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charset="UTF-8" From: Hyunwoo Kim [ Upstream commit 7a2c70e777a00c32ebafd376a6fe31ebb91c5b20 ] kvm_mmu_zap_oldest_mmu_pages() excludes a shadow page whose root_count is non-zero from top-level reclaim, because such a page cannot be freed. The path in mmu_page_zap_pte() that recursively zaps a parentless nested TDP child has no such check. As a result, a shadow page can be zapped even if the page itself can't be freed; as the comment in kvm_mmu_zap_oldest_mmu_pages() notes, zapping it will just force vCPUs to rebuild the page. As in top-level reclaim, do not recursively prepare zapping of a nested TDP child whose root_count is non-zero. Fixes: 2de4085cccea ("KVM: x86/MMU: Recursively zap nested TDP SPs when zapping last/only parent") Signed-off-by: Hyunwoo Kim Signed-off-by: Paolo Bonzini Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/mmu.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 205d314a7583..1fa251ca4dcc 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2630,6 +2630,7 @@ static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, */ if (tdp_enabled && invalid_list && child->role.guest_mode && + !child->root_count && !atomic_long_read(&child->parent_ptes.val)) return kvm_mmu_prepare_zap_page(kvm, child, invalid_list); base-commit: 2ff600d29ee478d0a8d46ef8a58afb5e038fe692 -- 2.56.0.218.g1ec904b173-goog