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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: SA1PR12MB7199.namprd12.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 88738be0-af42-418d-280b-08de28597a08 X-MS-Exchange-CrossTenant-originalarrivaltime: 20 Nov 2025 17:23:09.6878 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: KC7D/VTeVrmvf6/f0WMVdoJULq3MysawiYlZxIvbVml3VZ7rbr5VCWe3ZVIDsOt01CZgA3sUzKBrwXOKvr1dWA== X-MS-Exchange-Transport-CrossTenantHeadersStamped: MN0PR12MB6126 X-Rspamd-Queue-Id: 32EF5180020 X-Rspamd-Server: rspam07 X-Stat-Signature: c1uxcxcqidsfpzpqrd6bp79bgs4yrqjo X-Rspam-User: X-HE-Tag: 1763659394-805163 X-HE-Meta: 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 xFH1GRWP 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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: > This series extends the VFIO PCI subsystem to support exporting MMIO=0A= > regions from PCI device BARs as dma-buf objects, enabling safe sharing of= =0A= > non-struct page memory with controlled lifetime management. This allows R= DMA=0A= > and other subsystems to import dma-buf FDs and build them into memory reg= ions=0A= > for PCI P2P operations.=0A= >=0A= > The series supports a use case for SPDK where a NVMe device will be=0A= > owned by SPDK through VFIO but interacting with a RDMA device. The RDMA= =0A= > device may directly access the NVMe CMB or directly manipulate the NVMe= =0A= > device's doorbell using PCI P2P.=0A= >=0A= > However, as a general mechanism, it can support many other scenarios with= =0A= > VFIO. This dmabuf approach can be usable by iommufd as well for generic= =0A= > and safe P2P mappings.=0A= >=0A= > In addition to the SPDK use-case mentioned above, the capability added=0A= > in this patch series can also be useful when a buffer (located in device= =0A= > memory such as VRAM) needs to be shared between any two dGPU devices or= =0A= > instances (assuming one of them is bound to VFIO PCI) as long as they=0A= > are P2P DMA compatible.=0A= >=0A= > The implementation provides a revocable attachment mechanism using dma-bu= f=0A= > move operations. MMIO regions are normally pinned as BARs don't change=0A= > physical addresses, but access is revoked when the VFIO device is closed= =0A= > or a PCI reset is issued. This ensures kernel self-defense against=0A= > potentially hostile userspace.=0A= >=0A= > The series includes significant refactoring of the PCI P2PDMA subsystem= =0A= > to separate core P2P functionality from memory allocation features,=0A= > making it more modular and suitable for VFIO use cases that don't need=0A= > struct page support.=0A= >=0A= > -----------------------------------------------------------------------= =0A= > The series is based originally on=0A= > https://lore.kernel.org/all/20250307052248.405803-1-vivek.kasireddy@intel= .com/=0A= > but heavily rewritten to be based on DMA physical API.=0A= > -----------------------------------------------------------------------= =0A= > The WIP branch can be found here:=0A= > https://git.kernel.org/pub/scm/linux/kernel/git/leon/linux-rdma.git/log/?= h=3Ddmabuf-vfio-v9=0A= =0A= Acked-by: Ankit Agrawal =