On Mon, Mar 08, 2021 at 02:48:16PM -0700, Alex Williamson wrote:
> Add a new vfio_device_ops callback to allow the bus driver to
> translate a vma mapping of a vfio device fd to a pfn. Plumb through
> vfio-core. Implemented for vfio-pci.
>
> Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> drivers/vfio/pci/vfio_pci.c | 1 +
> drivers/vfio/vfio.c | 16 ++++++++++++++++
> include/linux/vfio.h | 3 +++
> 3 files changed, 20 insertions(+)
>
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index 415b5109da9b..585895970e9c 100644
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -1756,6 +1756,7 @@ static const struct vfio_device_ops vfio_pci_ops = {
> .mmap = vfio_pci_mmap,
> .request = vfio_pci_request,
> .match = vfio_pci_match,
> + .vma_to_pfn = vfio_pci_bar_vma_to_pfn,
> };
>
> static int vfio_pci_reflck_attach(struct vfio_pci_device *vdev);
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 3a3e85a0dc3e..c47895539a1a 100644
> +++ b/drivers/vfio/vfio.c
> @@ -944,6 +944,22 @@ struct vfio_device *vfio_device_get_from_vma(struct vm_area_struct *vma)
> }
> EXPORT_SYMBOL_GPL(vfio_device_get_from_vma);
>
> +int vfio_vma_to_pfn(struct vm_area_struct *vma, unsigned long *pfn)
> +{
> + struct vfio_device *device;
> +
> + if (!vma->vm_file || vma->vm_file->f_op != &vfio_device_fops)
> + return -EINVAL;
> +
> + device = vma->vm_file->private_data;
Since the caller has the vfio_device already I would pass in the
vfio_device here rather than look it up again.
If you are really worried about API mis-use then use a protective
assertion like this:
if (WARN_ON(vma->vm_file->private_data != device))
return -EINVAL;
Jason
