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=1793211858; b=g5Yg9xzsiBDwMsR9LxxZ0EWn8PYaSWx9hIH6/3QOFlcZmNEwt3NakSRCnZeapiwJpchl 7LCdAODnqsRdFr2ydeKNMlndxY3Xks/GVf7p6Za/K01jYZroAFHuHXxHMAIa2wcA4tQDK 59n2PxOFFW0PP7eLERQz3H95VH01X9qJu6wR0m3hU5Pd3QaPYzS4cqHOfU2dPUptt4py1 R6wH8RGWi+rkg8pIKzRYSdt6AtEwfdb8JruLLXs0pxSyLiVw9D61pW2yJWY2BfWUFmojN gNSr+px9snvD/REG4zM8kNYGYxSeozO+2h2gvGZe/ThbO5VnJDldg8CtaSLBinIV38A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793211858; 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=EZNoA8R6eHqXEcITk8Y3iinS6mZ7Q0AFdjzeYgooY+I=; b=Ij5kMPvk7x/9lRx7XLyyCd6/2rBs1eblbNOcmFTO7EOGvxbY78oca8RAMP600XsWPl2q PR1gkWbZ/oIsbgcxYYi5EoZimbipU9lO1nSwSHpK+iYYWClMTdVv/CqnR3UBUEIJhf781 f7T0mPNNYK6Wv7lqO6qaN8XsQedxylSpH94lYEEzREmDFPuZEC6XQGN9ll5SvXJWOqkTz ArUBMdUMftAB6cEWDydlm4q47PZig9RHStkRWQsiSzxITYjZqiteXxaJ0B6kNLRws3951 yZMGWXEH0EJUb7OadK28uoy07OeBlrZlROR1GTJmevXEcT4zxvbYwVggSaCS4CDZJKQ== 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=enQkn5Gz; 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 3A77E606A324; Wed, 28 Oct 2026 18:24:18 +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=enQkn5Gz Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85B751F01825; Wed, 28 Oct 2026 18:24:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793211858; bh=EZNoA8R6eHqXEcITk8Y3iinS6mZ7Q0AFdjzeYgooY+I=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=enQkn5GzhWg/PbnwGdxyqMgv6v8aowvnJpbmqk0dxQA2OrlIinlib4yciNigOlxOA fZXexwuKV3oQQ1xVGug3lenHjbBMRAEAjW0/Px+L0RKgoAFgmJlcK2HD+xfCSneDTI RSpVXEVKpJ8G1dX9Ajne/aJk8gbCYlxv333L8mA4= 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 5.15 526/571] KVM: x86/mmu: Preserve nested TDP shadow page tables if they are used as roots Date: Wed, 28 Oct 2026 18:01:13 +0100 Message-ID: <20261028170020.512080794@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@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 5.15-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 [sean: resolve minor conflict due to lack of lockless aging in 5.15] Signed-off-by: Sean Christopherson Signed-off-by: Sasha Levin --- arch/x86/kvm/mmu/mmu.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 081547246801b..a768cbe23808c 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2336,7 +2336,9 @@ static int mmu_page_zap_pte(struct kvm *kvm, struct kvm_mmu_page *sp, * avoids retaining a large number of stale nested SPs. */ if (tdp_enabled && invalid_list && - child->role.guest_mode && !child->parent_ptes.val) + child->role.guest_mode && + !child->root_count && + !child->parent_ptes.val) return kvm_mmu_prepare_zap_page(kvm, child, invalid_list); } -- 2.53.0