vfio: add region info cache

Instead of requesting region information on demand with
VFIO_DEVICE_GET_REGION_INFO, maintain a cache: this will become
necessary for performance for vfio-user, where this call becomes a
message over the control socket, so is of higher overhead than the
traditional path.

We will also need it to generalize region accesses, as that means we
can't use ->config_offset for configuration space accesses, but must
look up the region offset (if relevant) each time.

Originally-by: John Johnson <john.g.johnson@oracle.com>
Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Signed-off-by: John Levon <john.levon@nutanix.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250507152020.1254632-12-john.levon@nutanix.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
This commit is contained in:
John Levon 2025-05-07 16:20:16 +01:00 committed by Cédric Le Goater
parent 38bf025d0d
commit 95cdb02451
6 changed files with 31 additions and 18 deletions

View file

@ -83,6 +83,7 @@ typedef struct VFIODevice {
IOMMUFDBackend *iommufd;
VFIOIOASHwpt *hwpt;
QLIST_ENTRY(VFIODevice) hwpt_next;
struct vfio_region_info **reginfo;
} VFIODevice;
struct VFIODeviceOps {