vfio: add strread/writeerror()

Add simple helpers to correctly report failures from read/write routines
using the return -errno style.

Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250507152020.1254632-7-john.levon@nutanix.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
1 file changed