From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792774173; b=lQnErD+gCFsUPLqW8Iu1KxoTkqvX0mlKSLE3Iq1UZPcD5R4B7GXO7WIyLDOepmP1BbDA I1ge+Xy/b/BIAv5B8Z2Nc1/lutCwpKwd53xtnSo7YRZlCcIZKtbecxDYpmO8Q6jTXs6fW N70PpY6oSVWoggSRugymSrfvi/QiGhI71AG/Fm/+4nWz3iMhbHooqs58TK69hGcvuwbbI 02KLrJbgcI9r7+VjUbiNMnUHoeKdDb+L5q3hxKnkdrtJoyNIsE3VfvyfGfI8RpIjXWXjg oS5veFzcfGVqW/GqKHMhpVLY+pc+YbDnUH0xjqWsM9EVW98Nkcennk4LAQ4jjzUDSJQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792774173; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=4tYMeib50uGngD/fKnrDQF3E+2eda2J+N7fVBan9apA=; b=ZgLcvXwwwY6siiF13jiEPYYPFU0kTPqYcWL94a3Reni6QbA/jHIhHNHAmfh6NfwuXV9S 6tnMRSa9phy6lpEoI+JpKYoSmGK9XGp67PTSRxFIvfxrdsVdR6uN2gp1k2dGfeMlLczZW 03s178oz6VFHJyssTtiNOH2eefpXyNIyG3cAKMqCdn1sRdkQgv70MthFoHgHpdaRjtEVC zcgRhKTUKlCkuX1xomD+d1mHVMpejlS+yet+hHH4h3FX+WGBTM7WqxNhP3v+PXNjBgEBb 7r7JA1QOKtPqBiex8hsV+9oqk1m1mVRSoU/TYfOm3TBgO9glhWUU59daxywY7mm/azA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b="2RN88qN/"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0E93E606A31B; Fri, 23 Oct 2026 16:49:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=2RN88qN/ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 051C11F01825; Fri, 23 Oct 2026 16:49:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792774172; bh=4tYMeib50uGngD/fKnrDQF3E+2eda2J+N7fVBan9apA=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=2RN88qN/rl9GCWqW+DhHh+1tVSdwVB589VfQT1RzmVRcDYLZWjnnQMDu+RMPf3vJO T9Zg8A46EirHw5KiTc7fA2RV3csAsHFvWACHc0gb4lOeSckTQun40hIkWkTuYRalQP Ad+M8fp1az17F40FIhqPqJkGuSUlkKlLywocAOww= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hyunwoo Kim , Paolo Bonzini , Sean Christopherson , Sasha Levin Subject: [PATCH 6.18 146/193] KVM: x86/mmu: Preserve nested TDP shadow page tables if they are used as roots Date: Fri, 23 Oct 2026 18:37:03 +0200 Message-ID: <20261023163717.663703579@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261023163714.201276352@linuxfoundation.org> References: <20261023163714.201276352@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Sasha Levin --- 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 205d314a7583c..1fa251ca4dccf 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); -- 2.53.0