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charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: BN9PR11MB5276.namprd11.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1f8e64d2-2791-4bc4-8937-08dcb2ccda66 X-MS-Exchange-CrossTenant-originalarrivaltime: 02 Aug 2024 08:26:48.6885 (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: YUgTXdmJiwm0xxsYGPPAn8THIoqzkUXzfUn8JqfVK57b6g0EUaOlDthfawGLNsJ7aOUYjDnebpmQHvk+wDbrUw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR11MB8380 X-OriginatorOrg: intel.com X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 12F8A140017 X-Stat-Signature: 3ny95o9mimewycqs1ir5pc64i5673me7 X-HE-Tag: 1722587216-633712 X-HE-Meta: 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 +nteCOE5 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > From: Jason Gunthorpe > Sent: Thursday, June 20, 2024 10:34 PM >=20 > On Thu, Jun 20, 2024 at 04:14:23PM +0200, David Hildenbrand wrote: >=20 > > 1) How would the device be able to grab/access "private memory", if not > > via the user page tables? >=20 > The approaches I'm aware of require the secure world to own the IOMMU > and generate the IOMMU page tables. So we will not use a GUP approach > with VFIO today as the kernel will not have any reason to generate a > page table in the first place. Instead we will say "this PCI device > translates through the secure world" and walk away. >=20 > The page table population would have to be done through the KVM path. >=20 Sorry for noting this discussion late. Dave pointed it to me in a related thread [1]. I had an impression that above approach fits some trusted IO arch (e.g. TDX Connect which has a special secure I/O page table format and requires sharing it between IOMMU/KVM) but not all. e.g. SEV-TIO spec [2] (page 8) describes to have the IOMMU walk the existing I/O page tables to get HPA and then verify it through a new permission table (RMP) for access control. That arch may better fit a scheme in which the I/O page tables are still managed by VFIO/IOMMUFD and RMP is managed by KVM, with an an extension to the MAP_DMA call to accept a [guest_memfd, offset] pair to find out the pfn instead of using host virtual address. looks the Linux MM alignment session [3] did mention "guest_memfd will take ownership of the hugepages, and provide interested parties (userspace, KVM, iommu) with pages to be used" to support that extension? [1] https://lore.kernel.org/kvm/272e3dbf-ed4a-43f5-8b5f-56bf6d74930c@redhat= .com/ [2] https://www.amd.com/system/files/documents/sev-tio-whitepaper.pdf [3] https://lore.kernel.org/kvm/20240712232937.2861788-1-ackerleytng@google= .com/ Thanks Kevin