Re: [PATCH 2/2] vfio: quieten dma-buf warning

[John Levon <john.levon@nutanix.com>]

On Thu, Apr 09, 2026 at 11:53:58AM +0200, Cédric Le Goater wrote:

> 1. quick one:
> 
>   Return -ENOTSUP and test the value in vfio_region_create_dma_buf().
>   It's cleaner than masking EINVAL IMO.

Scratch that, vfio can return this error too:

220         if (!vdev->pci_ops || !vdev->pci_ops->get_dmabuf_phys)
221                 return -EOPNOTSUPP;

> 2. cleaner one:
> 
>   Add a capability field to VFIODeviceIOOps to advertise supported
>   features:
>     #define VFIO_IO_CAP_DMA_BUF        (1 << 0)
>     #define VFIO_IO_CAP_MIGRATION      (1 << 1)
>     struct VFIODeviceIOOps {
>       uint64_t capabilities;  /* Bitmask of VFIO_IO_CAP_* */
>       ..
> and test vbasedev->io_ops->capabilities where needed.
> 
> How's that ? I can implement option 2.

I'd appreciate it, thanks, please let me know.

regards
john