On Wed, Aug 06, 2025 at 04:02:01PM -0600, Alex Williamson wrote:
On Mon, 4 Aug 2025 16:00:43 +0300 Leon Romanovsky leon@kernel.org wrote:
From: Leon Romanovsky leonro@nvidia.com
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 leonro@nvidia.com
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 <linux/nospec.h> #include <linux/sched/mm.h> #include <linux/iommufd.h> +#include <linux/pci-p2pdma.h> #if IS_ENABLED(CONFIG_EEH) #include <asm/eeh.h> #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 */