vfio: Find DMA available capability

The underlying host may be limiting the number of outstanding DMA
requests for type 1 IOMMU.  Add helper functions to check for the
DMA available capability and retrieve the current number of DMA
mappings allowed.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
[aw: vfio_get_info_dma_avail moved inside CONFIG_LINUX]
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2 files changed