On Wed, 15 Jul 2026 18:47:29 +0100 Matt Evans <[email protected]> wrote:
> 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 <[email protected]> > Reviewed-by: Pranjal Shrivastava <[email protected]> > --- > drivers/vfio/pci/vfio_pci_dmabuf.c | 22 ++++++++++++++++++++-- > 1 file changed, 20 insertions(+), 2 deletions(-) > > diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c > b/drivers/vfio/pci/vfio_pci_dmabuf.c > index 46b3cf5dc94b..51606ff3cdc6 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> Is this required? It seems unused. > > #include "vfio_pci_priv.h" > > @@ -486,6 +487,7 @@ int vfio_pci_core_mmap_prep_dmabuf(struct > vfio_pci_core_device *vdev, > { > struct vfio_pci_dma_buf *priv; > unsigned long vma_pgoff = vma->vm_pgoff & (VFIO_PCI_OFFSET_MASK >> > PAGE_SHIFT); > + char *bufname; > int ret; > > priv = kzalloc_obj(*priv); > @@ -498,6 +500,15 @@ int vfio_pci_core_mmap_prep_dmabuf(struct > vfio_pci_core_device *vdev, > goto err_free_priv; > } > > + bufname = kasprintf(GFP_KERNEL, "%s:%s/%x", > + dev_name(&vdev->vdev.device), pci_name(vdev->pdev), > + res_index); > + > + if (!bufname) { > + ret = -ENOMEM; > + goto err_free_phys; > + } > + > /* > * The DMABUF begins from the mmap()'s BAR offset, i.e. the > * start of the VMA corresponds to byte 0 of the DMABUF and > @@ -516,7 +527,7 @@ 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 + ((u64)vma_pgoff << PAGE_SHIFT); > @@ -524,7 +535,7 @@ 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; > > /* > * Ownership of the DMABUF file transfers to the VMA so that > @@ -539,8 +550,15 @@ 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); This is simple, but shouldn't it really have a sanctioned, exported dmabuf helper rather than open coding this handling? Thanks, Alex > + > return 0; > > +err_free_name: > + kfree(bufname); > err_free_phys: > kfree(priv->phys_vec); > err_free_priv:
