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=1794365008; b=jvJV+nKF6NmpZkLQbeZSarVih+KvT/ZDnOS9w6xBRGURfP8RWZ4YA9dS32kZhOTJInpB kHtSceX28V8p1BzntBQHom1G+zp2bG3Uw1K8oHByuLDKA9oZg8AYmSSmEIVyxbUa4N4FW aUF1Mh67bSWVRTX+Da26+phZCX0CnzGdyWnRKhfuMUGGXB+thFOFeaX9uL0yL2vmkTk45 3jrJvyLtVsNbStnTSh3EoVi2IIWONyGNALqe3olHlqUleKr1mVrrhnyG0/QxydeN+nmZs tehF8Wdk/6Vhhz9C5RpL6mmZaa/tCPsXxxszkw2FyMEoC2Ian0hKcVyathgHJpXi62g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794365008; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=1DY5BdyPwA9XaI5zETr9lVeFfh0ctpw+3FaFqrL5VXs=; b=r1EhTqY0fUj/R3ZVdktpMVvEx9VLiN54yiuXVh617NrG7lPN1tnjcol0V4XphA+5kquH wSU4poUUYiatqL7oOxtaEYxDhHvO2ejeK3aqRiwMnJfNCY0qfLZzOS7x07ff13Y6js0BQ UsqON84o9AmlhSZGpVh9lAvW5Sjm1E5vi7C/2h62lccdrmokND/T0qhZEHUSwwuASjFQj /zAZoNJQDT2VR9p6q4W2Odtl8xIT3MkEcYl5QkkeZahjbJG2d6Ebjtq3dIU/swAM+zuAK ypM8Kk0p8KfSUWM7VkXlH5vg9Q2AJXgVqHjuGDBaUHXkaTt0D3b1L5tREFFjWqJsIkw== 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=Ld2YSjeM; 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 070CA606A32E for ; Wed, 11 Nov 2026 02:43:28 +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=Ld2YSjeM Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A0E51F00A03; Wed, 11 Nov 2026 02:43:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794365007; bh=1DY5BdyPwA9XaI5zETr9lVeFfh0ctpw+3FaFqrL5VXs=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Ld2YSjeMcdEuG2R6qQf5O2SW6DvaPxjcdAzYIchwSgul3CWzFv/tXuM5V19pDaLCG 6c/kRc0yQ766+2P2L5jkU2z80VNrv56aTQTgZSMnjpULRA09F5iq0GSd+eBAqkvs2V Qx4rdnmo/DZFKgBx/35ha4OxAZJZLF5BlGaqZ/p1wL0h8NhdmZBDo+UD3HfAcy+H5y wkcNomLxfKk+SZuxb2lw9iX73PzLLhuhGm1fIQQyz+TCYCYGdfWolEMUgF3/J/K8Cj UW9bzfcUj/JtfriScBVY/lMvlqnKI85ftM8tVqh/OfEl2+KyFXky5oWV4mFqYWxMf8 XyLav56G9mISw== From: Sasha Levin To: stable@vger.kernel.org Cc: David Woodhouse , sashiko-bot@kernel.org, Paul Durrant , Paolo Bonzini , Sasha Levin Subject: [PATCH 6.6.y 5/5] KVM: x86/xen: Enforce 4-byte alignment of vcpu_info registration Date: Tue, 10 Nov 2026 21:43:23 -0500 Message-ID: <20261111024039.676658-5-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261111024039.676658-1-sashal@kernel.org> References: <20261107052838-failed-6.6-eacdb76c5f04@kernel.org> <20261111024039.676658-1-sashal@kernel.org> 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-Transfer-Encoding: 8bit From: David Woodhouse [ Upstream commit eacdb76c5f04956035c5d7f7e1973028f30684a2 ] 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 [ sashal: Omitted the HVA alignment check because only GPA registration is supported. ] Signed-off-by: Sasha Levin --- arch/x86/kvm/xen.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 335e046c68365..9dad266350609 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -742,6 +742,10 @@ 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)); if (!r) -- 2.53.0