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

[Cédric Le Goater]

On 5/22/25 17:16, Tomita Moeko wrote:

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.ra...@protonmail.com>
Link: 
https://lore.kernel.org/qemu-devel/30044d14-17ec-46e3-b9c3-63d27a5bd...@gmail.com
Tested-by: Edmund Raile <edmund.ra...@protonmail.com>
Signed-off-by: Tomita Moeko <tomitamo...@gmail.com>
---
v2:
* Add Tested-by from Edmund Raile. Thanks for the contribution.
* Rebased on vfio-next
* Fix typos.

Edmund, Alex,

Could you please send a R-b ?

Thanks,

C.

  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;
      }