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Sat, 18 Jun 2022 23:41:32 -0700 Date: Sat, 18 Jun 2022 23:41:30 -0700 From: Nicolin Chen To: Christoph Hellwig , CC: , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , Subject: Re: [RFT][PATCH v1 6/6] vfio: Replace phys_pfn with phys_page for vfio_pin_pages() Message-ID: References: <20220616235212.15185-1-nicolinc@nvidia.com> <20220616235212.15185-7-nicolinc@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: ed3a46ed-fcdd-4fba-8af8-08da51bec12d X-MS-TrafficTypeDiagnostic: BL0PR12MB2497: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:12.22.5.235;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:InfoNoRecords;CAT:NONE;SFS:(13230016)(4636009)(40470700004)(46966006)(36840700001)(356005)(7406005)(81166007)(70586007)(8676002)(7416002)(6636002)(316002)(498600001)(110136005)(54906003)(5660300002)(8936002)(4326008)(70206006)(40460700003)(186003)(86362001)(82310400005)(2906002)(9686003)(47076005)(336012)(36860700001)(83380400001)(55016003)(26005)(33716001)(426003)(36900700001);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Jun 2022 06:41:35.1720 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ed3a46ed-fcdd-4fba-8af8-08da51bec12d X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[12.22.5.235];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT053.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR12MB2497 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 18, 2022 at 11:18:17PM -0700, Christoph Hellwig wrote: > > > There is a bunch of code an comments in the iommu type1 code that > > > suggest we can pin memory that is not page backed. > > > > Would you mind explaining the use case for pinning memory that > > isn't page backed? And do we have such use case so far? > > Sorry, I should have deleted that sentence. I wrote it before spending > some more time to dig through the code and all the locked memory has > page backing. There just seem to be a lot of checks left inbetween > if a pfn is page backed, mostly due to the pfn based calling convetions. OK. We'd be safe to move on then. Thanks for the clarification. > > I can do that. I tried once, but there were just too much changes > > inside type1 code that felt like a chain reaction. If we plan to > > eventually replace with IOMMUFD implementations, these changes in > > type1 might not be necessary, I thought. > > To make sure we keep full compatibility I suspect the final iommufd > implementation has to be gradutally created from the existing code > anyway. Hmm. I think Jason can give some insight. Meanwhile, I will try to add a patch to type1 code, in case we'd end up with what you suspected. 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Sat, 18 Jun 2022 23:41:32 -0700 Date: Sat, 18 Jun 2022 23:41:30 -0700 From: Nicolin Chen To: Christoph Hellwig , Subject: Re: [RFT][PATCH v1 6/6] vfio: Replace phys_pfn with phys_page for vfio_pin_pages() Message-ID: References: <20220616235212.15185-1-nicolinc@nvidia.com> <20220616235212.15185-7-nicolinc@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: ed3a46ed-fcdd-4fba-8af8-08da51bec12d X-MS-TrafficTypeDiagnostic: BL0PR12MB2497: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:12.22.5.235; CTRY:US; LANG:en; SCL:1; SRV:; IPV:NLI; SFV:NSPM; H:mail.nvidia.com; PTR:InfoNoRecords; CAT:NONE; SFS:(13230016)(4636009)(40470700004)(46966006)(36840700001)(356005)(7406005)(81166007)(70586007)(8676002)(7416002)(6636002)(316002)(498600001)(110136005)(54906003)(5660300002)(8936002)(4326008)(70206006)(40460700003)(186003)(86362001)(82310400005)(2906002)(9686003)(47076005)(336012)(36860700001)(83380400001)(55016003)(26005)(33716001)(426003)(36900700001); DIR:OUT; SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Jun 2022 06:41:35.1720 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: ed3a46ed-fcdd-4fba-8af8-08da51bec12d X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a; Ip=[12.22.5.235]; Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1NAM11FT053.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BL0PR12MB2497 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mjrosato@linux.ibm.com, linux-doc@vger.kernel.org, airlied@linux.ie, kevin.tian@intel.com, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kwankhede@nvidia.com, vneethv@linux.ibm.com, agordeev@linux.ibm.com, linux-s390@vger.kernel.org, kvm@vger.kernel.org, corbet@lwn.net, pasic@linux.ibm.com, borntraeger@linux.ibm.com, intel-gfx@lists.freedesktop.org, zhi.a.wang@intel.com, jjherne@linux.ibm.com, farman@linux.ibm.com, jchrist@linux.ibm.com, gor@linux.ibm.com, hca@linux.ibm.com, alex.williamson@redhat.com, freude@linux.ibm.com, rodrigo.vivi@intel.com, intel-gvt-dev@lists.freedesktop.org, akrowiak@linux.ibm.com, tvrtko.ursulin@linux.intel.com, cohuck@redhat.com, oberpar@linux.ibm.com, svens@linux.ibm.com Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Sat, Jun 18, 2022 at 11:18:17PM -0700, Christoph Hellwig wrote: > > > There is a bunch of code an comments in the iommu type1 code that > > > suggest we can pin memory that is not page backed. > > > > Would you mind explaining the use case for pinning memory that > > isn't page backed? And do we have such use case so far? > > Sorry, I should have deleted that sentence. I wrote it before spending > some more time to dig through the code and all the locked memory has > page backing. There just seem to be a lot of checks left inbetween > if a pfn is page backed, mostly due to the pfn based calling convetions. OK. We'd be safe to move on then. Thanks for the clarification. > > I can do that. I tried once, but there were just too much changes > > inside type1 code that felt like a chain reaction. If we plan to > > eventually replace with IOMMUFD implementations, these changes in > > type1 might not be necessary, I thought. > > To make sure we keep full compatibility I suspect the final iommufd > implementation has to be gradutally created from the existing code > anyway. Hmm. I think Jason can give some insight. Meanwhile, I will try to add a patch to type1 code, in case we'd end up with what you suspected.