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=1793210119; b=glGTdxLjb1Q98Sgy4+N8jRQax6rNBspKvDq0K6u/TpsELl/Hl2Kwh6mtep5q+v/F8JWV TP7arBKBbIOAiiDWGvYt/MLwMkvGUjOcz+wBlad0lEcmOdfLMWwXrpxnFKXJKzAQX6BF/ r1FBysYNnMEjOTOoK4FQ3FTciSd75wNIcsg/cg1DWqUJ4L3CxiD6Inqj7Ie6E+uoulF7l RgpzFqs/RO3ngT+n2EaeqKGk0rnjvpDp0Ay4JnLnYFTD43Eou8yXUEG67tA3aLG7eN/vr 4K4VKXAa1MbVhfCwZgmPCKS55s7InJFiXWsD7KS/8tIDYASk56YlKQu+MmwzO3TscTg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793210119; 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=LYDOoEIk4ZeNbFmoUODWbmIUgAGgdF9Hf+DCtI/MVT0=; b=qxlv2ZWNZLKNFGbSU3pJfS3kXzapW8wJdgjzZqweLCHgDQybBzwmkZJ2L5UMy06llnd7 9SDKQ22dO0fFfDfLR+i/svPIiyTe4DlaXpSJ5FiddOPFdk6KmEaQr5q0556uUR+0nEkUR mlZgSUK3EOUfNQoSmLqyF/kTg57/Sl2VAO7AqMqCxCn+r6pQylnvWKrMGwLLlrXAkN5qk Y07dBhF4TQpJ37XfCg3aocCOoOLv0oMlZxO6QF0axrfG48G/98MnwBjpgI0mdfT5wnV0z 00eJORc4mwY885wlbx+TDgx8zt5Sg3A7oY9B72v0ABcWEgyfBpnFGlokEBUWjZ63tjg== 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=LOBwIk5s; 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 6863E606A31C; Wed, 28 Oct 2026 17:55:19 +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=LOBwIk5s Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFDA71F01825; Wed, 28 Oct 2026 17:55:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793210119; bh=LYDOoEIk4ZeNbFmoUODWbmIUgAGgdF9Hf+DCtI/MVT0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LOBwIk5s729PXlq9pikrA0pBC6wlBf1OUQNubfYFZIdQ0aHKFgYojqiSKWJ6KpxI7 hpRjOTCNH/COw+/uIySoY2Yinr3EbLP/8IQEF1+kZ9NSuTUJb5Ci8EYWoBbCqs2Td9 HP6D45Q/uR3QDvK5V0ndcrIIfRLEekjmScNDoLxg= 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 6.6 082/168] KVM: x86/mmu: Preserve nested TDP shadow page tables if they are used as roots Date: Wed, 28 Oct 2026 18:00:18 +0100 Message-ID: <20261028165945.027893664@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165943.089486480@linuxfoundation.org> References: <20261028165943.089486480@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 6.6-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 6.12] 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 b243cb405808a..5bff73562cbd1 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2508,7 +2508,9 @@ 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