vfio/igd: Check OpRegion support on GVT-g mdev

The Intel GVT-g backend `kvmgt` always emulates OpRegion for vGPU,
make sure the OpRegion is present for enabling access to it
automatically later.

Also, hotplugging GVT-g vGPU is now always disallowed regardless of
OpRegion to prevent potential issues. Intel has never claimed support
for GVT-g hotplugging.

Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
Reviewed-by: Corvin Köhne <c.koehne@beckhoff.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250505170305.23622-6-tomitamoeko@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index f5dd4750282920a71c52ca59f9ca42899d895c1e..9dec32818c91f2021f6dc0c4bbe1fc0682df1a55 100644 (file)
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -685,9 +685,13 @@ static bool vfio_pci_kvmgt_config_quirk(VFIOPCIDevice *vdev, Error **errp)
         return true;
     }
 
+    if (!vfio_pci_igd_opregion_detect(vdev, &opregion, errp)) {
+        /* Should never reach here, KVMGT always emulates OpRegion */
+        return false;
+    }
+
     if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_OPREGION) &&
-        (!vfio_pci_igd_opregion_detect(vdev, &opregion, errp) ||
-         !vfio_pci_igd_opregion_init(vdev, opregion, errp))) {
+        !vfio_pci_igd_opregion_init(vdev, opregion, errp)) {
         return false;
     }