diff options
| author | Marcelo Tosatti <marcelo@kvack.org> | 2007-12-11 19:12:27 -0500 |
|---|---|---|
| committer | Avi Kivity <avi@qumranet.com> | 2008-01-30 17:53:21 +0200 |
| commit | 7819026eefee53eaaac3fdce1a2f157c7ea943fe (patch) | |
| tree | e5ee690406a8ebe381ce5d712f010a5a0c706c4c /drivers/kvm/mmu.c | |
| parent | 1d075434149c38d457c30d1f11d9c39210b0bb79 (diff) | |
KVM: MMU: Fix SMP shadow instantiation race
There is a race where VCPU0 is shadowing a pagetable entry while VCPU1
is updating it, which results in a stale shadow copy.
Fix that by comparing the contents of the cached guest pte with the
current guest pte after write-protecting the guest pagetable.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
Diffstat (limited to 'drivers/kvm/mmu.c')
| -rw-r--r-- | drivers/kvm/mmu.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c index ba71e8d6676..92ac0d1106b 100644 --- a/drivers/kvm/mmu.c +++ b/drivers/kvm/mmu.c @@ -681,7 +681,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, unsigned level, int metaphysical, unsigned access, - u64 *parent_pte) + u64 *parent_pte, + bool *new_page) { union kvm_mmu_page_role role; unsigned index; @@ -720,6 +721,8 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu, vcpu->mmu.prefetch_page(vcpu, sp); if (!metaphysical) rmap_write_protect(vcpu->kvm, gfn); + if (new_page) + *new_page = 1; return sp; } @@ -993,7 +996,8 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, int write, gfn_t gfn) >> PAGE_SHIFT; new_table = kvm_mmu_get_page(vcpu, pseudo_gfn, v, level - 1, - 1, ACC_ALL, &table[index]); + 1, ACC_ALL, &table[index], + NULL); if (!new_table) { pgprintk("nonpaging_map: ENOMEM\n"); return -ENOMEM; @@ -1059,7 +1063,7 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu) ASSERT(!VALID_PAGE(root)); sp = kvm_mmu_get_page(vcpu, root_gfn, 0, - PT64_ROOT_LEVEL, 0, ACC_ALL, NULL); + PT64_ROOT_LEVEL, 0, ACC_ALL, NULL, NULL); root = __pa(sp->spt); ++sp->root_count; vcpu->mmu.root_hpa = root; @@ -1080,7 +1084,7 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu) root_gfn = 0; sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30, PT32_ROOT_LEVEL, !is_paging(vcpu), - ACC_ALL, NULL); + ACC_ALL, NULL, NULL); root = __pa(sp->spt); ++sp->root_count; vcpu->mmu.pae_root[i] = root | PT_PRESENT_MASK; |