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Peter Anvin" , Tom Lendacky , Nikunj A Dadhania , Ard Biesheuvel , Ashish Kalra , Dionna Glaze , Michael Roth , "Kuppuswamy Sathyanarayanan" , "Alexey Kardashevskiy" Subject: [PATCH v2 3/4] x86/sev: Document requirement for linear mapping of Guest Request buffers Date: Wed, 11 Jun 2025 14:08:41 +1000 Message-ID: <20250611040842.2667262-4-aik@amd.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250611040842.2667262-1-aik@amd.com> References: <20250611040842.2667262-1-aik@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable 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-TrafficTypeDiagnostic: CH3PEPF00000013:EE_|SA0PR12MB4381:EE_ X-MS-Office365-Filtering-Correlation-Id: 194cdd54-d0c7-4841-b921-08dda89dcfdc X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|1800799024|36860700013|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?xRetMoBJ1aqOqwRDEh0z7+hQY9bAlWbNa4pxwBEFNKsOlyefB86SzD/fntWt?= =?us-ascii?Q?ww/kPETJ8zOA45NmMP96d3winkXCiDipPb4Q9G8Z/CC6cIPLZA/SeebpYKCH?= =?us-ascii?Q?2Ps6CEJ3cnnbUOIAodpy2lAlJdCMIOmfowZKA3MYpi2u4iIxVx2pw/CC+yLz?= =?us-ascii?Q?lmdc/Q0qn3LgGz41pDnr5khzkL1tY4cIXIH849TTM5G+mPh5PmI9R+pZoqZo?= =?us-ascii?Q?AlbXa+R5Ha9WnjaNxIvkV2Cgsxmc6WToHr04WLLuA4T9+c66s45bCKt2RfAL?= =?us-ascii?Q?TfSkJgTwnNY79NZ29CrHe9z2/ZkXm+nIHbd08pP0cxrYGsRVelYlt6PkdPq9?= =?us-ascii?Q?jW5OPWsG/yUqelPxrsAMieryohgBU3YqNDozxYT4iz+1C/5Vn4CV+0zYcfEQ?= =?us-ascii?Q?7k6MgsLxf5lRVVSePdCWFO+gAyVGVDQhIYqxRMbKN6i9/OFuweRCGSUczjjA?= =?us-ascii?Q?HBfOaELb34YNhGyZK0ujyIcmNHMQ1p/Ydu1ZptF/eT3/8RUnJa/NtUFn+WYW?= =?us-ascii?Q?3cy0JdaKDCw0VA3+yUEODzX06VLvE0/PbAuyZmguHx8+4OcwK+rKWmK6Um4f?= =?us-ascii?Q?i152KdNRRdahZUR46k5xfBVbq62sV6hGvncTj9r2pp+fR68DDJgb9HikShzL?= =?us-ascii?Q?3uXa89dCkO/Ti5hQ4PmokGNU4d1F5ef1WMKdjdmwhCR9+kDW15dVnqpSw4ze?= =?us-ascii?Q?vaYox5/xUnY/Bic7kvwNAvMtGbFFS6E1PrzqFY1JW88dMWtrunL529ZjANL/?= =?us-ascii?Q?+42Ew4YxD2dZZ2IGELPLE2L2afbqvhZomINzW3hsDLqPoIzF+7sIXJxVmHNR?= =?us-ascii?Q?8e1Hn2qZxf9PHTO7KMOkV1FXAzTw99zn4FZVDb44QyjG1KQg9N9XIJETtXzD?= =?us-ascii?Q?JMi/MS6mVefztg2S+R2f8td8AIBS0cPkMPz70L+eWHpkcSUZvjtkB/cIh972?= =?us-ascii?Q?/urHqnKK4hgrkiu5gk9l4XkG2MC8SocJJoVg9c5pYc6pvwamX0EnKq3LVBlG?= =?us-ascii?Q?buF0cGCGYH0O8IJPQ6YsijtoSddDPVCqxGotFiEcVhRMhxUWd5tDFo76roTC?= =?us-ascii?Q?XEosSLxGS7hMyKWjshxItKIuTp584eatqJ/y85OcM0OuZvMzNezwvBTof34r?= =?us-ascii?Q?WKkhbg3L5TDQzH+rLb0cUAKDAwydh/OE6ltu1u62wf302wBGng+ywno/PYPa?= =?us-ascii?Q?FIFEe/D+zKYtkQERhN873R63XMzWBED/RtKtFfy9IvfjlL6H6XzRccs4XO2h?= =?us-ascii?Q?bkZE/d9IdJ5xU/RQ4mMzQD6LVmnc1diAj374emsBAC2zjxCw1ayjRDLvkIK/?= =?us-ascii?Q?PmtmUm1oPezD8RbcxTFaqACh8BkrgApGK+YDbx0W020JpkLl0cgjS6vTmSBE?= =?us-ascii?Q?NYwqnWFRoegPsznuuQoNnbZiDyU33k4I5U++0Ej3N8NS/4AnMoTNJW8k1VOw?= =?us-ascii?Q?pYwnK4zB6cWxYFf2QjqmG9qdaRpHubSWTIRuBAcGRM72SIB9T4lW1sgoNkoq?= =?us-ascii?Q?he8icTQ9LWiF1hte2wTzLMTPrcjKS/62oZ5S?= 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:(13230040)(376014)(7416014)(1800799024)(36860700013)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 Jun 2025 04:09:50.6576 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 194cdd54-d0c7-4841-b921-08dda89dcfdc 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: CH3PEPF00000013.namprd21.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA0PR12MB4381 Content-Type: text/plain; charset="utf-8" The Guest Request supports 3 types of messages now, the largest is the extended variant of MSG_REPORT_REQ: sizeof(snp_ext_report_req)=3D=3D112. These used to be allocated on stack and then moved to the SNP guest platform device (snp_guest_dev) for the reason explained in commit db10cb9b5746 ("virt: sevguest: Fix passing a stack buffer as a scatterlist target"): aesgcm_encrypt() and aesgcm_decrypt() are used for guest messages and might potentially use a crypto accelerator which requires DMA buffers to be in the linear mapping. Add a comment, pr_warn() and return -EINVAL when the buffers are not in linear mapping. Reviewed-by: Tom Lendacky Reviewed-by: Dionna Glaze Signed-off-by: Alexey Kardashevskiy --- Changes: v2: * adjust grammar --- arch/x86/coco/sev/core.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index 068653865bfb..b0d423a353ab 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -2008,6 +2008,15 @@ int snp_send_guest_request(struct snp_msg_desc *mdes= c, struct snp_guest_req *req u64 seqno; int rc; =20 + /* + * enc_payload() calls aesgcm_encrypt(), which can potentially offload to= HW. + * The offload's DMA SG list of data to encrypt has to be in linear mappi= ng. + */ + if (!virt_addr_valid(req->req_buf) || !virt_addr_valid(req->resp_buf)) { + pr_warn("AES-GSM buffers must be in linear mapping"); + return -EINVAL; + } + guard(mutex)(&snp_cmd_mutex); =20 /* Check if the VMPCK is not empty */ --=20 2.49.0