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b=Y03rLipQ172HNCWdzae1SvWeUKEZCuyy4iT/sxqmRUG2Mk9XAm0JD2Cf43Q4ccXI4 vJ3zCW+7bhV2I/8W3AQ/zj+cPA9rZhBtVccOf2Syvu2xP3GZZOcRUzTwD1l9Dszm61 coTmrjtssASLghJ0YobZBbn3b5yvo1gmHUuMYKl3N+eOUDvW9dLkEd42uz6ExoscbL AN9nGwSWGJAg2aXnrk/T8mIOnh8SJFTLZoRnFwoAw9p/ZVbj1um54ETkG1UmVJ0yaX k1mi0ufFXvprbr0GmTrnZJZPMNtSonfXc/UWWvtDhkzWmzN/ZJ+J57M3aRwqpyvkrT ePb8jIU/SceyA== Date: Tue, 2 Sep 2025 15:58:24 +0300 From: Leon Romanovsky To: Alex Williamson Cc: Jason Gunthorpe , Andrew Morton , Bjorn Helgaas , Christian =?iso-8859-1?Q?K=F6nig?= , 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: <20250902125824.GH10073@unreal> References: <20250806160201.2b72e7a0.alex.williamson@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250806160201.2b72e7a0.alex.williamson@redhat.com> X-Rspamd-Queue-Id: D21B910000A X-Rspamd-Server: rspam04 X-Rspam-User: X-Stat-Signature: 4tfftib31iu7a1gjxqff391a69x9u6ew X-HE-Tag: 1756817910-28248 X-HE-Meta: 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 fRw== 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: On Wed, Aug 06, 2025 at 04:02:01PM -0600, Alex Williamson wrote: > 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, It is temporary solution in next patch "vfio/pci: Add dma-buf export support for MMIO regions", the strict ifdef is added. 2107 #ifdef CONFIG_VFIO_PCI_DMABUF 2108 vdev->provider = pci_p2pdma_enable(vdev->pdev); 2109 if (IS_ERR(vdev->provider)) 2110 return PTR_ERR(vdev->provider); 2111 2112 INIT_LIST_HEAD(&vdev->dmabufs); 2113 #endif I will split "vfio/pci: Add dma-buf export ..." patch to introduce CONFIG_VFIO_PCI_DMABUF before this "vfio/pci: Enable peer-to-peer ..." patch. 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 */ >