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=1794048072; b=EJRLY8Ph4CuSr+u7BDC7sWZznxaGdRQzjsHxdKeECt0gOPrOG9q2tZX0BaDHftQCpQlt EQUdegfy8miGQYy2VJhzE80as5A8g1bSHlXhiLwyRZE7Qh2pUW9JLl55OyS3vV2VO12Kb /vLW9t3V8H6mWNVsW4Tm7v4H++VrJJ8K7EgeHCMuYikbFUVk4A9bYBqq7hrWy6WOwySkA mtqMj0z+YEyKHIk26Gryep5/H55aaazkDjtIIwpcNKfFviqvTb0v82c4eLRLa8GXOdC1D y08lN7gRW2tHSBqbGPg4Ku32L/ZWWwQRRdCvNdfmbO4ZDA107RaxtBDzmWCObXKwZog== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794048072; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=Nvsa4839TkKWUA7CtpKYp/pQEc9aAk/VAevWqSa2dYc=; b=DKurhrV3w2QYtyFiDzxYKOraLEIHp5Lpl+U3KTT3TrMIeae4Oxy8abx7xTGx+FtN2JZT PB54F8TGIsIcL63byOLIGohSyFImHy9r6si1p58s3vsmFNWroCSW2WMl6aRLbW84+ptUT wvFoXMpx++iFZeNaPTnF36EyYuswYe3OAdhVnyPusRFX1f0AEBcRrTXAwlIUgJvS7qyIw /issMMzb+FsudypMBNIHpSqdTuyerYNndqDh4vN64/Q0TOZh3uZIrlDKK8msNv/OcnkDK QCEIkqWVlYaH9Lw1OoJ6VqpXlpiCqbnqrQsiHt+TEnLmtXw+i+VPyCJthi3+P6yT9Vg== 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=OkoOF3kH; 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 BB872606A326 for ; Sat, 7 Nov 2026 10:41:11 +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=OkoOF3kH Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0B8791F0089F; Sat, 7 Nov 2026 10:41:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794048071; bh=Nvsa4839TkKWUA7CtpKYp/pQEc9aAk/VAevWqSa2dYc=; h=From:To:Cc:Subject:Date; b=OkoOF3kHKgxXmP4Cpwg2e/gyo/R9uD9vyV6QTQ6kUk4fpWwwvkHKJYQUvTKk/CrVF ce7NVBwHx7MYtTgzpCE6aoGmj8pWwL4y8lAJ/roqPwohuMsdCXk/vMnaHSu1iXgCUS 9xHaEUHMwc29yrOatX0nJL/F4RP11UYzITkNu64/6YVqA0PchFvWQEDznfoGCbQUs4 FFSBCbTDiSq9Qg88YRPJ7gGLM4xmicqyT+TMUt8VTt8bfGMP5YNOvgDb/7nQZwtgvO OWBBLJqFEsBpO6Vmx63M+ZnNKueMGpvoGqFGI3DZk2Rqgo4ljM+VNEjFWPBZN8PEn3 pm5s+bgIgwmMA== 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 6.1-stable tree Date: Sat, 7 Nov 2026 05:41:09 -0500 Message-ID: <20261107054109-failed-6.1-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 6.1-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-6.1.y git checkout FETCH_HEAD git cherry-pick -x eacdb76c5f04956035c5d7f7e1973028f30684a2 # git commit -s git send-email --to '' --in-reply-to '20261107054109-failed-6.1-eacdb76c5f04@kernel.org' --subject-prefix 'PATCH 6.1.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