diff options
| author | Lai Jiangshan <laijs@linux.alibaba.com> | 2021-09-18 08:56:27 +0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-09-23 10:28:44 -0400 |
| commit | f81602958c115fc7c87b985f71574042a20ff858 (patch) | |
| tree | d907a04c9aa0fe43ecafcdf0a6f008566b3987cc /arch | |
| parent | faf6b755629627f19feafa75b32e81cd7738f12d (diff) | |
KVM: X86: Fix missed remote tlb flush in rmap_write_protect()
When kvm->tlbs_dirty > 0, some rmaps might have been deleted
without flushing tlb remotely after kvm_sync_page(). If @gfn
was writable before and it's rmaps was deleted in kvm_sync_page(),
and if the tlb entry is still in a remote running VCPU, the @gfn
is not safely protected.
To fix the problem, kvm_sync_page() does the remote flush when
needed to avoid the problem.
Fixes: a4ee1ca4a36e ("KVM: MMU: delay flush all tlbs on sync_page path")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210918005636.3675-2-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/mmu/paging_tmpl.h | 23 |
1 files changed, 2 insertions, 21 deletions
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h index 7d03e9b7ccfa..efce0a935e23 100644 --- a/arch/x86/kvm/mmu/paging_tmpl.h +++ b/arch/x86/kvm/mmu/paging_tmpl.h @@ -1047,14 +1047,6 @@ static gpa_t FNAME(gva_to_gpa_nested)(struct kvm_vcpu *vcpu, gpa_t vaddr, * Using the cached information from sp->gfns is safe because: * - The spte has a reference to the struct page, so the pfn for a given gfn * can't change unless all sptes pointing to it are nuked first. - * - * Note: - * We should flush all tlbs if spte is dropped even though guest is - * responsible for it. Since if we don't, kvm_mmu_notifier_invalidate_page - * and kvm_mmu_notifier_invalidate_range_start detect the mapping page isn't - * used by guest then tlbs are not flushed, so guest is allowed to access the - * freed pages. - * And we increase kvm->tlbs_dirty to delay tlbs flush in this case. */ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) { @@ -1107,13 +1099,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) return 0; if (FNAME(prefetch_invalid_gpte)(vcpu, sp, &sp->spt[i], gpte)) { - /* - * Update spte before increasing tlbs_dirty to make - * sure no tlb flush is lost after spte is zapped; see - * the comments in kvm_flush_remote_tlbs(). - */ - smp_wmb(); - vcpu->kvm->tlbs_dirty++; + set_spte_ret |= SET_SPTE_NEED_REMOTE_TLB_FLUSH; continue; } @@ -1128,12 +1114,7 @@ static int FNAME(sync_page)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp) if (gfn != sp->gfns[i]) { drop_spte(vcpu->kvm, &sp->spt[i]); - /* - * The same as above where we are doing - * prefetch_invalid_gpte(). - */ - smp_wmb(); - vcpu->kvm->tlbs_dirty++; + set_spte_ret |= SET_SPTE_NEED_REMOTE_TLB_FLUSH; continue; } |