diff options
| author | Ben Gardon <bgardon@google.com> | 2021-02-02 10:57:22 -0800 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-02-04 05:27:41 -0500 |
| commit | f1b3b06a058bb5c636ffad0afae138fe30775881 (patch) | |
| tree | bf2ab8b034dbb158a159bccf64f296ff41edad9a | |
| parent | 0f99ee2c7a58fc281c084d3acc0f0013bec7ec5a (diff) | |
| download | powerpc-f1b3b06a058bb5c636ffad0afae138fe30775881.tar.gz | |
KVM: x86/mmu: Clear dirtied pages mask bit before early break
In clear_dirty_pt_masked, the loop is intended to exit early after
processing each of the GFNs with corresponding bits set in mask. This
does not work as intended if another thread has already cleared the
dirty bit or writable bit on the SPTE. In that case, the loop would
proceed to the next iteration early and the bit in mask would not be
cleared. As a result the loop could not exit early and would proceed
uselessly. Move the unsetting of the mask bit before the check for a
no-op SPTE change.
Fixes: a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP
MMU")
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20210202185734.1680553-17-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/mmu/tdp_mmu.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index aeb05f626b556b..a75e92164a8b62 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1007,6 +1007,8 @@ static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root, !(mask & (1UL << (iter.gfn - gfn)))) continue; + mask &= ~(1UL << (iter.gfn - gfn)); + if (wrprot || spte_ad_need_write_protect(iter.old_spte)) { if (is_writable_pte(iter.old_spte)) new_spte = iter.old_spte & ~PT_WRITABLE_MASK; @@ -1020,8 +1022,6 @@ static void clear_dirty_pt_masked(struct kvm *kvm, struct kvm_mmu_page *root, } tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); - - mask &= ~(1UL << (iter.gfn - gfn)); } } |