ASLS register represents the base address of OpRegion, and it is
programmed with HPA. In IGD passthrough scenario, it needs to be
reprogrammed with GPA by guest firmware. To prevent guest accessing
wrong memory range, ASLS should always be emulated and cleared.

In GVT-g scenario, emulating ASLS is unnecessary as access is handled
by kvmgt backend [1].

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/i915/gvt/cfg_space.c?h=v6.14#n295

Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
---
 hw/vfio/igd.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index 01826acf10..36316e50ea 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -182,10 +182,6 @@ static bool vfio_pci_igd_opregion_init(VFIOPCIDevice *vdev,
 
     trace_vfio_pci_igd_opregion_enabled(vdev->vbasedev.name);
 
-    pci_set_long(vdev->pdev.config + IGD_ASLS, 0);
-    pci_set_long(vdev->pdev.wmask + IGD_ASLS, ~0);
-    pci_set_long(vdev->emulated_config_bits + IGD_ASLS, ~0);
-
     return true;
 }
 
@@ -583,7 +579,15 @@ static bool vfio_pci_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
     if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_LPC) &&
         !vfio_pci_igd_setup_lpc_bridge(vdev, errp)) {
         goto error;
-     }
+    }
+
+    /*
+     * ASLS (OpRegion address) is read-only, emulated
+     * It contains HPA, guest firmware need to reprogram it with GPA.
+     */
+    pci_set_long(vdev->pdev.config + IGD_ASLS, 0);
+    pci_set_long(vdev->pdev.wmask + IGD_ASLS, ~0);
+    pci_set_long(vdev->emulated_config_bits + IGD_ASLS, ~0);
 
     /*
      * Allow user to override dsm size using x-igd-gms option, in multiples of
-- 
2.47.2