iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

KVM: x86/mmu: Check for present SPTE when clearing dirty bit in TDP MMU

Browse Source 
commit 3354ef5a592d219364cf442c2f784ce7ad7629fd upstream.

Explicitly check for present SPTEs when clearing dirty bits in the TDP
MMU.  This isn't strictly required for correctness, as setting the dirty
bit in a defunct SPTE will not change the SPTE from !PRESENT to PRESENT.
However, the guarded MMU_WARN_ON() in spte_ad_need_write_protect() would
complain if anyone actually turned on KVM's MMU debugging.

Fixes: a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP MMU")
Cc: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-3-seanjc@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sean Christopherson 2022-02-26 00:15:20 +00:00 committed by Greg Kroah-Hartman
parent a3ad453008
commit 89e5a42687
1 changed files with 3 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/kvm/mmu/tdp_mmu.c
View File

@ -902,6 +902,9 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
if (tdp_mmu_iter_cond_resched(kvm, &iter, false))
continue;
if (!is_shadow_present_pte(iter.old_spte))
continue;
if (spte_ad_need_write_protect(iter.old_spte)) {
if (is_writable_pte(iter.old_spte))
new_spte = iter.old_spte & ~PT_WRITABLE_MASK;