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Mon, 29 Sep 2025 14:17:48 -0700 (PDT) X-Google-Smtp-Source: AGHT+IHE31/4ZuuqxcHY5C8RvKg6dnDpxm6QWjHiIpet9IRXNGlsIsGmjCxy18kHCIW8dgbK0MWZ9w== X-Received: by 2002:a05:6e02:1b08:b0:424:6c8e:6187 with SMTP id e9e14a558f8ab-425955e4dfdmr95833605ab.2.1759180667942; Mon, 29 Sep 2025 14:17:47 -0700 (PDT) Received: from redhat.com ([38.15.36.11]) by smtp.gmail.com with ESMTPSA id 8926c6da1cb9f-5753c50a188sm920778173.31.2025.09.29.14.17.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 29 Sep 2025 14:17:46 -0700 (PDT) Date: Mon, 29 Sep 2025 15:17:45 -0600 From: Alex Williamson To: Leon Romanovsky Cc: Leon Romanovsky , Jason Gunthorpe , Andrew Morton , Bjorn Helgaas , Christian =?UTF-8?B?S8O2bmln?= , 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 v4 08/10] vfio/pci: Enable peer-to-peer DMA transactions by default Message-ID: <20250929151745.439be1ec.alex.williamson@redhat.com> In-Reply-To: References: X-Mailer: Claws Mail 4.3.1 (GTK 3.24.43; x86_64-redhat-linux-gnu) 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: Go11bNTG9QV2o0qAkZNGnPYXOUlqO4QJVO7LrQ4XaFw_1759180668 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 28 Sep 2025 17:50:18 +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 | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c > index 7dcf5439dedc..608af135308e 100644 > --- a/drivers/vfio/pci/vfio_pci_core.c > +++ b/drivers/vfio/pci/vfio_pci_core.c > @@ -28,6 +28,9 @@ > #include > #include > #include > +#ifdef CONFIG_VFIO_PCI_DMABUF > +#include > +#endif > #if IS_ENABLED(CONFIG_EEH) > #include > #endif > @@ -2085,6 +2088,7 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev) > { > struct vfio_pci_core_device *vdev = > container_of(core_vdev, struct vfio_pci_core_device, vdev); > + int __maybe_unused ret; > > vdev->pdev = to_pci_dev(core_vdev->dev); > vdev->irq_type = VFIO_PCI_NUM_IRQS; > @@ -2094,6 +2098,11 @@ 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); > +#ifdef CONFIG_VFIO_PCI_DMABUF > + ret = pcim_p2pdma_init(vdev->pdev); > + if (ret) > + return ret; > +#endif > init_rwsem(&vdev->memory_lock); > xa_init(&vdev->ctx); > What breaks if we don't test the return value and remove all the #ifdefs? The feature call should fail if we don't have a provider but that seems more robust than failing to register the device. Thanks, Alex