From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6779EC433F5 for ; Mon, 7 Mar 2022 21:40:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245387AbiCGVl2 (ORCPT ); Mon, 7 Mar 2022 16:41:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39494 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343770AbiCGViH (ORCPT ); Mon, 7 Mar 2022 16:38:07 -0500 Received: from NAM10-BN7-obe.outbound.protection.outlook.com (mail-bn7nam10on2045.outbound.protection.outlook.com [40.107.92.45]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 26B8D6E8E2; Mon, 7 Mar 2022 13:36:08 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=elgpLs8NLLTkxSsH9mRrAIABc2zur0zNMcp1XHu1dyG8De6KYYtxcCdTxEDFaSSLvdAz0Rh9SB9gxVcGqCXDZ7x/pSnvAn5wN3ndRPDPLiS5wcRqwqAzbQ+IylUucaJAvR8Y2pvwyDskYhJwTfVf4GsLkQV28w85abL5IsCCTkLrgN1wTeTTzixb/+EpdbLAXa1VET3wbE4teLKPt+vIItKuWSNjvIDNlVBse/re/KsvMOCDkRKag6dN5pUnY/io3wAQK7KuHWtXMSNDmyM1ju2cS41ppQ8NEs3JN1kzzgYJKWZNknY98JvqXfnatmoEUGZYvlrcPQiLHQWG79U/pQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=lbvaTYmaqxdr+kYYkpTp/E6MXTk5T4w/SS2QoHRoiF4=; b=UWjLPvs+BFqx70Fl406hZGqmaDPAemoB+5KrwBw2qANIGmQqLy+h6iqY/i3ZvsCps9k84Y0BDixPDYuZyMrQAu2AVre2eosn6Ufr1lb8WPkISeM3Vc2z6d6kz/dgbHswKqVAucUhpQpo7C01eauSuwUawlotXLpE3hSKKfcZKM6nbYb7RYbhliMWZ5YVgt3UR1uJXIth1SbahzCVqGFt1zfaHaiMXCr4qdMS5D72ZUPRqW/clEwqVtGkcF102+TZh0TXQBkchW1e+1Pdst53fZqeaeBbsfesEySJoZ3OF0cbdmwEAtSLU8yMGuC61+ufm8Qgu1ni3T2sSaLGyECjaQ== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass (sender ip is 165.204.84.17) smtp.rcpttodomain=kernel.org smtp.mailfrom=amd.com; dmarc=pass (p=quarantine sp=quarantine pct=100) action=none header.from=amd.com; dkim=none (message not signed); arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amd.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=lbvaTYmaqxdr+kYYkpTp/E6MXTk5T4w/SS2QoHRoiF4=; b=x/GshBK7FI9c3LE5tPol/Mvwm5lhxZczX3uU54gigql2vfWZTSRzsl6czyNSTljs9mB6HqrX3fuvojbpqxj0vPI/cdtvBVxUYChLmfnEbNpX1PNzaZrpBY/BgFhSGROSWKn4xLQ5u/IBtih4Sy61z2gNY9fD60/VY8DD+ybeiUw= Received: from BN6PR13CA0051.namprd13.prod.outlook.com (2603:10b6:404:11::13) by BYAPR12MB3479.namprd12.prod.outlook.com (2603:10b6:a03:dc::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5038.14; Mon, 7 Mar 2022 21:35:41 +0000 Received: from BN8NAM11FT015.eop-nam11.prod.protection.outlook.com (2603:10b6:404:11:cafe::9b) by BN6PR13CA0051.outlook.office365.com (2603:10b6:404:11::13) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.5061.3 via Frontend Transport; Mon, 7 Mar 2022 21:35:40 +0000 X-MS-Exchange-Authentication-Results: spf=pass (sender IP is 165.204.84.17) smtp.mailfrom=amd.com; dkim=none (message not signed) header.d=none;dmarc=pass action=none header.from=amd.com; Received-SPF: Pass (protection.outlook.com: domain of amd.com designates 165.204.84.17 as permitted sender) receiver=protection.outlook.com; client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; Received: from SATLEXMB04.amd.com (165.204.84.17) by BN8NAM11FT015.mail.protection.outlook.com (10.13.176.90) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.20.5038.14 via Frontend Transport; Mon, 7 Mar 2022 21:35:40 +0000 Received: from sbrijesh-desktop.amd.com (10.180.168.240) by SATLEXMB04.amd.com (10.181.40.145) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.18; Mon, 7 Mar 2022 15:35:38 -0600 From: Brijesh Singh To: , , , , , , CC: Thomas Gleixner , Ingo Molnar , Joerg Roedel , Tom Lendacky , "H. Peter Anvin" , Ard Biesheuvel , Paolo Bonzini , Sean Christopherson , "Vitaly Kuznetsov" , Jim Mattson , "Andy Lutomirski" , Dave Hansen , Sergio Lopez , Peter Gonda , "Peter Zijlstra" , Srinivas Pandruvada , David Rientjes , Dov Murik , Tobin Feldman-Fitzthum , Borislav Petkov , Michael Roth , Vlastimil Babka , "Kirill A . Shutemov" , Andi Kleen , "Dr . David Alan Gilbert" , , , , , Brijesh Singh Subject: [PATCH v12 46/46] virt: sevguest: Add documentation for SEV-SNP CPUID Enforcement Date: Mon, 7 Mar 2022 15:33:56 -0600 Message-ID: <20220307213356.2797205-47-brijesh.singh@amd.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220307213356.2797205-1-brijesh.singh@amd.com> References: <20220307213356.2797205-1-brijesh.singh@amd.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 2bda279a-0d38-41a5-283e-08da00826d46 X-MS-TrafficTypeDiagnostic: BYAPR12MB3479:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230001)(4636009)(46966006)(36840700001)(40470700004)(316002)(54906003)(110136005)(8676002)(186003)(16526019)(70206006)(70586007)(4326008)(6666004)(7696005)(2906002)(2616005)(36756003)(44832011)(8936002)(5660300002)(7416002)(7406005)(26005)(508600001)(336012)(426003)(356005)(83380400001)(1076003)(81166007)(36860700001)(40460700003)(82310400004)(47076005)(86362001)(36900700001)(2101003);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Mar 2022 21:35:40.4471 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 2bda279a-0d38-41a5-283e-08da00826d46 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: BN8NAM11FT015.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BYAPR12MB3479 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michael Roth Update the documentation with information regarding SEV-SNP CPUID Enforcement details and what sort of assurances it provides to guests. Signed-off-by: Michael Roth Signed-off-by: Brijesh Singh --- Documentation/virt/coco/sevguest.rst | 29 ++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/Documentation/virt/coco/sevguest.rst b/Documentation/virt/coco/sevguest.rst index 0f352056572d..48d66e10305b 100644 --- a/Documentation/virt/coco/sevguest.rst +++ b/Documentation/virt/coco/sevguest.rst @@ -118,6 +118,35 @@ be updated with the expected value. See GHCB specification for further detail on how to parse the certificate blob. +3. SEV-SNP CPUID Enforcement +============================ + +SEV-SNP guests can access a special page that contains a table of CPUID values +that have been validated by the PSP as part of the SNP_LAUNCH_UPDATE firmware +command. It provides the following assurances regarding the validity of CPUID +values: + + - Its address is obtained via bootloader/firmware (via CC blob), and those + binaries will be measured as part of the SEV-SNP attestation report. + - Its initial state will be encrypted/pvalidated, so attempts to modify + it during run-time will result in garbage being written, or #VC exceptions + being generated due to changes in validation state if the hypervisor tries + to swap the backing page. + - Attempts to bypass PSP checks by the hypervisor by using a normal page, or + a non-CPUID encrypted page will change the measurement provided by the + SEV-SNP attestation report. + - The CPUID page contents are *not* measured, but attempts to modify the + expected contents of a CPUID page as part of guest initialization will be + gated by the PSP CPUID enforcement policy checks performed on the page + during SNP_LAUNCH_UPDATE, and noticeable later if the guest owner + implements their own checks of the CPUID values. + +It is important to note that this last assurance is only useful if the kernel +has taken care to make use of the SEV-SNP CPUID throughout all stages of boot. +Otherwise, guest owner attestation provides no assurance that the kernel wasn't +fed incorrect values at some point during boot. + + Reference --------- -- 2.25.1