[PULL 5/5] vfio/igd: Fix VGA regions are not exposed in legacy mode

["Cédric Le Goater" <clg@redhat.com>]

From: Tomita Moeko <tomitamoeko@gmail.com>

In commit a59d06305fff ("vfio/pci: Introduce x-pci-class-code option"),
pci_register_vga() has been moved ouside of vfio_populate_vga(). As a
result, IGD VGA ranges are no longer properly exposed to guest.

To fix this, call pci_register_vga() after vfio_populate_vga() legacy
mode. A wrapper function vfio_pci_config_register_vga() is introduced
to handle it.

Fixes: a59d06305fff ("vfio/pci: Introduce x-pci-class-code option")
Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250723160906.44941-3-tomitamoeko@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>
---
 hw/vfio/pci.h |  1 +
 hw/vfio/igd.c | 10 +++++++---
 hw/vfio/pci.c | 13 ++++++++++---
 3 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h
index bca289035aaebb6c4422b31e26bb1dd76ab5ae72..81465a8214a4008716806ae85c7f320f6b198bb2 100644
--- a/hw/vfio/pci.h
+++ b/hw/vfio/pci.h
@@ -253,6 +253,7 @@ extern const VMStateDescription vfio_display_vmstate;
 
 void vfio_pci_bars_exit(VFIOPCIDevice *vdev);
 bool vfio_pci_add_capabilities(VFIOPCIDevice *vdev, Error **errp);
+void vfio_pci_config_register_vga(VFIOPCIDevice *vdev);
 bool vfio_pci_config_setup(VFIOPCIDevice *vdev, Error **errp);
 bool vfio_pci_interrupt_setup(VFIOPCIDevice *vdev, Error **errp);
 void vfio_pci_intx_eoi(VFIODevice *vbasedev);
diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index 5b1ad1a8048b8753f524059810b1b17015704ac9..ee0767b0b89c085a5147369dd6fcbd3ff21f8927 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -574,9 +574,13 @@ static bool vfio_pci_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
          * If VGA is not already enabled, try to enable it. We shouldn't be
          * using legacy mode without VGA.
          */
-        if (!vdev->vga && !vfio_populate_vga(vdev, &err)) {
-            error_setg(&err, "Unable to enable VGA access");
-            goto error;
+        if (!vdev->vga) {
+            if (vfio_populate_vga(vdev, &err)) {
+                vfio_pci_config_register_vga(vdev);
+            } else {
+                error_setg(&err, "Unable to enable VGA access");
+                goto error;
+            }
         }
 
         /* Enable OpRegion and LPC bridge quirk */
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index f5bc5359eb8bdb8ddfa5f2b50d7387f2638bbeb4..4fa692c1a32bcfa4e4939e5fcb64f2bf19905b3b 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3162,6 +3162,15 @@ static void vfio_unregister_req_notifier(VFIOPCIDevice *vdev)
     vdev->req_enabled = false;
 }
 
+void vfio_pci_config_register_vga(VFIOPCIDevice *vdev)
+{
+    assert(vdev->vga != NULL);
+
+    pci_register_vga(&vdev->pdev, &vdev->vga->region[QEMU_PCI_VGA_MEM].mem,
+                     &vdev->vga->region[QEMU_PCI_VGA_IO_LO].mem,
+                     &vdev->vga->region[QEMU_PCI_VGA_IO_HI].mem);
+}
+
 bool vfio_pci_config_setup(VFIOPCIDevice *vdev, Error **errp)
 {
     PCIDevice *pdev = &vdev->pdev;
@@ -3283,9 +3292,7 @@ bool vfio_pci_config_setup(VFIOPCIDevice *vdev, Error **errp)
     vfio_bars_register(vdev);
 
     if (vdev->vga && vfio_is_vga(vdev)) {
-        pci_register_vga(&vdev->pdev, &vdev->vga->region[QEMU_PCI_VGA_MEM].mem,
-                         &vdev->vga->region[QEMU_PCI_VGA_IO_LO].mem,
-                         &vdev->vga->region[QEMU_PCI_VGA_IO_HI].mem);
+        vfio_pci_config_register_vga(vdev);
     }
 
     return true;
-- 
2.50.1