = slots->memslots;
+	int i;
+
+	if (WARN_ON(slots->id_to_index[memslot->id] == -1))
+		return;
+
+	slots->used_slots--;
+
+	for (i = slots->id_to_index[memslot->id]; i < slots->used_slots; i++) {
+		mslots[i] = mslots[i + 1];
+		slots->id_to_index[mslots[i].id] = i;
+	}
+	mslots[i] = *memslot;
+	slots->id_to_index[memslot->id] = -1;
+}
+
+/*
+ * "Insert" a new memslot by incrementing the number of used slots.  Returns
+ * the new slot's initial index into the memslots array.
+ */
+static inline int kvm_memslot_insert_back(struct kvm_memslots *slots)
+{
+	return slots->used_slots++;
+}
+
+/*
+ * Move a changed memslot backwards in the array by shifting existing slots
+ * with a higher GFN toward the front of the array.  Note, the changed memslot
+ * itself is not preserved in the array, i.e. not swapped at this time, only
+ * its new index into the array is tracked.  Returns the changed memslot's
+ * current index into the memslots array.
+ */
+static inline int kvm_memslot_move_backward(struct kvm_memslots *slots,
+					    struct kvm_memory_slot *memslot)
+{
+	struct kvm_memory_slot *mslots = slots->memslots;
+	int i;
+
+	if (WARN_ON_ONCE(slots->id_to_index[memslot->id] == -1) ||
+	    WARN_ON_ONCE(!slots->used_slots))
+		return -1;
+
+	/*
+	 * Move the target memslot backward in the array by shifting existing
+	 * memslots with a higher GFN (than the target memslot) towards the
+	 * front of the array.
+	 */
+	for (i = slots->id_to_index[memslot->id]; i < slots->used_slots - 1; i++) {
+		if (memslot->base_gfn > mslots[i + 1].base_gfn)
+			break;
+
+		WARN_ON_ONCE(memslot->base_gfn == mslots[i + 1].base_gfn);
+
+		/* Shift the next memslot forward one and update its index. */
+		mslots[i] = mslots[i + 1];
+		slots->id_to_index[mslots[i].id] = i;
+	}
+	return i;
+}
+
+/*
+ * Move a changed memslot forwards in the array by shifting existing slots with
+ * a lower GFN toward the back of the array.  Note, the changed memslot itself
+ * is not preserved in the array, i.e. not swapped at this time, only its new
+ * index into the array is tracked.  Returns the changed memslot's final index
+ * into the memslots array.
+ */
+static inline int kvm_memslot_move_forward(struct kvm_memslots *slots,
+					   struct kvm_memory_slot *memslot,
+					   int start)
+{
+	struct kvm_memory_slot *mslots = slots->memslots;
+	int i;
+
+	for (i = start; i > 0; i--) {
+		if (memslot->base_gfn < mslots[i - 1].base_gfn)
+			break;
+
+		WARN_ON_ONCE(memslot->base_gfn == mslots[i - 1].base_gfn);
+
+		/* Shift the next memslot back one and update its index. */
+		mslots[i] = mslots[i - 1];
+		slots->id_to_index[mslots[i].id] = i;
+	}
+	return i;
+}
+
+/*
+ * Re-sort memslots based on their GFN to account for an added, deleted, or
+ * moved memslot.  Sorting memslots by GFN allows using a binary search during
+ * memslot lookup.
+ *
+ * IMPORTANT: Slots are sorted from highest GFN to lowest GFN!  I.e. the entry
+ * at memslots[0] has the highest GFN.
+ *
+ * The sorting algorithm takes advantage of having initially sorted memslots
+ * and knowing the position of the changed memslot.  Sorting is also optimized
+ * by not swapping the updated memslot and instead only shifting other memslots
+ * and tracking the new index for the update memslot.  Only once its final
+ * index is known is the updated memslot copied into its position in the array.
+ *
+ *  - When deleting a memslot, the deleted memslot simply needs to be moved to
+ *    the end of the array.
+ *
+ *  - When creating a memslot, the algorithm "inserts" the new memslot at the
+ *    end of the array and then it forward to its correct location.
+ *
+ *  - When moving a memslot, the algorithm first moves the updated memslot
+ *    backward to handle the scenario where the memslot's GFN was changed to a
+ *    lower value.  update_memslots() then falls through and runs the same flow
+ *    as creating a memslot to move the memslot forward to handle the scenario
+ *    where its GFN was changed to a higher value.
+ *
+ * Note, slots are sorted from highest->lowest instead of lowest->highest for
+ * historical reasons.  Originally, invalid memslots where denoted by having
+ * GFN=0, thus sorting from highest->lowest naturally sorted invalid memslots
+ * to the end of the array.  The current algorithm uses dedicated logic to
+ * delete a memslot and thus does not rely on invalid memslots having GFN=0.
+ *
+ * The other historical motiviation for highest->lowest was to improve the
+ * performance of memslot lookup.  KVM originally used a linear search starting
+ * at memslots[0].  On x86, the largest memslot usually has one of the highest,
+ * if not *the* highest, GFN, as the bulk of the guest's RAM is located in a
+ * single memslot above the 4gb boundary.  As the largest memslot is also the
+ * most likely to be referenced, sorting it to the front of the array was
+ * advantageous.  The current binary search starts from the middle of the array
+ * and uses an LRU pointer to improve performance for all memslots and GFNs.
  */
 static void update_memslots(struct kvm_memslots *slots,
-			    struct kvm_memory_slot *new,
+			    struct kvm_memory_slot *memslot,
 			    enum kvm_mr_change change)
 {
-	int id = new->id;
-	int i = slots->id_to_index[id];
-	struct kvm_memory_slot *mslots = slots->memslots;
+	int i;
 
-	WARN_ON(mslots[i].id != id);
-	switch (change) {
-	case KVM_MR_CREATE:
-		slots->used_slots++;
-		WARN_ON(mslots[i].npages || !new->npages);
-		break;
-	case KVM_MR_DELETE:
-		slots->used_slots--;
-		WARN_ON(new->npages || !mslots[i].npages);
-		break;
-	default:
-		break;
-	}
+	if (change == KVM_MR_DELETE) {
+		kvm_memslot_delete(slots, memslot);
+	} else {
+		if (change == KVM_MR_CREATE)
+			i = kvm_memslot_insert_back(slots);
+		else
+			i = kvm_memslot_move_backward(slots, memslot);
+		i = kvm_memslot_move_forward(slots, memslot, i);
 
-	while (i < KVM_MEM_SLOTS_NUM - 1 &&
-	       new->base_gfn <= mslots[i + 1].base_gfn) {
-		if (!mslots[i + 1].npages)
-			break;
-		mslots[i] = mslots[i + 1];
-		slots->id_to_index[mslots[i].id] = i;
-		i++;
+		/*
+		 * Copy the memslot to its new position in memslots and update
+		 * its index accordingly.
+		 */
+		slots->memslots[i] = *memslot;
+		slots->id_to_index[memslot->id] = i;
 	}
-
-	/*
-	 * The ">=" is needed when creating a slot with base_gfn == 0,
-	 * so that it moves before all those with base_gfn == npages == 0.
-	 *
-	 * On the other hand, if new->npages is zero, the above loop has
-	 * already left i pointing to the beginning of the empty part of
-	 * mslots, and the ">=" would move the hole backwards in this
-	 * case---which is wrong.  So skip the loop when deleting a slot.
-	 */
-	if (new->npages) {
-		while (i > 0 &&
-		       new->base_gfn >= mslots[i - 1].base_gfn) {
-			mslots[i] = mslots[i - 1];
-			slots->id_to_index[mslots[i].id] = i;
-			i--;
-		}
-	} else
-		WARN_ON_ONCE(i != slots->used_slots);
-
-	mslots[i] = *new;
-	slots->id_to_index[mslots[i].id] = i;
 }
 
 static int check_memory_region_flags(const struct kvm_userspace_memory_region *mem)
@@ -1108,8 +1207,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	 * when the memslots are re-sorted by update_memslots().
 	 */
 	tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id);
-	old = *tmp;
-	tmp = NULL;
+	if (tmp) {
+		old = *tmp;
+		tmp = NULL;
+	} else {
+		memset(&old, 0, sizeof(old));
+		old.id = id;
+	}
 
 	if (!mem->memory_size)
 		return kvm_delete_memslot(kvm, mem, &old, as_id);
@@ -1227,7 +1331,7 @@ int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
 
 	slots = __kvm_memslots(kvm, as_id);
 	*memslot = id_to_memslot(slots, id);
-	if (!(*memslot)->dirty_bitmap)
+	if (!(*memslot) || !(*memslot)->dirty_bitmap)
 		return -ENOENT;
 
 	kvm_arch_sync_dirty_log(kvm, *memslot);
@@ -1285,10 +1389,10 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log)
 
 	slots = __kvm_memslots(kvm, as_id);
 	memslot = id_to_memslot(slots, id);
+	if (!memslot || !memslot->dirty_bitmap)
+		return -ENOENT;
 
 	dirty_bitmap = memslot->dirty_bitmap;
-	if (!dirty_bitmap)
-		return -ENOENT;
 
 	kvm_arch_sync_dirty_log(kvm, memslot);
 
@@ -1396,10 +1500,10 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm,
 
 	slots = __kvm_memslots(kvm, as_id);
 	memslot = id_to_memslot(slots, id);
+	if (!memslot || !memslot->dirty_bitmap)
+		return -ENOENT;
 
 	dirty_bitmap = memslot->dirty_bitmap;
-	if (!dirty_bitmap)
-		return -ENOENT;
 
 	n = ALIGN(log->num_pages, BITS_PER_LONG) / 8;
 
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 18/19] KVM: Dynamically size memslot array based on number of used slots
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (16 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 17/19] KVM: Terminate memslot walks via used_slots Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-17 20:40 ` [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION Sean Christopherson
                   ` (2 subsequent siblings)
  20 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Now that the memslot logic doesn't assume memslots are always non-NULL,
dynamically size the array of memslots instead of unconditionally
allocating memory for the maximum number of memslots.

Note, because a to-be-deleted memslot must first be invalidated, the
array size cannot be immediately reduced when deleting a memslot.
However, consecutive deletions will realize the memory savings, i.e.
a second deletion will trim the entry.

Tested-by: Christoffer Dall <christoffer.dall@arm.com>
Tested-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 include/linux/kvm_host.h |  2 +-
 virt/kvm/kvm_main.c      | 31 ++++++++++++++++++++++++++++---
 2 files changed, 29 insertions(+), 4 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 49b6b457a157..eecfa1fe0fc7 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -433,11 +433,11 @@ static inline int kvm_arch_vcpu_memslots_id(struct kvm_vcpu *vcpu)
  */
 struct kvm_memslots {
 	u64 generation;
-	struct kvm_memory_slot memslots[KVM_MEM_SLOTS_NUM];
 	/* The mapping table from slot id to the index in memslots[]. */
 	short id_to_index[KVM_MEM_SLOTS_NUM];
 	atomic_t lru_slot;
 	int used_slots;
+	struct kvm_memory_slot memslots[];
 };
 
 struct kvm {
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a1566c5cee26..57926579551b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -569,7 +569,7 @@ static struct kvm_memslots *kvm_alloc_memslots(void)
 		return NULL;
 
 	for (i = 0; i < KVM_MEM_SLOTS_NUM; i++)
-		slots->id_to_index[i] = slots->memslots[i].id = -1;
+		slots->id_to_index[i] = -1;
 
 	return slots;
 }
@@ -1081,6 +1081,32 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
 	return old_memslots;
 }
 
+/*
+ * Note, at a minimum, the current number of used slots must be allocated, even
+ * when deleting a memslot, as we need a complete duplicate of the memslots for
+ * use when invalidating a memslot prior to deleting/moving the memslot.
+ */
+static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old,
+					     enum kvm_mr_change change)
+{
+	struct kvm_memslots *slots;
+	size_t old_size, new_size;
+
+	old_size = sizeof(struct kvm_memslots) +
+		   (sizeof(struct kvm_memory_slot) * old->used_slots);
+
+	if (change == KVM_MR_CREATE)
+		new_size = old_size + sizeof(struct kvm_memory_slot);
+	else
+		new_size = old_size;
+
+	slots = kvzalloc(new_size, GFP_KERNEL_ACCOUNT);
+	if (likely(slots))
+		memcpy(slots, old, old_size);
+
+	return slots;
+}
+
 static int kvm_set_memslot(struct kvm *kvm,
 			   const struct kvm_userspace_memory_region *mem,
 			   struct kvm_memory_slot *old,
@@ -1091,10 +1117,9 @@ static int kvm_set_memslot(struct kvm *kvm,
 	struct kvm_memslots *slots;
 	int r;
 
-	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
+	slots = kvm_dup_memslots(__kvm_memslots(kvm, as_id), change);
 	if (!slots)
 		return -ENOMEM;
-	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
 
 	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
 		/*
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (17 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 18/19] KVM: Dynamically size memslot array based on number of used slots Sean Christopherson
@ 2019-12-17 20:40 ` Sean Christopherson
  2019-12-18 11:29   ` Christian Borntraeger
  2019-12-18 11:39   ` Christian Borntraeger
  2019-12-18 11:40 ` [PATCH v4 00/19] KVM: Dynamically size memslot arrays Christian Borntraeger
  2019-12-18 18:10 ` Marc Zyngier
  20 siblings, 2 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:40 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Sean Christopherson,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

Add a KVM selftest to test moving the base gfn of a userspace memory
region.  The test is primarily targeted at x86 to verify its memslot
metadata is correctly updated, but also provides basic functionality
coverage on other architectures.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   3 +
 .../testing/selftests/kvm/include/kvm_util.h  |   1 +
 tools/testing/selftests/kvm/lib/kvm_util.c    |  30 ++++
 .../selftests/kvm/set_memory_region_test.c    | 142 ++++++++++++++++++
 5 files changed, 177 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/set_memory_region_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 30072c3f52fb..6f60ceb81440 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -17,3 +17,4 @@
 /clear_dirty_log_test
 /dirty_log_test
 /kvm_create_max_vcpus
+/set_memory_region_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 3138a916574a..01c79e02c5b7 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -29,15 +29,18 @@ TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
 TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
 TEST_GEN_PROGS_x86_64 += dirty_log_test
 TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
+TEST_GEN_PROGS_x86_64 += set_memory_region_test
 
 TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
 TEST_GEN_PROGS_aarch64 += dirty_log_test
 TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
+TEST_GEN_PROGS_aarch64 += set_memory_region_test
 
 TEST_GEN_PROGS_s390x = s390x/memop
 TEST_GEN_PROGS_s390x += s390x/sync_regs_test
 TEST_GEN_PROGS_s390x += dirty_log_test
 TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
+TEST_GEN_PROGS_s390x += set_memory_region_test
 
 TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
 LIBKVM += $(LIBKVM_$(UNAME_M))
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 29cccaf96baf..15d3b8690ffb 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -100,6 +100,7 @@ int _vcpu_ioctl(struct kvm_vm *vm, uint32_t vcpuid, unsigned long ioctl,
 		void *arg);
 void vm_ioctl(struct kvm_vm *vm, unsigned long ioctl, void *arg);
 void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags);
+void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
 void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid);
 vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
 			  uint32_t data_memslot, uint32_t pgd_memslot);
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 41cf45416060..464a75ce9843 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -756,6 +756,36 @@ void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags)
 		ret, errno, slot, flags);
 }
 
+/*
+ * VM Memory Region Move
+ *
+ * Input Args:
+ *   vm - Virtual Machine
+ *   slot - Slot of the memory region to move
+ *   flags - Starting guest physical address
+ *
+ * Output Args: None
+ *
+ * Return: None
+ *
+ * Change the gpa of a memory region.
+ */
+void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa)
+{
+	struct userspace_mem_region *region;
+	int ret;
+
+	region = memslot2region(vm, slot);
+
+	region->region.guest_phys_addr = new_gpa;
+
+	ret = ioctl(vm->fd, KVM_SET_USER_MEMORY_REGION, &region->region);
+
+	TEST_ASSERT(!ret, "KVM_SET_USER_MEMORY_REGION failed\n"
+		    "ret: %i errno: %i slot: %u flags: 0x%x",
+		    ret, errno, slot, new_gpa);
+}
+
 /*
  * VCPU mmap Size
  *
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
new file mode 100644
index 000000000000..c9603b95ccf7
--- /dev/null
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <pthread.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include <linux/compiler.h>
+
+#include <test_util.h>
+#include <kvm_util.h>
+#include <processor.h>
+
+#define VCPU_ID 0
+
+/*
+ * Somewhat arbitrary location and slot, intended to not overlap anything.  The
+ * location and size are specifically 2mb sized/aligned so that the initial
+ * region corresponds to exactly one large page (on x86 and arm64).
+ */
+#define MEM_REGION_GPA		0xc0000000
+#define MEM_REGION_SIZE		0x200000
+#define MEM_REGION_SLOT		10
+
+static void guest_code(void)
+{
+	uint64_t val;
+
+	do {
+		val = READ_ONCE(*((uint64_t *)MEM_REGION_GPA));
+	} while (!val);
+
+	if (val != 1)
+		ucall(UCALL_ABORT, 1, val);
+
+	GUEST_DONE();
+}
+
+static void *vcpu_worker(void *data)
+{
+	struct kvm_vm *vm = data;
+	struct kvm_run *run;
+	struct ucall uc;
+	uint64_t cmd;
+
+	/*
+	 * Loop until the guest is done.  Re-enter the guest on all MMIO exits,
+	 * which will occur if the guest attempts to access a memslot while it
+	 * is being moved.
+	 */
+	run = vcpu_state(vm, VCPU_ID);
+	do {
+		vcpu_run(vm, VCPU_ID);
+	} while (run->exit_reason == KVM_EXIT_MMIO);
+
+	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+		    "Unexpected exit reason = %d", run->exit_reason);
+
+	cmd = get_ucall(vm, VCPU_ID, &uc);
+	TEST_ASSERT(cmd == UCALL_DONE, "Unexpected val in guest = %llu",
+		    uc.args[0]);
+	return NULL;
+}
+
+static void test_move_memory_region(void)
+{
+	pthread_t vcpu_thread;
+	struct kvm_vm *vm;
+	uint64_t *hva;
+	uint64_t gpa;
+
+	vm = vm_create_default(VCPU_ID, 0, guest_code);
+
+	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_THP,
+				    MEM_REGION_GPA, MEM_REGION_SLOT,
+				    MEM_REGION_SIZE / getpagesize(), 0);
+
+	/*
+	 * Allocate and map two pages so that the GPA accessed by guest_code()
+	 * stays valid across the memslot move.
+	 */
+	gpa = vm_phy_pages_alloc(vm, 2, MEM_REGION_GPA, MEM_REGION_SLOT);
+	TEST_ASSERT(gpa == MEM_REGION_GPA, "Failed vm_phy_pages_alloc\n");
+
+	virt_map(vm, MEM_REGION_GPA, MEM_REGION_GPA, 2 * 4096, 0);
+
+	/* Ditto for the host mapping so that both pages can be zeroed. */
+	hva = addr_gpa2hva(vm, MEM_REGION_GPA);
+	memset(hva, 0, 2 * 4096);
+
+	pthread_create(&vcpu_thread, NULL, vcpu_worker, vm);
+
+	/* Ensure the guest thread is spun up. */
+	usleep(100000);
+
+	/*
+	 * Shift the region's base GPA.  The guest should not see "2" as the
+	 * hva->gpa translation is misaligned, i.e. the guest is accessing a
+	 * different host pfn.
+	 */
+	vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA - 4096);
+	WRITE_ONCE(*hva, 2);
+
+	usleep(100000);
+
+	/*
+	 * Note, value in memory needs to be changed *before* restoring the
+	 * memslot, else the guest could race the update and see "2".
+	 */
+	WRITE_ONCE(*hva, 1);
+
+	/* Restore the original base, the guest should see "1". */
+	vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA);
+
+	pthread_join(vcpu_thread, NULL);
+
+	kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+	int i, loops;
+
+	/* Tell stdout not to buffer its content */
+	setbuf(stdout, NULL);
+
+	if (argc > 1)
+		loops = atoi(argv[1]);
+	else
+		loops = 10;
+
+	for (i = 0; i < loops; i++)
+		test_move_memory_region();
+
+	return 0;
+}
-- 
2.24.1


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot
  2019-12-17 20:40 ` [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
@ 2019-12-17 20:48   ` Sean Christopherson
  2019-12-17 20:50     ` Sean Christopherson
  2019-12-17 21:56   ` Peter Xu
  1 sibling, 1 reply; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:48 UTC (permalink / raw)
  To: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Vitaly Kuznetsov, Wanpeng Li,
	Jim Mattson, Joerg Roedel, James Morse, Julien Thierry,
	Suzuki K Poulose, linux-mips, kvm-ppc, kvm, linux-arm-kernel,
	kvmarm, linux-kernel, Christoffer Dall,
	Philippe Mathieu-Daudé

Dropping non-x86 folks...

This should be included in 5.5 if possible even though the bug has existed
for over a decade.  It's trivially easy for a malicious userspace to
crash KVM and hang the host.  Depending how userspace VMM behavior, it may
even be possible to trigger from a guest.

On Tue, Dec 17, 2019 at 12:40:23PM -0800, Sean Christopherson wrote:
> Reallocate a rmap array and recalcuate large page compatibility when
> moving an existing memslot to correctly handle the alignment properties
> of the new memslot.  The number of rmap entries required at each level
> is dependent on the alignment of the memslot's base gfn with respect to
> that level, e.g. moving a large-page aligned memslot so that it becomes
> unaligned will increase the number of rmap entries needed at the now
> unaligned level.
> 
> Not updating the rmap array is the most obvious bug, as KVM accesses
> garbage data beyond the end of the rmap.  KVM interprets the bad data as
> pointers, leading to non-canonical #GPs, unexpected #PFs, etc...
> 
>   general protection fault: 0000 [#1] SMP
>   CPU: 0 PID: 1909 Comm: move_memory_reg Not tainted 5.4.0-rc7+ #139
>   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>   RIP: 0010:rmap_get_first+0x37/0x50 [kvm]
>   Code: <48> 8b 3b 48 85 ff 74 ec e8 6c f4 ff ff 85 c0 74 e3 48 89 d8 5b c3
>   RSP: 0018:ffffc9000021bbc8 EFLAGS: 00010246
>   RAX: ffff00617461642e RBX: ffff00617461642e RCX: 0000000000000012
>   RDX: ffff88827400f568 RSI: ffffc9000021bbe0 RDI: ffff88827400f570
>   RBP: 0010000000000000 R08: ffffc9000021bd00 R09: ffffc9000021bda8
>   R10: ffffc9000021bc48 R11: 0000000000000000 R12: 0030000000000000
>   R13: 0000000000000000 R14: ffff88827427d700 R15: ffffc9000021bce8
>   FS:  00007f7eda014700(0000) GS:ffff888277a00000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 00007f7ed9216ff8 CR3: 0000000274391003 CR4: 0000000000162eb0
>   Call Trace:
>    kvm_mmu_slot_set_dirty+0xa1/0x150 [kvm]
>    __kvm_set_memory_region.part.64+0x559/0x960 [kvm]
>    kvm_set_memory_region+0x45/0x60 [kvm]
>    kvm_vm_ioctl+0x30f/0x920 [kvm]
>    do_vfs_ioctl+0xa1/0x620
>    ksys_ioctl+0x66/0x70
>    __x64_sys_ioctl+0x16/0x20
>    do_syscall_64+0x4c/0x170
>    entry_SYSCALL_64_after_hwframe+0x44/0xa9
>   RIP: 0033:0x7f7ed9911f47
>   Code: <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 21 6f 2c 00 f7 d8 64 89 01 48
>   RSP: 002b:00007ffc00937498 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>   RAX: ffffffffffffffda RBX: 0000000001ab0010 RCX: 00007f7ed9911f47
>   RDX: 0000000001ab1350 RSI: 000000004020ae46 RDI: 0000000000000004
>   RBP: 000000000000000a R08: 0000000000000000 R09: 00007f7ed9214700
>   R10: 00007f7ed92149d0 R11: 0000000000000246 R12: 00000000bffff000
>   R13: 0000000000000003 R14: 00007f7ed9215000 R15: 0000000000000000
>   Modules linked in: kvm_intel kvm irqbypass
>   ---[ end trace 0c5f570b3358ca89 ]---
> 
> The disallow_lpage tracking is more subtle.  Failure to update results
> in KVM creating large pages when it shouldn't, either due to stale data
> or again due to indexing beyond the end of the metadata arrays, which
> can lead to memory corruption and/or leaking data to guest/userspace.
> 
> Note, the arrays for the old memslot are freed by the unconditional call
> to kvm_free_memslot() in __kvm_set_memory_region().
> 
> Fixes: 05da45583de9b ("KVM: MMU: large page support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  arch/x86/kvm/x86.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 8bb2fb1705ff..04d1bf89da0e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9703,6 +9703,13 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
>  {
>  	int i;
>  
> +	/*
> +	 * Clear out the previous array pointers for the KVM_MR_MOVE case.  The
> +	 * old arrays will be freed by __kvm_set_memory_region() if installing
> +	 * the new memslot is successful.
> +	 */
> +	memset(&slot->arch, 0, sizeof(slot->arch));
> +
>  	for (i = 0; i < KVM_NR_PAGE_SIZES; ++i) {
>  		struct kvm_lpage_info *linfo;
>  		unsigned long ugfn;
> @@ -9777,6 +9784,10 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
>  				const struct kvm_userspace_memory_region *mem,
>  				enum kvm_mr_change change)
>  {
> +	if (change == KVM_MR_MOVE)
> +		return kvm_arch_create_memslot(kvm, memslot,
> +					       mem->memory_size >> PAGE_SHIFT);
> +
>  	return 0;
>  }
>  
> -- 
> 2.24.1
> 

^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot
  2019-12-17 20:48   ` Sean Christopherson
@ 2019-12-17 20:50     ` Sean Christopherson
  0 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 20:50 UTC (permalink / raw)
  To: Paolo Bonzini
  Cc: Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel, kvm

*sigh*

Actually trimming this to x86 people.  Darn 'y' and 't' keys are too close
together.

On Tue, Dec 17, 2019 at 12:48:22PM -0800, Sean Christopherson wrote:
> Dropping non-x86 folks...
> 
> This should be included in 5.5 if possible even though the bug has existed
> for over a decade.  It's trivially easy for a malicious userspace to
> crash KVM and hang the host.  Depending how userspace VMM behavior, it may
> even be possible to trigger from a guest.
> 
> On Tue, Dec 17, 2019 at 12:40:23PM -0800, Sean Christopherson wrote:
> > Reallocate a rmap array and recalcuate large page compatibility when
> > moving an existing memslot to correctly handle the alignment properties
> > of the new memslot.  The number of rmap entries required at each level
> > is dependent on the alignment of the memslot's base gfn with respect to
> > that level, e.g. moving a large-page aligned memslot so that it becomes
> > unaligned will increase the number of rmap entries needed at the now
> > unaligned level.
> > 
> > Not updating the rmap array is the most obvious bug, as KVM accesses
> > garbage data beyond the end of the rmap.  KVM interprets the bad data as
> > pointers, leading to non-canonical #GPs, unexpected #PFs, etc...
> > 
> >   general protection fault: 0000 [#1] SMP
> >   CPU: 0 PID: 1909 Comm: move_memory_reg Not tainted 5.4.0-rc7+ #139
> >   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
> >   RIP: 0010:rmap_get_first+0x37/0x50 [kvm]
> >   Code: <48> 8b 3b 48 85 ff 74 ec e8 6c f4 ff ff 85 c0 74 e3 48 89 d8 5b c3
> >   RSP: 0018:ffffc9000021bbc8 EFLAGS: 00010246
> >   RAX: ffff00617461642e RBX: ffff00617461642e RCX: 0000000000000012
> >   RDX: ffff88827400f568 RSI: ffffc9000021bbe0 RDI: ffff88827400f570
> >   RBP: 0010000000000000 R08: ffffc9000021bd00 R09: ffffc9000021bda8
> >   R10: ffffc9000021bc48 R11: 0000000000000000 R12: 0030000000000000
> >   R13: 0000000000000000 R14: ffff88827427d700 R15: ffffc9000021bce8
> >   FS:  00007f7eda014700(0000) GS:ffff888277a00000(0000) knlGS:0000000000000000
> >   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> >   CR2: 00007f7ed9216ff8 CR3: 0000000274391003 CR4: 0000000000162eb0
> >   Call Trace:
> >    kvm_mmu_slot_set_dirty+0xa1/0x150 [kvm]
> >    __kvm_set_memory_region.part.64+0x559/0x960 [kvm]
> >    kvm_set_memory_region+0x45/0x60 [kvm]
> >    kvm_vm_ioctl+0x30f/0x920 [kvm]
> >    do_vfs_ioctl+0xa1/0x620
> >    ksys_ioctl+0x66/0x70
> >    __x64_sys_ioctl+0x16/0x20
> >    do_syscall_64+0x4c/0x170
> >    entry_SYSCALL_64_after_hwframe+0x44/0xa9
> >   RIP: 0033:0x7f7ed9911f47
> >   Code: <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 21 6f 2c 00 f7 d8 64 89 01 48
> >   RSP: 002b:00007ffc00937498 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> >   RAX: ffffffffffffffda RBX: 0000000001ab0010 RCX: 00007f7ed9911f47
> >   RDX: 0000000001ab1350 RSI: 000000004020ae46 RDI: 0000000000000004
> >   RBP: 000000000000000a R08: 0000000000000000 R09: 00007f7ed9214700
> >   R10: 00007f7ed92149d0 R11: 0000000000000246 R12: 00000000bffff000
> >   R13: 0000000000000003 R14: 00007f7ed9215000 R15: 0000000000000000
> >   Modules linked in: kvm_intel kvm irqbypass
> >   ---[ end trace 0c5f570b3358ca89 ]---
> > 
> > The disallow_lpage tracking is more subtle.  Failure to update results
> > in KVM creating large pages when it shouldn't, either due to stale data
> > or again due to indexing beyond the end of the metadata arrays, which
> > can lead to memory corruption and/or leaking data to guest/userspace.
> > 
> > Note, the arrays for the old memslot are freed by the unconditional call
> > to kvm_free_memslot() in __kvm_set_memory_region().
> > 
> > Fixes: 05da45583de9b ("KVM: MMU: large page support")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > ---
> >  arch/x86/kvm/x86.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> > 
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 8bb2fb1705ff..04d1bf89da0e 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -9703,6 +9703,13 @@ int kvm_arch_create_memslot(struct kvm *kvm, struct kvm_memory_slot *slot,
> >  {
> >  	int i;
> >  
> > +	/*
> > +	 * Clear out the previous array pointers for the KVM_MR_MOVE case.  The
> > +	 * old arrays will be freed by __kvm_set_memory_region() if installing
> > +	 * the new memslot is successful.
> > +	 */
> > +	memset(&slot->arch, 0, sizeof(slot->arch));
> > +
> >  	for (i = 0; i < KVM_NR_PAGE_SIZES; ++i) {
> >  		struct kvm_lpage_info *linfo;
> >  		unsigned long ugfn;
> > @@ -9777,6 +9784,10 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm,
> >  				const struct kvm_userspace_memory_region *mem,
> >  				enum kvm_mr_change change)
> >  {
> > +	if (change == KVM_MR_MOVE)
> > +		return kvm_arch_create_memslot(kvm, memslot,
> > +					       mem->memory_size >> PAGE_SHIFT);
> > +
> >  	return 0;
> >  }
> >  
> > -- 
> > 2.24.1
> > 

^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot
  2019-12-17 20:40 ` [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
  2019-12-17 20:48   ` Sean Christopherson
@ 2019-12-17 21:56   ` Peter Xu
  2019-12-17 22:20     ` Sean Christopherson
  1 sibling, 1 reply; 37+ messages in thread
From: Peter Xu @ 2019-12-17 21:56 UTC (permalink / raw)
  To: Sean Christopherson
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson,
	David Gibson

On Tue, Dec 17, 2019 at 12:40:23PM -0800, Sean Christopherson wrote:
> Reallocate a rmap array and recalcuate large page compatibility when
> moving an existing memslot to correctly handle the alignment properties
> of the new memslot.  The number of rmap entries required at each level
> is dependent on the alignment of the memslot's base gfn with respect to
> that level, e.g. moving a large-page aligned memslot so that it becomes
> unaligned will increase the number of rmap entries needed at the now
> unaligned level.
> 
> Not updating the rmap array is the most obvious bug, as KVM accesses
> garbage data beyond the end of the rmap.  KVM interprets the bad data as
> pointers, leading to non-canonical #GPs, unexpected #PFs, etc...
> 
>   general protection fault: 0000 [#1] SMP
>   CPU: 0 PID: 1909 Comm: move_memory_reg Not tainted 5.4.0-rc7+ #139
>   Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
>   RIP: 0010:rmap_get_first+0x37/0x50 [kvm]
>   Code: <48> 8b 3b 48 85 ff 74 ec e8 6c f4 ff ff 85 c0 74 e3 48 89 d8 5b c3
>   RSP: 0018:ffffc9000021bbc8 EFLAGS: 00010246
>   RAX: ffff00617461642e RBX: ffff00617461642e RCX: 0000000000000012
>   RDX: ffff88827400f568 RSI: ffffc9000021bbe0 RDI: ffff88827400f570
>   RBP: 0010000000000000 R08: ffffc9000021bd00 R09: ffffc9000021bda8
>   R10: ffffc9000021bc48 R11: 0000000000000000 R12: 0030000000000000
>   R13: 0000000000000000 R14: ffff88827427d700 R15: ffffc9000021bce8
>   FS:  00007f7eda014700(0000) GS:ffff888277a00000(0000) knlGS:0000000000000000
>   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>   CR2: 00007f7ed9216ff8 CR3: 0000000274391003 CR4: 0000000000162eb0
>   Call Trace:
>    kvm_mmu_slot_set_dirty+0xa1/0x150 [kvm]
>    __kvm_set_memory_region.part.64+0x559/0x960 [kvm]
>    kvm_set_memory_region+0x45/0x60 [kvm]
>    kvm_vm_ioctl+0x30f/0x920 [kvm]
>    do_vfs_ioctl+0xa1/0x620
>    ksys_ioctl+0x66/0x70
>    __x64_sys_ioctl+0x16/0x20
>    do_syscall_64+0x4c/0x170
>    entry_SYSCALL_64_after_hwframe+0x44/0xa9
>   RIP: 0033:0x7f7ed9911f47
>   Code: <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 21 6f 2c 00 f7 d8 64 89 01 48
>   RSP: 002b:00007ffc00937498 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>   RAX: ffffffffffffffda RBX: 0000000001ab0010 RCX: 00007f7ed9911f47
>   RDX: 0000000001ab1350 RSI: 000000004020ae46 RDI: 0000000000000004
>   RBP: 000000000000000a R08: 0000000000000000 R09: 00007f7ed9214700
>   R10: 00007f7ed92149d0 R11: 0000000000000246 R12: 00000000bffff000
>   R13: 0000000000000003 R14: 00007f7ed9215000 R15: 0000000000000000
>   Modules linked in: kvm_intel kvm irqbypass
>   ---[ end trace 0c5f570b3358ca89 ]---
> 
> The disallow_lpage tracking is more subtle.  Failure to update results
> in KVM creating large pages when it shouldn't, either due to stale data
> or again due to indexing beyond the end of the metadata arrays, which
> can lead to memory corruption and/or leaking data to guest/userspace.
> 
> Note, the arrays for the old memslot are freed by the unconditional call
> to kvm_free_memslot() in __kvm_set_memory_region().
> 
> Fixes: 05da45583de9b ("KVM: MMU: large page support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

I think the error-prone part is:

	new = old = *slot;

Where IMHO it would be better if we only copy pointers explicitly when
under control, rather than blindly copying all the pointers in the
structure which even contains sub-structures.

For example, I see PPC has this:

struct kvm_arch_memory_slot {
#ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
	unsigned long *rmap;
#endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
};

I started to look into HV code of it a bit, then I see...

 - kvm_arch_create_memslot(kvmppc_core_create_memslot_hv) init slot->arch.rmap,
 - kvm_arch_flush_shadow_memslot(kvmppc_core_flush_memslot_hv) didn't free it,
 - kvm_arch_prepare_memory_region(kvmppc_core_prepare_memory_region_hv) is nop.

So Does it have similar issue?

-- 
Peter Xu


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 05/19] KVM: x86: Allocate memslot resources during prepare_memory_region()
  2019-12-17 20:40 ` [PATCH v4 05/19] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
@ 2019-12-17 22:07   ` Peter Xu
  0 siblings, 0 replies; 37+ messages in thread
From: Peter Xu @ 2019-12-17 22:07 UTC (permalink / raw)
  To: Sean Christopherson
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson

On Tue, Dec 17, 2019 at 12:40:27PM -0800, Sean Christopherson wrote:
> Allocate the various metadata structures associated with a new memslot
> during kvm_arch_prepare_memory_region(), which paves the way for
> removing kvm_arch_create_memslot() altogether.  Moving x86's memory
> allocation only changes the order of kernel memory allocations between
> x86 and common KVM code.
> 
> No functional change intended.

(I still think it's a functional change, though...)

> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot
  2019-12-17 21:56   ` Peter Xu
@ 2019-12-17 22:20     ` Sean Christopherson
  2019-12-17 22:37       ` Peter Xu
  0 siblings, 1 reply; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 22:20 UTC (permalink / raw)
  To: Peter Xu
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson,
	David Gibson

On Tue, Dec 17, 2019 at 04:56:40PM -0500, Peter Xu wrote:
> On Tue, Dec 17, 2019 at 12:40:23PM -0800, Sean Christopherson wrote:
> > Reallocate a rmap array and recalcuate large page compatibility when
> > moving an existing memslot to correctly handle the alignment properties
> > of the new memslot.  The number of rmap entries required at each level
> > is dependent on the alignment of the memslot's base gfn with respect to
> > that level, e.g. moving a large-page aligned memslot so that it becomes
> > unaligned will increase the number of rmap entries needed at the now
> > unaligned level.

...

> I think the error-prone part is:
> 
> 	new = old = *slot;

Lol, IMO the error-prone part is the entire memslot mess :-)

> Where IMHO it would be better if we only copy pointers explicitly when
> under control, rather than blindly copying all the pointers in the
> structure which even contains sub-structures.

Long term, yes, that would be ideal.  For the immediate bug fix, reworking
common KVM and other arch code would be unnecessarily dangerous and would
make it more difficult to backport the fix to stable branches.

I actually briefly considered moving the slot->arch handling into arch
code as part of the bug fix, but the memslot code has many subtle
dependencies, e.g. PPC and x86 rely on common KVM code to copy slot->arch
when flags are being changed.

I'll happily clean up the slot->arch code once this series is merged.
There is refactoring in this series that will make it a lot easier to do
additional clean up.

> For example, I see PPC has this:
> 
> struct kvm_arch_memory_slot {
> #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
> 	unsigned long *rmap;
> #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
> };
> 
> I started to look into HV code of it a bit, then I see...
> 
>  - kvm_arch_create_memslot(kvmppc_core_create_memslot_hv) init slot->arch.rmap,
>  - kvm_arch_flush_shadow_memslot(kvmppc_core_flush_memslot_hv) didn't free it,
>  - kvm_arch_prepare_memory_region(kvmppc_core_prepare_memory_region_hv) is nop.
> 
> So Does it have similar issue?

No, KVM doesn't allow a memslot's size to be changed, and PPC's rmap
allocation is directly tied to the size of the memslot.  The x86 bug exists
because the size of its metadata arrays varies based on the alignment of
the base gfn.

^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap
  2019-12-17 20:40 ` [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
@ 2019-12-17 22:24   ` Peter Xu
  2019-12-17 22:51     ` Sean Christopherson
  0 siblings, 1 reply; 37+ messages in thread
From: Peter Xu @ 2019-12-17 22:24 UTC (permalink / raw)
  To: Sean Christopherson
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson

On Tue, Dec 17, 2019 at 12:40:29PM -0800, Sean Christopherson wrote:
> Explicitly free an allocated-but-unused dirty bitmap instead of relying
> on kvm_free_memslot() if an error occurs in __kvm_set_memory_region().
> There is no longer a need to abuse kvm_free_memslot() to free arch
> specific resources as arch specific code is now called only after the
> common flow is guaranteed to succeed.  Arch code can still fail, but
> it's responsible for its own cleanup in that case.
> 
> Eliminating the error path's abuse of kvm_free_memslot() paves the way
> for simplifying kvm_free_memslot(), i.e. dropping its @dont param.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  virt/kvm/kvm_main.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index d403e93e3028..6b2261a9e139 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1096,7 +1096,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
>  
>  	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
>  	if (!slots)
> -		goto out_free;
> +		goto out_bitmap;
>  	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
>  
>  	if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
> @@ -1144,8 +1144,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
>  	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
>  		slots = install_new_memslots(kvm, as_id, slots);
>  	kvfree(slots);
> -out_free:
> -	kvm_free_memslot(kvm, &new, &old);
> +out_bitmap:
> +	if (new.dirty_bitmap && !old.dirty_bitmap)
> +		kvm_destroy_dirty_bitmap(&new);

What if both the old and new have KVM_MEM_LOG_DIRTY_PAGES set?
kvm_free_memslot() did cover that but I see that you explicitly
dropped it.  Could I ask why?  Thanks,

-- 
Peter Xu


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot
  2019-12-17 22:20     ` Sean Christopherson
@ 2019-12-17 22:37       ` Peter Xu
  0 siblings, 0 replies; 37+ messages in thread
From: Peter Xu @ 2019-12-17 22:37 UTC (permalink / raw)
  To: Sean Christopherson
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson,
	David Gibson

On Tue, Dec 17, 2019 at 02:20:59PM -0800, Sean Christopherson wrote:
> > For example, I see PPC has this:
> > 
> > struct kvm_arch_memory_slot {
> > #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE
> > 	unsigned long *rmap;
> > #endif /* CONFIG_KVM_BOOK3S_HV_POSSIBLE */
> > };
> > 
> > I started to look into HV code of it a bit, then I see...
> > 
> >  - kvm_arch_create_memslot(kvmppc_core_create_memslot_hv) init slot->arch.rmap,
> >  - kvm_arch_flush_shadow_memslot(kvmppc_core_flush_memslot_hv) didn't free it,
> >  - kvm_arch_prepare_memory_region(kvmppc_core_prepare_memory_region_hv) is nop.
> > 
> > So Does it have similar issue?
> 
> No, KVM doesn't allow a memslot's size to be changed, and PPC's rmap
> allocation is directly tied to the size of the memslot.  The x86 bug exists
> because the size of its metadata arrays varies based on the alignment of
> the base gfn.

Yes, I was actually thinking those rmap would be invalid rather than
the size after the move.  But I think kvm_arch_flush_shadow_memslot()
will flush all of them anyways... So yes it seems fine.

Thanks,

-- 
Peter Xu


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 11/19] KVM: x86: Free arrays for old memslot when moving memslot's base gfn
  2019-12-17 20:40 ` [PATCH v4 11/19] KVM: x86: Free arrays for old memslot when moving memslot's base gfn Sean Christopherson
@ 2019-12-17 22:48   ` Peter Xu
  0 siblings, 0 replies; 37+ messages in thread
From: Peter Xu @ 2019-12-17 22:48 UTC (permalink / raw)
  To: Sean Christopherson
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson

On Tue, Dec 17, 2019 at 12:40:33PM -0800, Sean Christopherson wrote:
> Explicitly free the metadata arrays (stored in slot->arch) in the old
> memslot structure when moving the memslot's base gfn is committed.  This
> eliminates x86's dependency on kvm_free_memslot() being called when a
> memlsot move is committed, and paves the way for removing the funky code
> in kvm_free_memslot() that conditionally frees structures based on its
> @dont param.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap
  2019-12-17 22:24   ` Peter Xu
@ 2019-12-17 22:51     ` Sean Christopherson
  2019-12-18 16:17       ` Peter Xu
  0 siblings, 1 reply; 37+ messages in thread
From: Sean Christopherson @ 2019-12-17 22:51 UTC (permalink / raw)
  To: Peter Xu
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson

On Tue, Dec 17, 2019 at 05:24:46PM -0500, Peter Xu wrote:
> On Tue, Dec 17, 2019 at 12:40:29PM -0800, Sean Christopherson wrote:
> > Explicitly free an allocated-but-unused dirty bitmap instead of relying
> > on kvm_free_memslot() if an error occurs in __kvm_set_memory_region().
> > There is no longer a need to abuse kvm_free_memslot() to free arch
> > specific resources as arch specific code is now called only after the
> > common flow is guaranteed to succeed.  Arch code can still fail, but
> > it's responsible for its own cleanup in that case.
> > 
> > Eliminating the error path's abuse of kvm_free_memslot() paves the way
> > for simplifying kvm_free_memslot(), i.e. dropping its @dont param.
> > 
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > ---
> >  virt/kvm/kvm_main.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index d403e93e3028..6b2261a9e139 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -1096,7 +1096,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> >  
> >  	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
> >  	if (!slots)
> > -		goto out_free;
> > +		goto out_bitmap;
> >  	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
> >  
> >  	if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
> > @@ -1144,8 +1144,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
> >  	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
> >  		slots = install_new_memslots(kvm, as_id, slots);
> >  	kvfree(slots);
> > -out_free:
> > -	kvm_free_memslot(kvm, &new, &old);
> > +out_bitmap:
> > +	if (new.dirty_bitmap && !old.dirty_bitmap)
> > +		kvm_destroy_dirty_bitmap(&new);
> 
> What if both the old and new have KVM_MEM_LOG_DIRTY_PAGES set?
> kvm_free_memslot() did cover that but I see that you explicitly
> dropped it.  Could I ask why?  Thanks,

In that case, old.dirty_bitmap == new.dirty_bitmap, i.e. shouldn't be freed
by this error path since doing so would result in a use-after-free via the
old memslot.

The kvm_free_memslot() logic is the same, albeit in a very twisted way.

In __kvm_set_memory_region(), @old and @new start with the same dirty_bitmap.

	new = old = *slot;

And @new is modified based on KVM_MEM_LOG_DIRTY_PAGES.  If LOG_DIRTY_PAGES
is set in both @new and @old, then both the "if" and "else if" evaluate
false, i.e. new.dirty_bitmap == old.dirty_bitmap.

	/* Allocate/free page dirty bitmap as needed */
	if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
		new.dirty_bitmap = NULL;
	else if (!new.dirty_bitmap) {
		r = kvm_create_dirty_bitmap(&new);
		if (r)
			return r;
	}

Subbing "@free <= @new" and "@dont <= @old" in kvm_free_memslot()

  static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
			       struct kvm_memory_slot *dont)
  {
	if (!dont || free->dirty_bitmap != dont->dirty_bitmap)
		kvm_destroy_dirty_bitmap(free);


yeids this, since @old is obviously non-NULL

	if (new.dirty_bitmap != old.dirty_bitmap)
		kvm_destroy_dirty_bitmap(&new);

The dirty_bitmap allocation logic guarantees that new.dirty_bitmap is
  a) NULL (the "if" case")
  b) != old.dirty_bitmap iff old.dirty_bitmap == NULL (the "else if" case)
  c) == old.dirty_bitmap (the implicit "else" case).

kvm_free_memslot() frees @new.dirty_bitmap iff its != @old.dirty_bitmap,
thus the explicit destroy only needs to check for (b).

^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION
  2019-12-17 20:40 ` [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION Sean Christopherson
@ 2019-12-18 11:29   ` Christian Borntraeger
  2019-12-18 11:39   ` Christian Borntraeger
  1 sibling, 0 replies; 37+ messages in thread
From: Christian Borntraeger @ 2019-12-18 11:29 UTC (permalink / raw)
  To: Sean Christopherson, James Hogan, Paul Mackerras, Janosch Frank,
	Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Vitaly Kuznetsov, Wanpeng Li,
	Jim Mattson, Joerg Roedel, James Morse, Julien Thierry,
	Suzuki K Poulose, linux-mips, kvm-ppc, kvm, linux-arm-kernel,
	kvmarm, linux-kernel, Christoffer Dall,
	Philippe Mathieu-Daudé



On 17.12.19 21:40, Sean Christopherson wrote:
> Add a KVM selftest to test moving the base gfn of a userspace memory
> region.  The test is primarily targeted at x86 to verify its memslot
> metadata is correctly updated, but also provides basic functionality
> coverage on other architectures.

This fails to build on s390 (and probably others)

set_memory_region_test.c: In function ‘test_move_memory_region’:
set_memory_region_test.c:78:2: warning: implicit declaration of function ‘vcpu_set_cpuid’ [-Wimplicit-function-declaration]
   78 |  vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
      |  ^~~~~~~~~~~~~~
set_memory_region_test.c:78:30: warning: implicit declaration of function ‘kvm_get_supported_cpuid’ [-Wimplicit-function-declaration]
   78 |  vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
      |                              ^~~~~~~~~~~~~~~~~~~~~~~


> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  tools/testing/selftests/kvm/.gitignore        |   1 +
>  tools/testing/selftests/kvm/Makefile          |   3 +
>  .../testing/selftests/kvm/include/kvm_util.h  |   1 +
>  tools/testing/selftests/kvm/lib/kvm_util.c    |  30 ++++
>  .../selftests/kvm/set_memory_region_test.c    | 142 ++++++++++++++++++
>  5 files changed, 177 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/set_memory_region_test.c
> 
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 30072c3f52fb..6f60ceb81440 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -17,3 +17,4 @@
>  /clear_dirty_log_test
>  /dirty_log_test
>  /kvm_create_max_vcpus
> +/set_memory_region_test
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 3138a916574a..01c79e02c5b7 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -29,15 +29,18 @@ TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
>  TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
>  TEST_GEN_PROGS_x86_64 += dirty_log_test
>  TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
> +TEST_GEN_PROGS_x86_64 += set_memory_region_test
>  
>  TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
>  TEST_GEN_PROGS_aarch64 += dirty_log_test
>  TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
> +TEST_GEN_PROGS_aarch64 += set_memory_region_test
>  
>  TEST_GEN_PROGS_s390x = s390x/memop
>  TEST_GEN_PROGS_s390x += s390x/sync_regs_test
>  TEST_GEN_PROGS_s390x += dirty_log_test
>  TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
> +TEST_GEN_PROGS_s390x += set_memory_region_test
>  
>  TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
>  LIBKVM += $(LIBKVM_$(UNAME_M))
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 29cccaf96baf..15d3b8690ffb 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -100,6 +100,7 @@ int _vcpu_ioctl(struct kvm_vm *vm, uint32_t vcpuid, unsigned long ioctl,
>  		void *arg);
>  void vm_ioctl(struct kvm_vm *vm, unsigned long ioctl, void *arg);
>  void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags);
> +void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
>  void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid);
>  vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
>  			  uint32_t data_memslot, uint32_t pgd_memslot);
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 41cf45416060..464a75ce9843 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -756,6 +756,36 @@ void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags)
>  		ret, errno, slot, flags);
>  }
>  
> +/*
> + * VM Memory Region Move
> + *
> + * Input Args:
> + *   vm - Virtual Machine
> + *   slot - Slot of the memory region to move
> + *   flags - Starting guest physical address
> + *
> + * Output Args: None
> + *
> + * Return: None
> + *
> + * Change the gpa of a memory region.
> + */
> +void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa)
> +{
> +	struct userspace_mem_region *region;
> +	int ret;
> +
> +	region = memslot2region(vm, slot);
> +
> +	region->region.guest_phys_addr = new_gpa;
> +
> +	ret = ioctl(vm->fd, KVM_SET_USER_MEMORY_REGION, &region->region);
> +
> +	TEST_ASSERT(!ret, "KVM_SET_USER_MEMORY_REGION failed\n"
> +		    "ret: %i errno: %i slot: %u flags: 0x%x",
> +		    ret, errno, slot, new_gpa);
> +}
> +
>  /*
>   * VCPU mmap Size
>   *
> diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
> new file mode 100644
> index 000000000000..c9603b95ccf7
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/set_memory_region_test.c
> @@ -0,0 +1,142 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define _GNU_SOURCE /* for program_invocation_short_name */
> +#include <fcntl.h>
> +#include <pthread.h>
> +#include <sched.h>
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/ioctl.h>
> +
> +#include <linux/compiler.h>
> +
> +#include <test_util.h>
> +#include <kvm_util.h>
> +#include <processor.h>
> +
> +#define VCPU_ID 0
> +
> +/*
> + * Somewhat arbitrary location and slot, intended to not overlap anything.  The
> + * location and size are specifically 2mb sized/aligned so that the initial
> + * region corresponds to exactly one large page (on x86 and arm64).
> + */
> +#define MEM_REGION_GPA		0xc0000000
> +#define MEM_REGION_SIZE		0x200000
> +#define MEM_REGION_SLOT		10
> +
> +static void guest_code(void)
> +{
> +	uint64_t val;
> +
> +	do {
> +		val = READ_ONCE(*((uint64_t *)MEM_REGION_GPA));
> +	} while (!val);
> +
> +	if (val != 1)
> +		ucall(UCALL_ABORT, 1, val);
> +
> +	GUEST_DONE();
> +}
> +
> +static void *vcpu_worker(void *data)
> +{
> +	struct kvm_vm *vm = data;
> +	struct kvm_run *run;
> +	struct ucall uc;
> +	uint64_t cmd;
> +
> +	/*
> +	 * Loop until the guest is done.  Re-enter the guest on all MMIO exits,
> +	 * which will occur if the guest attempts to access a memslot while it
> +	 * is being moved.
> +	 */
> +	run = vcpu_state(vm, VCPU_ID);
> +	do {
> +		vcpu_run(vm, VCPU_ID);
> +	} while (run->exit_reason == KVM_EXIT_MMIO);
> +
> +	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
> +		    "Unexpected exit reason = %d", run->exit_reason);
> +
> +	cmd = get_ucall(vm, VCPU_ID, &uc);
> +	TEST_ASSERT(cmd == UCALL_DONE, "Unexpected val in guest = %llu",
> +		    uc.args[0]);
> +	return NULL;
> +}
> +
> +static void test_move_memory_region(void)
> +{
> +	pthread_t vcpu_thread;
> +	struct kvm_vm *vm;
> +	uint64_t *hva;
> +	uint64_t gpa;
> +
> +	vm = vm_create_default(VCPU_ID, 0, guest_code);
> +
> +	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
> +
> +	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_THP,
> +				    MEM_REGION_GPA, MEM_REGION_SLOT,
> +				    MEM_REGION_SIZE / getpagesize(), 0);
> +
> +	/*
> +	 * Allocate and map two pages so that the GPA accessed by guest_code()
> +	 * stays valid across the memslot move.
> +	 */
> +	gpa = vm_phy_pages_alloc(vm, 2, MEM_REGION_GPA, MEM_REGION_SLOT);
> +	TEST_ASSERT(gpa == MEM_REGION_GPA, "Failed vm_phy_pages_alloc\n");
> +
> +	virt_map(vm, MEM_REGION_GPA, MEM_REGION_GPA, 2 * 4096, 0);
> +
> +	/* Ditto for the host mapping so that both pages can be zeroed. */
> +	hva = addr_gpa2hva(vm, MEM_REGION_GPA);
> +	memset(hva, 0, 2 * 4096);
> +
> +	pthread_create(&vcpu_thread, NULL, vcpu_worker, vm);
> +
> +	/* Ensure the guest thread is spun up. */
> +	usleep(100000);
> +
> +	/*
> +	 * Shift the region's base GPA.  The guest should not see "2" as the
> +	 * hva->gpa translation is misaligned, i.e. the guest is accessing a
> +	 * different host pfn.
> +	 */
> +	vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA - 4096);
> +	WRITE_ONCE(*hva, 2);
> +
> +	usleep(100000);
> +
> +	/*
> +	 * Note, value in memory needs to be changed *before* restoring the
> +	 * memslot, else the guest could race the update and see "2".
> +	 */
> +	WRITE_ONCE(*hva, 1);
> +
> +	/* Restore the original base, the guest should see "1". */
> +	vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA);
> +
> +	pthread_join(vcpu_thread, NULL);
> +
> +	kvm_vm_free(vm);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	int i, loops;
> +
> +	/* Tell stdout not to buffer its content */
> +	setbuf(stdout, NULL);
> +
> +	if (argc > 1)
> +		loops = atoi(argv[1]);
> +	else
> +		loops = 10;
> +
> +	for (i = 0; i < loops; i++)
> +		test_move_memory_region();
> +
> +	return 0;
> +}
> 


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION
  2019-12-17 20:40 ` [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION Sean Christopherson
  2019-12-18 11:29   ` Christian Borntraeger
@ 2019-12-18 11:39   ` Christian Borntraeger
  2019-12-18 16:39     ` Sean Christopherson
  1 sibling, 1 reply; 37+ messages in thread
From: Christian Borntraeger @ 2019-12-18 11:39 UTC (permalink / raw)
  To: Sean Christopherson, James Hogan, Paul Mackerras, Janosch Frank,
	Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Vitaly Kuznetsov, Wanpeng Li,
	Jim Mattson, Joerg Roedel, James Morse, Julien Thierry,
	Suzuki K Poulose, linux-mips, kvm-ppc, kvm, linux-arm-kernel,
	kvmarm, linux-kernel, Christoffer Dall,
	Philippe Mathieu-Daudé



On 17.12.19 21:40, Sean Christopherson wrote:
> Add a KVM selftest to test moving the base gfn of a userspace memory
> region.  The test is primarily targeted at x86 to verify its memslot
> metadata is correctly updated, but also provides basic functionality
> coverage on other architectures.
> 
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  tools/testing/selftests/kvm/.gitignore        |   1 +
>  tools/testing/selftests/kvm/Makefile          |   3 +
>  .../testing/selftests/kvm/include/kvm_util.h  |   1 +
>  tools/testing/selftests/kvm/lib/kvm_util.c    |  30 ++++
>  .../selftests/kvm/set_memory_region_test.c    | 142 ++++++++++++++++++
>  5 files changed, 177 insertions(+)
>  create mode 100644 tools/testing/selftests/kvm/set_memory_region_test.c
> 
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 30072c3f52fb..6f60ceb81440 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -17,3 +17,4 @@
>  /clear_dirty_log_test
>  /dirty_log_test
>  /kvm_create_max_vcpus
> +/set_memory_region_test
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 3138a916574a..01c79e02c5b7 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -29,15 +29,18 @@ TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
>  TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
>  TEST_GEN_PROGS_x86_64 += dirty_log_test
>  TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
> +TEST_GEN_PROGS_x86_64 += set_memory_region_test
> 
>  TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
>  TEST_GEN_PROGS_aarch64 += dirty_log_test
>  TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
> +TEST_GEN_PROGS_aarch64 += set_memory_region_test
> 
>  TEST_GEN_PROGS_s390x = s390x/memop
>  TEST_GEN_PROGS_s390x += s390x/sync_regs_test
>  TEST_GEN_PROGS_s390x += dirty_log_test
>  TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
> +TEST_GEN_PROGS_s390x += set_memory_region_test
> 
>  TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
>  LIBKVM += $(LIBKVM_$(UNAME_M))
> diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
> index 29cccaf96baf..15d3b8690ffb 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util.h
> @@ -100,6 +100,7 @@ int _vcpu_ioctl(struct kvm_vm *vm, uint32_t vcpuid, unsigned long ioctl,
>  		void *arg);
>  void vm_ioctl(struct kvm_vm *vm, unsigned long ioctl, void *arg);
>  void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags);
> +void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
>  void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid);
>  vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
>  			  uint32_t data_memslot, uint32_t pgd_memslot);
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 41cf45416060..464a75ce9843 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -756,6 +756,36 @@ void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags)
>  		ret, errno, slot, flags);
>  }
> 
> +/*
> + * VM Memory Region Move
> + *
> + * Input Args:
> + *   vm - Virtual Machine
> + *   slot - Slot of the memory region to move
> + *   flags - Starting guest physical address
> + *
> + * Output Args: None
> + *
> + * Return: None
> + *
> + * Change the gpa of a memory region.
> + */
> +void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa)
> +{
> +	struct userspace_mem_region *region;
> +	int ret;
> +
> +	region = memslot2region(vm, slot);
> +
> +	region->region.guest_phys_addr = new_gpa;
> +
> +	ret = ioctl(vm->fd, KVM_SET_USER_MEMORY_REGION, &region->region);
> +
> +	TEST_ASSERT(!ret, "KVM_SET_USER_MEMORY_REGION failed\n"
> +		    "ret: %i errno: %i slot: %u flags: 0x%x",
> +		    ret, errno, slot, new_gpa);
> +}
> +
>  /*
>   * VCPU mmap Size
>   *
> diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
> new file mode 100644
> index 000000000000..c9603b95ccf7
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/set_memory_region_test.c
> @@ -0,0 +1,142 @@
> +// SPDX-License-Identifier: GPL-2.0
> +#define _GNU_SOURCE /* for program_invocation_short_name */
> +#include <fcntl.h>
> +#include <pthread.h>
> +#include <sched.h>
> +#include <signal.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/ioctl.h>
> +
> +#include <linux/compiler.h>
> +
> +#include <test_util.h>
> +#include <kvm_util.h>
> +#include <processor.h>
> +
> +#define VCPU_ID 0
> +
> +/*
> + * Somewhat arbitrary location and slot, intended to not overlap anything.  The
> + * location and size are specifically 2mb sized/aligned so that the initial
> + * region corresponds to exactly one large page (on x86 and arm64).
> + */
> +#define MEM_REGION_GPA		0xc0000000
> +#define MEM_REGION_SIZE		0x200000
> +#define MEM_REGION_SLOT		10
> +
> +static void guest_code(void)
> +{
> +	uint64_t val;
> +
> +	do {
> +		val = READ_ONCE(*((uint64_t *)MEM_REGION_GPA));
> +	} while (!val);
> +
> +	if (val != 1)
> +		ucall(UCALL_ABORT, 1, val);
> +
> +	GUEST_DONE();
> +}
> +
> +static void *vcpu_worker(void *data)
> +{
> +	struct kvm_vm *vm = data;
> +	struct kvm_run *run;
> +	struct ucall uc;
> +	uint64_t cmd;
> +
> +	/*
> +	 * Loop until the guest is done.  Re-enter the guest on all MMIO exits,
> +	 * which will occur if the guest attempts to access a memslot while it
> +	 * is being moved.
> +	 */
> +	run = vcpu_state(vm, VCPU_ID);
> +	do {
> +		vcpu_run(vm, VCPU_ID);
> +	} while (run->exit_reason == KVM_EXIT_MMIO);
> +
> +	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
> +		    "Unexpected exit reason = %d", run->exit_reason);


This will also not work for s390. Maybe just make this test x86 specific for now?


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 00/19] KVM: Dynamically size memslot arrays
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (18 preceding siblings ...)
  2019-12-17 20:40 ` [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION Sean Christopherson
@ 2019-12-18 11:40 ` Christian Borntraeger
  2019-12-18 18:10 ` Marc Zyngier
  20 siblings, 0 replies; 37+ messages in thread
From: Christian Borntraeger @ 2019-12-18 11:40 UTC (permalink / raw)
  To: Sean Christopherson, James Hogan, Paul Mackerras, Janosch Frank,
	Paolo Bonzini, Marc Zyngier
  Cc: David Hildenbrand, Cornelia Huck, Vitaly Kuznetsov, Wanpeng Li,
	Jim Mattson, Joerg Roedel, James Morse, Julien Thierry,
	Suzuki K Poulose, linux-mips, kvm-ppc, kvm, linux-arm-kernel,
	kvmarm, linux-kernel, Christoffer Dall,
	Philippe Mathieu-Daudé



On 17.12.19 21:40, Sean Christopherson wrote:
> The end goal of this series is to dynamically size the memslot array so
> that KVM allocates memory based on the number of memslots in use, as
> opposed to unconditionally allocating memory for the maximum number of
> memslots.  On x86, each memslot consumes 88 bytes, and so with 2 address
> spaces of 512 memslots, each VM consumes ~90k bytes for the memslots.
> E.g. given a VM that uses a total of 30 memslots, dynamic sizing reduces
> the memory footprint from 90k to ~2.6k bytes.
> 
> The changes required to support dynamic sizing are relatively small,
> e.g. are essentially contained in patches 17/19 and 18/19.
> 
> Patches 2-16 clean up the memslot code, which has gotten quite crusty,
> especially __kvm_set_memory_region().  The clean up is likely not strictly
> necessary to switch to dynamic sizing, but I didn't have a remotely
> reasonable level of confidence in the correctness of the dynamic sizing
> without first doing the clean up.
> 
> The only functional change in v4 is the addition of an x86-specific bug
> fix in x86's handling of KVM_MR_MOVE.  The bug fix is not directly related
> to dynamically allocating memslots, but it has subtle and hidden conflicts
> with the cleanup patches, and the fix is higher priority than anything
> else in the series, i.e. should be merged first.
> 
> On non-x86 architectures, v3 and v4 should be functionally equivalent,
> the only non-x86 change in v4 is the dropping of a "const" in
> kvm_arch_commit_memory_region().

I gave this series a quick spin and it still seems to work on s390 (minus the selftest).


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap
  2019-12-17 22:51     ` Sean Christopherson
@ 2019-12-18 16:17       ` Peter Xu
  0 siblings, 0 replies; 37+ messages in thread
From: Peter Xu @ 2019-12-18 16:17 UTC (permalink / raw)
  To: Sean Christopherson
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson

On Tue, Dec 17, 2019 at 02:51:18PM -0800, Sean Christopherson wrote:
> On Tue, Dec 17, 2019 at 05:24:46PM -0500, Peter Xu wrote:
> > On Tue, Dec 17, 2019 at 12:40:29PM -0800, Sean Christopherson wrote:
> > > Explicitly free an allocated-but-unused dirty bitmap instead of relying
> > > on kvm_free_memslot() if an error occurs in __kvm_set_memory_region().
> > > There is no longer a need to abuse kvm_free_memslot() to free arch
> > > specific resources as arch specific code is now called only after the
> > > common flow is guaranteed to succeed.  Arch code can still fail, but
> > > it's responsible for its own cleanup in that case.
> > > 
> > > Eliminating the error path's abuse of kvm_free_memslot() paves the way
> > > for simplifying kvm_free_memslot(), i.e. dropping its @dont param.
> > > 
> > > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > > ---
> > >  virt/kvm/kvm_main.c | 7 ++++---
> > >  1 file changed, 4 insertions(+), 3 deletions(-)
> > > 
> > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > > index d403e93e3028..6b2261a9e139 100644
> > > --- a/virt/kvm/kvm_main.c
> > > +++ b/virt/kvm/kvm_main.c
> > > @@ -1096,7 +1096,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
> > >  
> > >  	slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
> > >  	if (!slots)
> > > -		goto out_free;
> > > +		goto out_bitmap;
> > >  	memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));
> > >  
> > >  	if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
> > > @@ -1144,8 +1144,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
> > >  	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
> > >  		slots = install_new_memslots(kvm, as_id, slots);
> > >  	kvfree(slots);
> > > -out_free:
> > > -	kvm_free_memslot(kvm, &new, &old);
> > > +out_bitmap:
> > > +	if (new.dirty_bitmap && !old.dirty_bitmap)
> > > +		kvm_destroy_dirty_bitmap(&new);
> > 
> > What if both the old and new have KVM_MEM_LOG_DIRTY_PAGES set?
> > kvm_free_memslot() did cover that but I see that you explicitly
> > dropped it.  Could I ask why?  Thanks,
> 
> In that case, old.dirty_bitmap == new.dirty_bitmap, i.e. shouldn't be freed
> by this error path since doing so would result in a use-after-free via the
> old memslot.
> 
> The kvm_free_memslot() logic is the same, albeit in a very twisted way.

Yes it is. :)

> 
> In __kvm_set_memory_region(), @old and @new start with the same dirty_bitmap.
> 
> 	new = old = *slot;
> 
> And @new is modified based on KVM_MEM_LOG_DIRTY_PAGES.  If LOG_DIRTY_PAGES
> is set in both @new and @old, then both the "if" and "else if" evaluate
> false, i.e. new.dirty_bitmap == old.dirty_bitmap.
> 
> 	/* Allocate/free page dirty bitmap as needed */
> 	if (!(new.flags & KVM_MEM_LOG_DIRTY_PAGES))
> 		new.dirty_bitmap = NULL;
> 	else if (!new.dirty_bitmap) {
> 		r = kvm_create_dirty_bitmap(&new);
> 		if (r)
> 			return r;
> 	}
> 
> Subbing "@free <= @new" and "@dont <= @old" in kvm_free_memslot()
> 
>   static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *free,
> 			       struct kvm_memory_slot *dont)
>   {
> 	if (!dont || free->dirty_bitmap != dont->dirty_bitmap)
> 		kvm_destroy_dirty_bitmap(free);
> 
> 
> yeids this, since @old is obviously non-NULL
> 
> 	if (new.dirty_bitmap != old.dirty_bitmap)
> 		kvm_destroy_dirty_bitmap(&new);
> 
> The dirty_bitmap allocation logic guarantees that new.dirty_bitmap is
>   a) NULL (the "if" case")
>   b) != old.dirty_bitmap iff old.dirty_bitmap == NULL (the "else if" case)
>   c) == old.dirty_bitmap (the implicit "else" case).
> 
> kvm_free_memslot() frees @new.dirty_bitmap iff its != @old.dirty_bitmap,
> thus the explicit destroy only needs to check for (b).

Thanks for explaining with such a detail.

Reviewed-by: Peter Xu <peterx@redhat.com>

-- 
Peter Xu


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION
  2019-12-18 11:39   ` Christian Borntraeger
@ 2019-12-18 16:39     ` Sean Christopherson
  0 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2019-12-18 16:39 UTC (permalink / raw)
  To: Christian Borntraeger
  Cc: James Hogan, Paul Mackerras, Janosch Frank, Paolo Bonzini,
	Marc Zyngier, David Hildenbrand, Cornelia Huck, Vitaly Kuznetsov,
	Wanpeng Li, Jim Mattson, Joerg Roedel, James Morse,
	Julien Thierry, Suzuki K Poulose, linux-mips, kvm-ppc, kvm,
	linux-arm-kernel, kvmarm, linux-kernel, Christoffer Dall,
	Philippe Mathieu-Daudé

On Wed, Dec 18, 2019 at 12:39:43PM +0100, Christian Borntraeger wrote:
> 
> On 17.12.19 21:40, Sean Christopherson wrote:
> > Add a KVM selftest to test moving the base gfn of a userspace memory
> > region.  The test is primarily targeted at x86 to verify its memslot
> > metadata is correctly updated, but also provides basic functionality
> > coverage on other architectures.
> > +static void *vcpu_worker(void *data)
> > +{
> > +	struct kvm_vm *vm = data;
> > +	struct kvm_run *run;
> > +	struct ucall uc;
> > +	uint64_t cmd;
> > +
> > +	/*
> > +	 * Loop until the guest is done.  Re-enter the guest on all MMIO exits,
> > +	 * which will occur if the guest attempts to access a memslot while it
> > +	 * is being moved.
> > +	 */
> > +	run = vcpu_state(vm, VCPU_ID);
> > +	do {
> > +		vcpu_run(vm, VCPU_ID);
> > +	} while (run->exit_reason == KVM_EXIT_MMIO);
> > +
> > +	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
> > +		    "Unexpected exit reason = %d", run->exit_reason);
> 
> 
> This will also not work for s390. Maybe just make this test x86 specific for now?

Doh, that's obvious in hindsight.  I think the basic premise is also
broken on arm64 as it returns -EFAULT on is_error_noslot_pfn(pfn).  So
yeah, x86 only for now :-(

^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 00/19] KVM: Dynamically size memslot arrays
  2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
                   ` (19 preceding siblings ...)
  2019-12-18 11:40 ` [PATCH v4 00/19] KVM: Dynamically size memslot arrays Christian Borntraeger
@ 2019-12-18 18:10 ` Marc Zyngier
  20 siblings, 0 replies; 37+ messages in thread
From: Marc Zyngier @ 2019-12-18 18:10 UTC (permalink / raw)
  To: Sean Christopherson
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, David Hildenbrand, Cornelia Huck,
	Vitaly Kuznetsov, Wanpeng Li, Jim Mattson, Joerg Roedel,
	James Morse, Julien Thierry, Suzuki K Poulose, linux-mips,
	kvm-ppc, kvm, linux-arm-kernel, kvmarm, linux-kernel,
	Christoffer Dall, Philippe Mathieu-Daudé

On 2019-12-17 20:40, Sean Christopherson wrote:
> The end goal of this series is to dynamically size the memslot array 
> so
> that KVM allocates memory based on the number of memslots in use, as
> opposed to unconditionally allocating memory for the maximum number 
> of
> memslots.  On x86, each memslot consumes 88 bytes, and so with 2 
> address
> spaces of 512 memslots, each VM consumes ~90k bytes for the memslots.
> E.g. given a VM that uses a total of 30 memslots, dynamic sizing 
> reduces
> the memory footprint from 90k to ~2.6k bytes.
>
> The changes required to support dynamic sizing are relatively small,
> e.g. are essentially contained in patches 17/19 and 18/19.
>
> Patches 2-16 clean up the memslot code, which has gotten quite 
> crusty,
> especially __kvm_set_memory_region().  The clean up is likely not 
> strictly
> necessary to switch to dynamic sizing, but I didn't have a remotely
> reasonable level of confidence in the correctness of the dynamic 
> sizing
> without first doing the clean up.
>
> The only functional change in v4 is the addition of an x86-specific 
> bug
> fix in x86's handling of KVM_MR_MOVE.  The bug fix is not directly 
> related
> to dynamically allocating memslots, but it has subtle and hidden 
> conflicts
> with the cleanup patches, and the fix is higher priority than 
> anything
> else in the series, i.e. should be merged first.
>
> On non-x86 architectures, v3 and v4 should be functionally 
> equivalent,
> the only non-x86 change in v4 is the dropping of a "const" in
> kvm_arch_commit_memory_region().

Gave it another go on top of 5.5-rc2 on an arm64 box, and nothing
exploded. So thumbs up from me.

Thanks,

        M.
-- 
Jazz is not dead. It just smells funny...

^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log()
  2019-12-17 20:40 ` [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log() Sean Christopherson
@ 2019-12-24 18:19   ` Peter Xu
  2020-01-14 18:25     ` Sean Christopherson
  0 siblings, 1 reply; 37+ messages in thread
From: Peter Xu @ 2019-12-24 18:19 UTC (permalink / raw)
  To: Sean Christopherson
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson

On Tue, Dec 17, 2019 at 12:40:38PM -0800, Sean Christopherson wrote:
> +int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
> +		      int *is_dirty, struct kvm_memory_slot **memslot)
>  {
>  	struct kvm_memslots *slots;
> -	struct kvm_memory_slot *memslot;
>  	int i, as_id, id;
>  	unsigned long n;
>  	unsigned long any = 0;
>  
> +	*memslot = NULL;
> +	*is_dirty = 0;
> +
>  	as_id = log->slot >> 16;
>  	id = (u16)log->slot;
>  	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
>  		return -EINVAL;
>  
>  	slots = __kvm_memslots(kvm, as_id);
> -	memslot = id_to_memslot(slots, id);
> -	if (!memslot->dirty_bitmap)
> +	*memslot = id_to_memslot(slots, id);
> +	if (!(*memslot)->dirty_bitmap)
>  		return -ENOENT;
>  
> -	n = kvm_dirty_bitmap_bytes(memslot);
> +	kvm_arch_sync_dirty_log(kvm, *memslot);

Should this line belong to previous patch?

> +
> +	n = kvm_dirty_bitmap_bytes(*memslot);
>  
>  	for (i = 0; !any && i < n/sizeof(long); ++i)
> -		any = memslot->dirty_bitmap[i];
> +		any = (*memslot)->dirty_bitmap[i];
>  
> -	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
> +	if (copy_to_user(log->dirty_bitmap, (*memslot)->dirty_bitmap, n))
>  		return -EFAULT;
>  
>  	if (any)
> -- 
> 2.24.1

-- 
Peter Xu


^ permalink raw reply	[flat|nested] 37+ messages in thread

* Re: [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log()
  2019-12-24 18:19   ` Peter Xu
@ 2020-01-14 18:25     ` Sean Christopherson
  0 siblings, 0 replies; 37+ messages in thread
From: Sean Christopherson @ 2020-01-14 18:25 UTC (permalink / raw)
  To: Peter Xu
  Cc: James Hogan, Paul Mackerras, Christian Borntraeger,
	Janosch Frank, Paolo Bonzini, Marc Zyngier, linux-arm-kernel,
	Wanpeng Li, Philippe Mathieu-Daudé,
	kvm, David Hildenbrand, Joerg Roedel, Cornelia Huck, linux-mips,
	linux-kernel, kvm-ppc, Vitaly Kuznetsov, kvmarm, Jim Mattson

On Tue, Dec 24, 2019 at 01:19:30PM -0500, Peter Xu wrote:
> On Tue, Dec 17, 2019 at 12:40:38PM -0800, Sean Christopherson wrote:
> > +int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log,
> > +		      int *is_dirty, struct kvm_memory_slot **memslot)
> >  {
> >  	struct kvm_memslots *slots;
> > -	struct kvm_memory_slot *memslot;
> >  	int i, as_id, id;
> >  	unsigned long n;
> >  	unsigned long any = 0;
> >  
> > +	*memslot = NULL;
> > +	*is_dirty = 0;
> > +
> >  	as_id = log->slot >> 16;
> >  	id = (u16)log->slot;
> >  	if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS)
> >  		return -EINVAL;
> >  
> >  	slots = __kvm_memslots(kvm, as_id);
> > -	memslot = id_to_memslot(slots, id);
> > -	if (!memslot->dirty_bitmap)
> > +	*memslot = id_to_memslot(slots, id);
> > +	if (!(*memslot)->dirty_bitmap)
> >  		return -ENOENT;
> >  
> > -	n = kvm_dirty_bitmap_bytes(memslot);
> > +	kvm_arch_sync_dirty_log(kvm, *memslot);
> 
> Should this line belong to previous patch?

No.

The previous patch, "KVM: Provide common implementation for generic dirty
log functions", is consolidating the implementation of dirty log functions
for architectures with CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT=y.

This code is being moved from s390's kvm_vm_ioctl_get_dirty_log(), as s390
doesn't select KVM_GENERIC_DIRTYLOG_READ_PROTECT.  It's functionally a nop
as kvm_arch_sync_dirty_log() is empty for PowerPC, the only other arch that
doesn't select KVM_GENERIC_DIRTYLOG_READ_PROTECT.

Arguably, the call to kvm_arch_sync_dirty_log() should be moved in a
separate prep patch.  It can't be a follow-on patch as that would swap the
ordering of kvm_arch_sync_dirty_log() and kvm_dirty_bitmap_bytes(), etc...

My reasoning for not splitting it to a separate patch is that prior to this
patch, the common code and arch specific code are doing separate memslot
lookups via id_to_memslot(), i.e. moving the kvm_arch_sync_dirty_log() call
would operate on a "different" memslot.   It can't actually be a different
memslot because slots_lock is held, it just felt weird.

All that being said, I don't have a strong opinion on moving the call to
kvm_arch_sync_dirty_log() in a separate patch; IIRC, I vascillated between
the two options when writing the code.  If anyone wants it to be a separate
patch I'll happily split it out.

> 
> > +
> > +	n = kvm_dirty_bitmap_bytes(*memslot);
> >  
> >  	for (i = 0; !any && i < n/sizeof(long); ++i)
> > -		any = memslot->dirty_bitmap[i];
> > +		any = (*memslot)->dirty_bitmap[i];
> >  
> > -	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
> > +	if (copy_to_user(log->dirty_bitmap, (*memslot)->dirty_bitmap, n))
> >  		return -EFAULT;
> >  
> >  	if (any)
> > -- 
> > 2.24.1
> 
> -- 
> Peter Xu
> 

^ permalink raw reply	[flat|nested] 37+ messages in thread

end of thread, back to index

Thread overview: 37+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-12-17 20:40 [PATCH v4 00/19] KVM: Dynamically size memslot arrays Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 01/19] KVM: x86: Allocate new rmap and large page tracking when moving memslot Sean Christopherson
2019-12-17 20:48   ` Sean Christopherson
2019-12-17 20:50     ` Sean Christopherson
2019-12-17 21:56   ` Peter Xu
2019-12-17 22:20     ` Sean Christopherson
2019-12-17 22:37       ` Peter Xu
2019-12-17 20:40 ` [PATCH v4 02/19] KVM: Reinstall old memslots if arch preparation fails Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 03/19] KVM: Don't free new memslot if allocation of said memslot fails Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 04/19] KVM: PPC: Move memslot memory allocation into prepare_memory_region() Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 05/19] KVM: x86: Allocate memslot resources during prepare_memory_region() Sean Christopherson
2019-12-17 22:07   ` Peter Xu
2019-12-17 20:40 ` [PATCH v4 06/19] KVM: Drop kvm_arch_create_memslot() Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 07/19] KVM: Explicitly free allocated-but-unused dirty bitmap Sean Christopherson
2019-12-17 22:24   ` Peter Xu
2019-12-17 22:51     ` Sean Christopherson
2019-12-18 16:17       ` Peter Xu
2019-12-17 20:40 ` [PATCH v4 08/19] KVM: Refactor error handling for setting memory region Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 09/19] KVM: Move setting of memslot into helper routine Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 10/19] KVM: Drop "const" attribute from old memslot in commit_memory_region() Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 11/19] KVM: x86: Free arrays for old memslot when moving memslot's base gfn Sean Christopherson
2019-12-17 22:48   ` Peter Xu
2019-12-17 20:40 ` [PATCH v4 12/19] KVM: Move memslot deletion to helper function Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 13/19] KVM: Simplify kvm_free_memslot() and all its descendents Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 14/19] KVM: Clean up local variable usage in __kvm_set_memory_region() Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 15/19] KVM: Provide common implementation for generic dirty log functions Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 16/19] KVM: Ensure validity of memslot with respect to kvm_get_dirty_log() Sean Christopherson
2019-12-24 18:19   ` Peter Xu
2020-01-14 18:25     ` Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 17/19] KVM: Terminate memslot walks via used_slots Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 18/19] KVM: Dynamically size memslot array based on number of used slots Sean Christopherson
2019-12-17 20:40 ` [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION Sean Christopherson
2019-12-18 11:29   ` Christian Borntraeger
2019-12-18 11:39   ` Christian Borntraeger
2019-12-18 16:39     ` Sean Christopherson
2019-12-18 11:40 ` [PATCH v4 00/19] KVM: Dynamically size memslot arrays Christian Borntraeger
2019-12-18 18:10 ` Marc Zyngier

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