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Wed, 06 Aug 2025 15:02:08 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHIzdy8eeJry7tYq6oPCO7e2LCNwpZ/0SyAUMoLDbyTlBwk+OaaK/N75sVSFjgffH+CpRQ7JQ== X-Received: by 2002:a05:6e02:3193:b0:3dd:c927:3b4f with SMTP id e9e14a558f8ab-3e51b8854c1mr22432755ab.2.1754517727346; Wed, 06 Aug 2025 15:02:07 -0700 (PDT) Received: from redhat.com ([38.15.36.11]) by smtp.gmail.com with ESMTPSA id e9e14a558f8ab-3e40297c389sm63783105ab.2.2025.08.06.15.02.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Aug 2025 15:02:05 -0700 (PDT) Date: Wed, 6 Aug 2025 16:02:01 -0600 From: Alex Williamson To: Leon Romanovsky Cc: Leon Romanovsky , Jason Gunthorpe , Andrew Morton , Bjorn Helgaas , Christian =?UTF-8?B?S8O2bmln?= , Christoph Hellwig , dri-devel@lists.freedesktop.org, iommu@lists.linux.dev, Jens Axboe , Joerg Roedel , kvm@vger.kernel.org, linaro-mm-sig@lists.linaro.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, linux-mm@kvack.org, linux-pci@vger.kernel.org, Logan Gunthorpe , Marek Szyprowski , Robin Murphy , Sumit Semwal , Vivek Kasireddy , Will Deacon Subject: Re: [PATCH v1 08/10] vfio/pci: Enable peer-to-peer DMA transactions by default Message-ID: <20250806160201.2b72e7a0.alex.williamson@redhat.com> In-Reply-To: References: Organization: Red Hat Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: -rGQfNP9UoeHznqWJbpHrCxgUSlbVRa90ubVetKYf3k_1754517728 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 4 Aug 2025 16:00:43 +0300 Leon Romanovsky wrote: > From: Leon Romanovsky > > Make sure that all VFIO PCI devices have peer-to-peer capabilities > enables, so we would be able to export their MMIO memory through DMABUF, > > Signed-off-by: Leon Romanovsky > --- > drivers/vfio/pci/vfio_pci_core.c | 4 ++++ > include/linux/vfio_pci_core.h | 1 + > 2 files changed, 5 insertions(+) > > diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c > index 31bdb9110cc0f..df9a32d3deac9 100644 > --- a/drivers/vfio/pci/vfio_pci_core.c > +++ b/drivers/vfio/pci/vfio_pci_core.c > @@ -28,6 +28,7 @@ > #include > #include > #include > +#include > #if IS_ENABLED(CONFIG_EEH) > #include > #endif > @@ -2088,6 +2089,9 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev) > INIT_LIST_HEAD(&vdev->dummy_resources_list); > INIT_LIST_HEAD(&vdev->ioeventfds_list); > INIT_LIST_HEAD(&vdev->sriov_pfs_item); > + vdev->provider = pci_p2pdma_enable(vdev->pdev); > + if (IS_ERR(vdev->provider)) > + return PTR_ERR(vdev->provider); I think this just made all vfio-pci drivers functionally dependent on CONFIG_PCI_P2PDMA. Seems at best exporting a dma-buf should be restricted if this fails. Thanks, Alex > init_rwsem(&vdev->memory_lock); > xa_init(&vdev->ctx); > > diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h > index fbb472dd99b36..b017fae251811 100644 > --- a/include/linux/vfio_pci_core.h > +++ b/include/linux/vfio_pci_core.h > @@ -94,6 +94,7 @@ struct vfio_pci_core_device { > struct vfio_pci_core_device *sriov_pf_core_dev; > struct notifier_block nb; > struct rw_semaphore memory_lock; > + struct p2pdma_provider *provider; > }; > > /* Will be exported for vfio pci drivers usage */