vfio/igd: Consolidate OpRegion initialization into a single function

Both x-igd-opregion option and legacy mode require identical steps to
set up OpRegion for IGD devices. Consolidate these steps into a single
vfio_pci_igd_setup_opregion function.

The function call in pci.c is wrapped with ifdef temporarily to prevent
build error for non-x86 archs, it will be removed after we decouple it
from legacy mode.

Additionally, move vfio_pci_igd_opregion_init to igd.c to prevent it
from being compiled in non-x86 builds.

Signed-off-by: Tomita Moeko <tomitamoeko@gmail.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Corvin Köhne <c.koehne@beckhoff.com>
Link: https://lore.kernel.org/qemu-devel/20250306180131.32970-4-tomitamoeko@gmail.com
[ clg: Fixed spelling in vfio_pci_igd_setup_opregion() ]
Signed-off-by: Cédric Le Goater <clg@redhat.com>

hw/vfio/igd.c

@@ -106,6 +106,7 @@ static int igd_gen(VFIOPCIDevice *vdev)
     return -1;
 }
 
+#define IGD_ASLS 0xfc /* ASL Storage Register */
 #define IGD_GMCH 0x50 /* Graphics Control Register */
 #define IGD_BDSM 0x5c /* Base Data of Stolen Memory */
 #define IGD_BDSM_GEN11 0xc0 /* Base Data of Stolen Memory of gen 11 and later */
@@ -138,6 +139,82 @@ static uint64_t igd_stolen_memory_size(int gen, uint32_t gmch)
     return 0;
 }
 
+/*
+ * The OpRegion includes the Video BIOS Table, which seems important for
+ * telling the driver what sort of outputs it has.  Without this, the device
+ * may work in the guest, but we may not get output.  This also requires BIOS
+ * support to reserve and populate a section of guest memory sufficient for
+ * the table and to write the base address of that memory to the ASLS register
+ * of the IGD device.
+ */
+static bool vfio_pci_igd_opregion_init(VFIOPCIDevice *vdev,
+                                       struct vfio_region_info *info,
+                                       Error **errp)
+{
+    int ret;
+
+    vdev->igd_opregion = g_malloc0(info->size);
+    ret = pread(vdev->vbasedev.fd, vdev->igd_opregion,
+                info->size, info->offset);
+    if (ret != info->size) {
+        error_setg(errp, "failed to read IGD OpRegion");
+        g_free(vdev->igd_opregion);
+        vdev->igd_opregion = NULL;
+        return false;
+    }
+
+    /*
+     * Provide fw_cfg with a copy of the OpRegion which the VM firmware is to
+     * allocate 32bit reserved memory for, copy these contents into, and write
+     * the reserved memory base address to the device ASLS register at 0xFC.
+     * Alignment of this reserved region seems flexible, but using a 4k page
+     * alignment seems to work well.  This interface assumes a single IGD
+     * device, which may be at VM address 00:02.0 in legacy mode or another
+     * address in UPT mode.
+     *
+     * NB, there may be future use cases discovered where the VM should have
+     * direct interaction with the host OpRegion, in which case the write to
+     * the ASLS register would trigger MemoryRegion setup to enable that.
+     */
+    fw_cfg_add_file(fw_cfg_find(), "etc/igd-opregion",
+                    vdev->igd_opregion, info->size);
+
+    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;
+}
+
+bool vfio_pci_igd_setup_opregion(VFIOPCIDevice *vdev, Error **errp)
+{
+    g_autofree struct vfio_region_info *opregion = NULL;
+    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_get_dev_region_info(&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 supports IGD OpRegion feature");
+        return false;
+    }
+
+    if (!vfio_pci_igd_opregion_init(vdev, opregion, errp)) {
+        return false;
+    }
+
+    return true;
+}
+
 /*
  * The rather short list of registers that we copy from the host devices.
  * The LPC/ISA bridge values are definitely needed to support the vBIOS, the
@@ -342,7 +419,6 @@ void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
 void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
 {
     g_autofree struct vfio_region_info *rom = NULL;
-    g_autofree struct vfio_region_info *opregion = NULL;
     g_autofree struct vfio_region_info *host = NULL;
     g_autofree struct vfio_region_info *lpc = NULL;
     PCIDevice *lpc_bridge;
@@ -418,15 +494,6 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
      * Check whether we have all the vfio device specific regions to
      * support legacy mode (added in Linux v4.6).  If not, bail.
      */
-    ret = vfio_get_dev_region_info(&vdev->vbasedev,
-                        VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
-                        VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION, &opregion);
-    if (ret) {
-        error_report("IGD device %s does not support OpRegion access,"
-                     "legacy mode disabled", vdev->vbasedev.name);
-        return;
-    }
-
     ret = vfio_get_dev_region_info(&vdev->vbasedev,
                         VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
                         VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG, &host);
@@ -459,6 +526,13 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         return;
     }
 
+    /* Setup OpRegion access */
+    if (!vfio_pci_igd_setup_opregion(vdev, &err)) {
+        error_append_hint(&err, "IGD legacy mode disabled\n");
+        error_report_err(err);
+        return;
+    }
+
     /* Create our LPC/ISA bridge */
     ret = vfio_pci_igd_lpc_init(vdev, lpc);
     if (ret) {
@@ -475,13 +549,6 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         return;
     }
 
-    /* Setup OpRegion access */
-    if (!vfio_pci_igd_opregion_init(vdev, opregion, &err)) {
-        error_append_hint(&err, "IGD legacy mode disabled\n");
-        error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
-        return;
-    }
-
     /*
      * Allow user to override dsm size using x-igd-gms option, in multiples of
      * 32MiB. This option should only be used when the desired size cannot be

hw/vfio/pci-quirks.c

@@ -1114,56 +1114,6 @@ static void vfio_probe_rtl8168_bar2_quirk(VFIOPCIDevice *vdev, int nr)
     trace_vfio_quirk_rtl8168_probe(vdev->vbasedev.name);
 }
 
-#define IGD_ASLS 0xfc /* ASL Storage Register */
-
-/*
- * The OpRegion includes the Video BIOS Table, which seems important for
- * telling the driver what sort of outputs it has.  Without this, the device
- * may work in the guest, but we may not get output.  This also requires BIOS
- * support to reserve and populate a section of guest memory sufficient for
- * the table and to write the base address of that memory to the ASLS register
- * of the IGD device.
- */
-bool vfio_pci_igd_opregion_init(VFIOPCIDevice *vdev,
-                                struct vfio_region_info *info, Error **errp)
-{
-    int ret;
-
-    vdev->igd_opregion = g_malloc0(info->size);
-    ret = pread(vdev->vbasedev.fd, vdev->igd_opregion,
-                info->size, info->offset);
-    if (ret != info->size) {
-        error_setg(errp, "failed to read IGD OpRegion");
-        g_free(vdev->igd_opregion);
-        vdev->igd_opregion = NULL;
-        return false;
-    }
-
-    /*
-     * Provide fw_cfg with a copy of the OpRegion which the VM firmware is to
-     * allocate 32bit reserved memory for, copy these contents into, and write
-     * the reserved memory base address to the device ASLS register at 0xFC.
-     * Alignment of this reserved region seems flexible, but using a 4k page
-     * alignment seems to work well.  This interface assumes a single IGD
-     * device, which may be at VM address 00:02.0 in legacy mode or another
-     * address in UPT mode.
-     *
-     * NB, there may be future use cases discovered where the VM should have
-     * direct interaction with the host OpRegion, in which case the write to
-     * the ASLS register would trigger MemoryRegion setup to enable that.
-     */
-    fw_cfg_add_file(fw_cfg_find(), "etc/igd-opregion",
-                    vdev->igd_opregion, info->size);
-
-    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;
-}
-
 /*
  * Common quirk probe entry points.
  */

hw/vfio/pci.c

@@ -3136,30 +3136,14 @@ static void vfio_realize(PCIDevice *pdev, Error **errp)
         vfio_bar_quirk_setup(vdev, i);
     }
 
+#ifdef CONFIG_VFIO_IGD
     if (!vdev->igd_opregion &&
         vdev->features & VFIO_FEATURE_ENABLE_IGD_OPREGION) {
-        g_autofree struct vfio_region_info *opregion = NULL;
+        if (!vfio_pci_igd_setup_opregion(vdev, errp)) {
-
-        if (vdev->pdev.qdev.hotplugged) {
-            error_setg(errp,
-                       "cannot support IGD OpRegion feature on hotplugged "
-                       "device");
-            goto out_unset_idev;
-        }
-
-        ret = vfio_get_dev_region_info(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,
-                             "does not support requested IGD OpRegion feature");
-            goto out_unset_idev;
-        }
-
-        if (!vfio_pci_igd_opregion_init(vdev, opregion, errp)) {
             goto out_unset_idev;
         }
     }
+#endif
 
     /* QEMU emulates all of MSI & MSIX */
     if (pdev->cap_present & QEMU_PCI_CAP_MSIX) {

hw/vfio/pci.h

@@ -227,9 +227,7 @@ int vfio_pci_get_pci_hot_reset_info(VFIOPCIDevice *vdev,
 
 bool vfio_populate_vga(VFIOPCIDevice *vdev, Error **errp);
 
-bool vfio_pci_igd_opregion_init(VFIOPCIDevice *vdev,
+bool vfio_pci_igd_setup_opregion(VFIOPCIDevice *vdev, Error **errp);
-                                struct vfio_region_info *info,
-                                Error **errp);
 
 void vfio_display_reset(VFIOPCIDevice *vdev);
 bool vfio_display_probe(VFIOPCIDevice *vdev, Error **errp);