A DMABUF exports access to BAR resources which need to be requested before the DMABUF is handed out. Usually the resources are requested when setting up the barmap when the VFIO device fd is mmap()ed, but there's no guarantee that happens before a DMABUF is created.
Set up the barmap (and so request resources) in the DMABUF-creation path.
Fixes: 5d74781ebc86c ("vfio/pci: Add dma-buf export support for MMIO regions") Signed-off-by: Matt Evans mattev@meta.com --- drivers/vfio/pci/vfio_pci_dmabuf.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
diff --git a/drivers/vfio/pci/vfio_pci_dmabuf.c b/drivers/vfio/pci/vfio_pci_dmabuf.c index 4be4a85005cb..46ab64fbeb19 100644 --- a/drivers/vfio/pci/vfio_pci_dmabuf.c +++ b/drivers/vfio/pci/vfio_pci_dmabuf.c @@ -258,6 +258,17 @@ int vfio_pci_core_feature_dma_buf(struct vfio_pci_core_device *vdev, u32 flags, goto err_free_priv; }
+ /* + * Just like the vfio_pci_core_mmap() path, we need to ensure + * PCI regions have been requested before returning DMABUFs + * that reference them. It's possible to create a DMABUF for + * a BAR without the BAR having already been mmap()ed. The + * barmap setup requests the regions for us: + */ + ret = vfio_pci_core_setup_barmap(vdev, get_dma_buf.region_index); + if (ret) + goto err_free_phys; + priv->vdev = vdev; priv->nr_ranges = get_dma_buf.nr_ranges; priv->size = length;