[PATCH v5 8/9] vfio/pci: Enable peer-to-peer DMA transactions by default

Leon Romanovsky
2025-10-13T15:26:55Z

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 | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index ca9a95716a85..fe247d0e2831 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
@@ -2081,6 +2082,7 @@ 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 ret;

vdev->pdev = to_pci_dev(core_vdev->dev);
vdev->irq_type = VFIO_PCI_NUM_IRQS;
@@ -2090,6 +2092,9 @@ 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);
+ ret = pcim_p2pdma_init(vdev->pdev);
+ if (ret != -EOPNOTSUPP)
+ return ret;
init_rwsem(&vdev->memory_lock);
xa_init(&vdev->ctx);

--
2.51.0