[PATCH v1 08/10] vfio/pci: Enable peer-to-peer DMA transactions by default

Leon Romanovsky
2025-08-04T13:01:41Z

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);
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 */
--
2.50.1