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Wed, 22 May 2024 03:25:12 +0000 Received: from DS7PR11MB5966.namprd11.prod.outlook.com ([fe80::e971:d8f4:66c4:12ca]) by DS7PR11MB5966.namprd11.prod.outlook.com ([fe80::e971:d8f4:66c4:12ca%6]) with mapi id 15.20.7587.030; Wed, 22 May 2024 03:25:12 +0000 Date: Wed, 22 May 2024 11:24:20 +0800 From: Yan Zhao To: Jason Gunthorpe CC: Alex Williamson , "Tian, Kevin" , "Vetter, Daniel" , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "x86@kernel.org" , "iommu@lists.linux.dev" , "pbonzini@redhat.com" , "seanjc@google.com" , "dave.hansen@linux.intel.com" , "luto@kernel.org" , "peterz@infradead.org" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "hpa@zytor.com" , "corbet@lwn.net" , "joro@8bytes.org" , "will@kernel.org" , "robin.murphy@arm.com" , "baolu.lu@linux.intel.com" , "Liu, Yi L" Subject: Re: [PATCH 4/5] vfio/type1: Flush CPU caches on DMA pages in non-coherent domains Message-ID: Reply-To: Yan Zhao References: <20240510105728.76d97bbb.alex.williamson@redhat.com> <20240516143159.0416d6c7.alex.williamson@redhat.com> <20240517171117.GB20229@nvidia.com> <20240521160714.GJ20229@nvidia.com> <20240521102123.7baaf85a.alex.williamson@redhat.com> <20240521163400.GK20229@nvidia.com> Content-Type: text/plain; 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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?9zjrcEANPTTU7eoxBVtzOU50JQe8TNDMHj9/0epyly5fFsRxD+BTgZCE5J3v?= =?us-ascii?Q?77B8RTqaHyP0lZHwI5ZubVPHwC6d6FpqmMz5vJ0rbGaAIJcEbbD7tLbOO/1A?= =?us-ascii?Q?bliI/GMsRZrh0DUluF58kBdPUA0Kaq2cXxylQ2S23LvdbWfdULlM2udKo20a?= =?us-ascii?Q?t73EIUFKRzFYmpZPIFtHZqJ28X0/B+q5cro2vLWcm7i25nIdiJDhtAFOrU5A?= =?us-ascii?Q?OVhHyC26lI0J7YakMFvBGZ/nUQmRL/z7+lV9uXDMp1GrckBxf2HVRX/5qMgk?= =?us-ascii?Q?qQcEfhStIxm3Oq/WPif57GUefGVJX+ZjgFiutD21b2iIGM7IDUNMkEC79M0V?= =?us-ascii?Q?0nm3592MyFeplGVTf7jRzsxt1rxbNM2VsABK+kLBY5GFR86/tgaRKjVJ+pBH?= =?us-ascii?Q?G/1F5MYFgtFzjA9ekwVQvflguRGJuRGLS2brQrroHrIp3SnsDaryJ17ZMoxk?= =?us-ascii?Q?sKpUGDvmqRkajW1yQE31eG2A8fCKYgkOcd7JGFqsuUawyiAgHRCv8BXiaG0H?= =?us-ascii?Q?PwL7CJeEnDbEdCwTD9HqsXQUMyS1rIK/zh23KTn/yKHD/W5zILU5YfAmkFQW?= =?us-ascii?Q?DSxF1wTyiCSukQlLo97z4IHkhZQP4lroCpgblEm8Y7Pr411dJ1v9pfQP9FaM?= =?us-ascii?Q?tqV3KwSKxRKQ1Ruv1SlTKrAjFuyFTgoGjIZFL9k2KSyQ0f9xlADbUo6goQXV?= =?us-ascii?Q?KgInSzxxPN9AKbBpEDTcqC9kypfA7ytWEKfzmto+ANIbFfjSaFoBSYdz/ECk?= =?us-ascii?Q?2r683skWYMgvJEbM4bD1XjUGKV+RK3otFpcWVmTQUukc5Uy6eGxu10TNQnF1?= =?us-ascii?Q?FAg6o5aUJLRgg6Kxj3qgoES/cGIiObR2CHwQz1aIXkhCEoBC7Ap7ofNg5l+8?= =?us-ascii?Q?Or+otUJfuF/021TURGGDe+/BI6eRV3+S1Cn/lLWrawr4F7fWFsv+2aZKH8HX?= =?us-ascii?Q?lOPdvqqlaG6H24faNRaHnLISj2q/w6pPOaVk23crhSkXJuDyJCGg2drvixxx?= =?us-ascii?Q?Mfzt8bqCLdBA4soNMzlc4aQtXGTLcL5pyXOfO/dU84d9yyEF1iabC7cpXkaL?= =?us-ascii?Q?+zcxRGTPWLdAsBa1exPNgF2Zwd7mEQUlVM7Y4/N6/2gjJONVqf6N0KkZQXGL?= =?us-ascii?Q?Fwhsvu57zg+rdjtNxIsopskneJxPBDVqBj1uj46CoFruNS+9hPDaPDdZj+yq?= =?us-ascii?Q?GuWjJ0L5RUvKuMERzM29zGvXLGPL4g8p6TSw/k3RmCA2nOTJWhLXP8j06SEq?= =?us-ascii?Q?9+pf6ayzOYFAJbA35t5pIXOSdplwK3snSSIpazNh0d1DaUQq4ZE84ym3CTLh?= =?us-ascii?Q?eQ8rHEEMY1pXa/l75tIkh9HGm1RBQz8lrvrwxkcgN9o8EnFES/f7K4ox9RuL?= =?us-ascii?Q?/sdSWt20/ByS1A0hxQp7FZ6RQ1c9y/W990X8xxvUZzV54+kSn0od6LGutJTn?= =?us-ascii?Q?NzwmYCCAoap3/12qLHcG7ccjotdM/fiHEg+/yrG7znfr2p6LW6ND25r90z5C?= =?us-ascii?Q?VIVtmDLfU6FPu3nzmSMDahxfCH8DOrmB1RNywqUKAcTWfMeny87iS78Kk0wr?= =?us-ascii?Q?WS19rgR/N7DO54PLebLGRqmXLBj1+ceH3oFNmghn?= X-MS-Exchange-CrossTenant-Network-Message-Id: 4f5f9af5-e9b2-4bdf-63b5-08dc7a0eca63 X-MS-Exchange-CrossTenant-AuthSource: DS7PR11MB5966.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 22 May 2024 03:25:12.4706 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 4+Jyv/5WrjKFATA1djyz1T9vU+3SNQrwg8f2R/MoFVT7mJkwmoSUubXgiaA1vp+yGyPlSwpkGgzQtjGP37IRxg== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR11MB6903 X-OriginatorOrg: intel.com On Tue, May 21, 2024 at 01:34:00PM -0300, Jason Gunthorpe wrote: > On Tue, May 21, 2024 at 10:21:23AM -0600, Alex Williamson wrote: > > > > Intel GPU weirdness should not leak into making other devices > > > insecure/slow. If necessary Intel GPU only should get some variant > > > override to keep no snoop working. > > > > > > It would make alot of good sense if VFIO made the default to disable > > > no-snoop via the config space. > > > > We can certainly virtualize the config space no-snoop enable bit, but > > I'm not sure what it actually accomplishes. We'd then be relying on > > the device to honor the bit and not have any backdoors to twiddle the > > bit otherwise (where we know that GPUs often have multiple paths to get > > to config space). > > I'm OK with this. If devices are insecure then they need quirks in > vfio to disclose their problems, we shouldn't punish everyone who > followed the spec because of some bad actors. Does that mean a malicous device that does not honor the bit could read uninitialized host data?