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=1794047321; b=Lv2yr9ZfESHH1ydXsK/eeNzy77Bc0s1OpQvh7zpj1CQuMDeO4VNqyqKoHmqtbVK4a8Lj zkM1dvjL0Dlxduo/DXrhGTMqPdslG7f9zHCAcW8DvZ0oIpKRIrwJ/Kts/UEBOlYvuz0AM Djb9EznG/DSMrn6HoIGEDI2ZXZp0eZlnwKSRsPnNpzDKOiSKkOU8Ywlw5GZzItxIKrVDW pROoteSi0urJmDS/yPivHc70lr6c1FfYj5pcI3lmq/iFd5TiRJIXzoO0eg5QNOu8sxLfl dcC85ra/zlGeV87EOwVUU8+cNkhEWwSFBkmNl4ia97oREDu4aAYSXBrRiz7tXJK3kFg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794047321; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=AiCubS16eynK3H117nThpdlBeXj03I2/d/0BU8Ci/bk=; b=Xy2Vm2rSD3Oj3sxnEOShMTHVzgizisQnnuSJWeigG0CdOXgtRTv6Bib/39rCPhcjQJEU 4E4g+m+Y1s54uS1yqZ333SHRpZJU4++6vKHlzpWz2+1xcTZeTbDjlFs+TfxUMNum26RLl hpTPBNuju4KmYqwGna2Gzg5R4l5QMUIkmXCUlckq0VbxU09I1DKWQ9FiMbU6evUW9NnLm ihTKwAHhUIcrOFDLZrAIR/XRNuUoQkDycaZHjqGS01DDSTMzbSj3fG6iPIXg0ibIhTQWK r1Zi2/NHOyM275j5RkotbSblZ2uhW61ETq9wUHfyuaSlyUPar62xLJ3ZXxCmrid7xaQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Lzw8tJf+; 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 B5A4A606A32C for ; Sat, 7 Nov 2026 10:28:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=Lzw8tJf+ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06E731F0089F; Sat, 7 Nov 2026 10:28:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794047320; bh=AiCubS16eynK3H117nThpdlBeXj03I2/d/0BU8Ci/bk=; h=From:To:Cc:Subject:Date; b=Lzw8tJf+8jpikJhoMOQXJHf3a5ZHVk/ShrFoUt4QhUO9c1r2xR6wD24N6zoSQfAbo Vmpr9qLpMHmVaoM95S5j7QMFr7whRvel3HuFS/nb32IzrKE3uv4r5HITjTkgSRT6y/ otiP9511goxQO6f+MHeOALU+8eVH63EHUebxEImsGkGYOr242ZDTFHwOwsPAL2EYNx V+oBj0PL39ThSHR0iS0OjfPpUu62pnLi3ONCY/9Ol0NUnRAtDhGq7MPTaKyQkSJ+fF UFqHu+f/kec54cxLJYor8TuqqutHtmZt+etcqtWYRdbUfYzi9ZfpelBtHZHJVltuYR Zy4oGiyd8WiGw== From: Sasha Levin To: dwmw@amazon.co.uk, sashiko-bot@kernel.org, paul@xen.org, pbonzini@redhat.com Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] KVM: x86/xen: Enforce 4-byte alignment of vcpu_info registration" failed to apply to 6.6-stable tree Date: Sat, 7 Nov 2026 05:28:38 -0500 Message-ID: <20261107052838-failed-6.6-eacdb76c5f04@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x eacdb76c5f04956035c5d7f7e1973028f30684a2 # git commit -s git send-email --to '' --in-reply-to '20261107052838-failed-6.6-eacdb76c5f04@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From eacdb76c5f04956035c5d7f7e1973028f30684a2 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 31 Aug 2026 22:26:37 +0100 Subject: [PATCH] KVM: x86/xen: Enforce 4-byte alignment of vcpu_info registration Xen's map_guest_area() enforces that vcpu_info is aligned to sizeof(xen_ulong_t). KVM has no such check, allowing a guest to register vcpu_info at an arbitrary byte alignment. Enforce unconditional 4-byte alignment regardless of the current shinfo mode. This is sufficient because subsequent commits ensure that all locked atomic operations on vcpu_info fields use at most 32-bit accesses. Return -ENXIO on failure, matching Xen's map_guest_area() behaviour for unaligned requests. Originally observed in review of an unrelated patch: https://lore.kernel.org/all/20260604193554.1BA311F00893@smtp.kernel.org/ Cc: stable@vger.kernel.org Fixes: 73e69a86347a ("KVM: x86/xen: register vcpu info") Reported-by: sashiko-bot@kernel.org Closes: https://lore.kernel.org/all/20260604193554.1BA311F00893@smtp.kernel.org Assisted-by: Kiro:claude-opus-4.6-1m Signed-off-by: David Woodhouse Reviewed-by: Paul Durrant Link: https://patch.msgid.link/20260831213632.81023-7-dwmw2@infradead.org Signed-off-by: Paolo Bonzini --- arch/x86/kvm/xen.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index d0bdc6e8eb28c..15c508b7b28b7 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -941,6 +941,10 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) break; } + r = -ENXIO; + if (!IS_ALIGNED(data->u.gpa, sizeof(u32))) + break; + r = kvm_gpc_activate(&vcpu->arch.xen.vcpu_info_cache, data->u.gpa, sizeof(struct vcpu_info)); } else { @@ -950,6 +954,10 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) break; } + r = -ENXIO; + if (!IS_ALIGNED(data->u.hva, sizeof(u32))) + break; + r = kvm_gpc_activate_hva(&vcpu->arch.xen.vcpu_info_cache, data->u.hva, sizeof(struct vcpu_info)); } -- 2.53.0