Re-check that the given SPTE is still a leaf and present SPTE after a
failed cmpxchg in clear_dirty_gfn_range(). clear_dirty_gfn_range()
intends to only operate on present leaf SPTEs, but that could change
after a failed cmpxchg.
A check for present was added in commit 3354ef5a592d ("KVM: x86/mmu:
Check for present SPTE when clearing dirty bit in TDP MMU") but the
check for leaf is still buried in tdp_root_for_each_leaf_pte() and does
not get rechecked on retry.
Fixes: a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP MMU")
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
arch/x86/kvm/mmu/tdp_mmu.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 6cd4dd631a2f..038983b13574 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1522,12 +1522,13 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,
rcu_read_lock();
- tdp_root_for_each_leaf_pte(iter, root, start, end) {
+ tdp_root_for_each_pte(iter, root, start, end) {
retry:
- if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true))
+ if (!is_shadow_present_pte(iter.old_spte) ||
+ !is_last_spte(iter.old_spte, iter.level))
continue;
- if (!is_shadow_present_pte(iter.old_spte))
+ if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true))
continue;
KVM_MMU_WARN_ON(kvm_ad_enabled() &&
--
2.42.0.820.g83a721a137-goog
