[PATCH v2] vfio/igd: Fix incorrect error propagation in vfio_pci_igd_opregion_detect()

[Tomita Moeko <tomitamoeko@gmail.com>]

In vfio_pci_igd_opregion_detect(), errp will be set when the device does
not have OpRegion or is hotplugged. This errp will be propagated to
pci_qdev_realize(), which interprets it as failure, causing unexpected
termination on devices without OpRegion like SR-IOV VFs or discrete
GPUs. Fix it by not setting errp in vfio_pci_igd_opregion_detect().

This patch also checks if the device has OpRegion before hotplug status
to prevent unwanted warning messages on non-IGD devices.

Fixes: c0273e77f2d7 ("vfio/igd: Detect IGD device by OpRegion")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2968
Reported-by: Edmund Raile <edmund.raile@protonmail.com>
Link: https://lore.kernel.org/qemu-devel/30044d14-17ec-46e3-b9c3-63d27a5bde27@gmail.com
Tested-by: Edmund Raile <edmund.raile@protonmail.com>
Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
---
v2:
* Add Tested-by from Edmund Raile. Thanks for the contribution.
* Rebased on vfio-next
* Fix typos.

 hw/vfio/igd.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index 5b6341c5bf..e7a9d1ffc1 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -187,23 +187,21 @@ static bool vfio_pci_igd_opregion_init(VFIOPCIDevice *vdev,
 }
 
 static bool vfio_pci_igd_opregion_detect(VFIOPCIDevice *vdev,
-                                         struct vfio_region_info **opregion,
-                                         Error **errp)
+                                         struct vfio_region_info **opregion)
 {
     int ret;
 
-    /* Hotplugging is not supported for opregion access */
-    if (vdev->pdev.qdev.hotplugged) {
-        error_setg(errp, "IGD OpRegion is not supported on hotplugged device");
-        return false;
-    }
-
     ret = vfio_device_get_region_info_type(&vdev->vbasedev,
                     VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
                     VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION, opregion);
     if (ret) {
-        error_setg_errno(errp, -ret,
-                         "Device does not support IGD OpRegion feature");
+        return false;
+    }
+
+    /* Hotplugging is not supported for opregion access */
+    if (vdev->pdev.qdev.hotplugged) {
+        warn_report("IGD device detected, but OpRegion is not supported "
+                    "on hotplugged device.");
         return false;
     }
 
@@ -524,7 +522,7 @@ static bool vfio_pci_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
     }
 
     /* IGD device always comes with OpRegion */
-    if (!vfio_pci_igd_opregion_detect(vdev, &opregion, errp)) {
+    if (!vfio_pci_igd_opregion_detect(vdev, &opregion)) {
         return true;
     }
     info_report("OpRegion detected on Intel display %x.", vdev->device_id);
@@ -695,7 +693,7 @@ static bool vfio_pci_kvmgt_config_quirk(VFIOPCIDevice *vdev, Error **errp)
         return true;
     }
 
-    if (!vfio_pci_igd_opregion_detect(vdev, &opregion, errp)) {
+    if (!vfio_pci_igd_opregion_detect(vdev, &opregion)) {
         /* Should never reach here, KVMGT always emulates OpRegion */
         return false;
     }
-- 
2.47.2