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Thu, 21 Dec 2023 07:40:23 -0800 From: To: , , , , , , , , , , , , , , , CC: , , , , , , , , , , , , , Subject: [PATCH v5 2/4] mm: introduce new flag to indicate wc safe Date: Thu, 21 Dec 2023 21:10:00 +0530 Message-ID: <20231221154002.32622-3-ankita@nvidia.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20231221154002.32622-1-ankita@nvidia.com> References: <20231221154002.32622-1-ankita@nvidia.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN1PEPF00026367:EE_|DS0PR12MB7770:EE_ X-MS-Office365-Filtering-Correlation-Id: 97e4db02-b274-461b-048c-08dc023b3360 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:216.228.117.160;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge1.nvidia.com;CAT:NONE;SFS:(13230031)(4636009)(396003)(39860400002)(376002)(346002)(136003)(230922051799003)(64100799003)(451199024)(1800799012)(82310400011)(186009)(40470700004)(46966006)(36840700001)(356005)(7636003)(82740400003)(41300700001)(86362001)(8676002)(8936002)(83380400001)(4326008)(70206006)(70586007)(54906003)(110136005)(426003)(336012)(7416002)(316002)(40480700001)(5660300002)(2876002)(2906002)(47076005)(478600001)(36756003)(6666004)(7696005)(26005)(1076003)(2616005)(921008)(40460700003)(36860700001)(2101003)(83996005);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Dec 2023 15:40:46.6774 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 97e4db02-b274-461b-048c-08dc023b3360 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: SN1PEPF00026367.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS0PR12MB7770 From: Ankit Agrawal Generalizing S2 setting from DEVICE_nGnRE to NormalNc for non PCI devices may be problematic. E.g. GICv2 vCPU interface, which is effectively a shared peripheral, can allow a guest to affect another guest's interrupt distribution. The issue may be solved by limiting the relaxation to mappings that have a user VMA. Still there is insufficient information and uncertainity in the behavior of non PCI drivers. Add a new flag VM_VFIO_ALLOW_WC to indicate KVM that the device is WC capable and these S2 changes can be extended to it. KVM can use this flag to activate the code. Signed-off-by: Ankit Agrawal Suggested-by: Catalin Marinas Acked-by: Jason Gunthorpe Tested-by: Ankit Agrawal --- include/linux/mm.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/include/linux/mm.h b/include/linux/mm.h index 418d26608ece..49277e845b21 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -391,6 +391,20 @@ extern unsigned int kobjsize(const void *objp); # define VM_UFFD_MINOR VM_NONE #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ +/* + * This flag is used to connect VFIO to arch specific KVM code. It + * indicates that the memory under this VMA is safe for use with any + * non-cachable memory type inside KVM. Some VFIO devices, on some + * platforms, are thought to be unsafe and can cause machine crashes if + * KVM does not lock down the memory type. + */ +#ifdef CONFIG_64BIT +#define VM_VFIO_ALLOW_WC_BIT 39 +#define VM_VFIO_ALLOW_WC BIT(VM_VFIO_ALLOW_WC_BIT) +#else +#define VM_VFIO_ALLOW_WC VM_NONE +#endif + /* Bits set in the VMA until the stack is in its final location */ #define VM_STACK_INCOMPLETE_SETUP (VM_RAND_READ | VM_SEQ_READ | VM_STACK_EARLY)