Since converting BAR mmap()s to using DMABUFs, we lose the original device path in /proc/<pid>/maps, lsof, etc. Generate a debug-oriented synthetic 'filename' based on the cdev, plus BDF, plus resource index.
This applies only to BAR mappings via the VFIO device fd, as explicitly-exported DMABUFs are named by userspace via the DMA_BUF_SET_NAME ioctl.
Signed-off-by: Matt Evans mattev@meta.com --- drivers/vfio/pci/vfio_pci_dmabuf.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c index a12432825e5e..04c7733fe712 100644 --- a/drivers/vfio/pci/vfio_pci_dmabuf.c +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -4,6 +4,7 @@ #include <linux/dma-buf-mapping.h> #include <linux/pci-p2pdma.h> #include <linux/dma-resv.h> +#include <uapi/linux/dma-buf.h>
#include "vfio_pci_priv.h"
@@ -467,6 +468,7 @@ int vfio_pci_core_mmap_prep_dmabuf(struct vfio_pci_core_device *vdev, { struct vfio_pci_dma_buf *priv; const unsigned int nr_ranges = 1; + char *bufname; int ret;
priv = kzalloc_obj(*priv); @@ -479,6 +481,20 @@ int vfio_pci_core_mmap_prep_dmabuf(struct vfio_pci_core_device *vdev, goto err_free_priv; }
+ bufname = kzalloc(DMA_BUF_NAME_LEN, GFP_KERNEL); + if (!bufname) { + ret = -ENOMEM; + goto err_free_phys; + } + + /* + * Maximum size of the friendly debug name is + * vfio1234567890:ffff:ff:3f.7-9 = 30, which fits within + * DMA_BUF_NAME_LEN. + */ + snprintf(bufname, DMA_BUF_NAME_LEN, "%s:%s/%x", + dev_name(&vdev->vdev.device), pci_name(vdev->pdev), res_index); + /* * The mmap() request's vma->vm_offs might be non-zero, but * the DMABUF is created from _offset zero_ of the BAR. The @@ -501,7 +517,7 @@ int vfio_pci_core_mmap_prep_dmabuf(struct vfio_pci_core_device *vdev, priv->provider = pcim_p2pdma_provider(vdev->pdev, res_index); if (!priv->provider) { ret = -EINVAL; - goto err_free_phys; + goto err_free_name; }
priv->phys_vec[0].paddr = phys_start; @@ -509,7 +525,7 @@ int vfio_pci_core_mmap_prep_dmabuf(struct vfio_pci_core_device *vdev,
ret = vfio_pci_dmabuf_export(vdev, priv, O_CLOEXEC | O_RDWR); if (ret) - goto err_free_phys; + goto err_free_name;
/* * The VMA gets the DMABUF file so that other users can locate @@ -521,8 +537,15 @@ int vfio_pci_core_mmap_prep_dmabuf(struct vfio_pci_core_device *vdev, vma->vm_file = priv->dmabuf->file; vma->vm_private_data = priv;
+ spin_lock(&priv->dmabuf->name_lock); + kfree(priv->dmabuf->name); + priv->dmabuf->name = bufname; + spin_unlock(&priv->dmabuf->name_lock); + return 0;
+err_free_name: + kfree(bufname); err_free_phys: kfree(priv->phys_vec); err_free_priv: