1 files changed, 229 insertions, 300 deletions
diff --git a/hw/vfio/igd.c b/hw/vfio/igd.c
index b1a237e..265fffc 100644
--- a/hw/vfio/igd.c
+++ b/hw/vfio/igd.c
@@ -15,6 +15,7 @@
 #include "qemu/error-report.h"
 #include "qapi/error.h"
 #include "qapi/qmp/qerror.h"
+#include "hw/boards.h"
 #include "hw/hw.h"
 #include "hw/nvram/fw_cfg.h"
 #include "pci.h"
@@ -106,40 +107,15 @@ static int igd_gen(VFIOPCIDevice *vdev)
     return -1;
 }
 
-typedef struct VFIOIGDQuirk {
-    struct VFIOPCIDevice *vdev;
-    uint32_t index;
-    uint64_t bdsm;
-} VFIOIGDQuirk;
-
+#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 */
 
 #define IGD_GMCH_GEN6_GMS_SHIFT     3       /* SNB_GMCH in i915 */
 #define IGD_GMCH_GEN6_GMS_MASK      0x1f
-#define IGD_GMCH_GEN6_GGMS_SHIFT    8
-#define IGD_GMCH_GEN6_GGMS_MASK     0x3
 #define IGD_GMCH_GEN8_GMS_SHIFT     8       /* BDW_GMCH in i915 */
 #define IGD_GMCH_GEN8_GMS_MASK      0xff
-#define IGD_GMCH_GEN8_GGMS_SHIFT    6
-#define IGD_GMCH_GEN8_GGMS_MASK     0x3
-
-static uint64_t igd_gtt_memory_size(int gen, uint16_t gmch)
-{
-    uint64_t ggms;
-
-    if (gen < 8) {
-        ggms = (gmch >> IGD_GMCH_GEN6_GGMS_SHIFT) & IGD_GMCH_GEN6_GGMS_MASK;
-    } else {
-        ggms = (gmch >> IGD_GMCH_GEN8_GGMS_SHIFT) & IGD_GMCH_GEN8_GGMS_MASK;
-        if (ggms != 0) {
-            ggms = 1ULL << ggms;
-        }
-    }
-
-    return ggms * MiB;
-}
 
 static uint64_t igd_stolen_memory_size(int gen, uint32_t gmch)
 {
@@ -165,6 +141,82 @@ static uint64_t igd_stolen_memory_size(int gen, uint32_t gmch)
 }
 
 /*
+ * 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;
+}
+
+static 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
  * host bridge values may or may not be needed depending on the guest OS.
@@ -300,129 +352,72 @@ static int vfio_pci_igd_lpc_init(VFIOPCIDevice *vdev,
     return ret;
 }
 
-/*
- * IGD Gen8 and newer support up to 8MB for the GTT and use a 64bit PTE
- * entry, older IGDs use 2MB and 32bit.  Each PTE maps a 4k page.  Therefore
- * we either have 2M/4k * 4 = 2k or 8M/4k * 8 = 16k as the maximum iobar index
- * for programming the GTT.
- *
- * See linux:include/drm/i915_drm.h for shift and mask values.
- */
-static int vfio_igd_gtt_max(VFIOPCIDevice *vdev)
-{
-    uint32_t gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, sizeof(gmch));
-    int gen = igd_gen(vdev);
-    uint64_t ggms_size = igd_gtt_memory_size(gen, gmch);
-
-    return (ggms_size / (4 * KiB)) * (gen < 8 ? 4 : 8);
-}
-
-/*
- * The IGD ROM will make use of stolen memory (GGMS) for support of VESA modes.
- * Somehow the host stolen memory range is used for this, but how the ROM gets
- * it is a mystery, perhaps it's hardcoded into the ROM.  Thankfully though, it
- * reprograms the GTT through the IOBAR where we can trap it and transpose the
- * programming to the VM allocated buffer.  That buffer gets reserved by the VM
- * firmware via the fw_cfg entry added below.  Here we're just monitoring the
- * IOBAR address and data registers to detect a write sequence targeting the
- * GTTADR.  This code is developed by observed behavior and doesn't have a
- * direct spec reference, unfortunately.
- */
-static uint64_t vfio_igd_quirk_data_read(void *opaque,
-                                         hwaddr addr, unsigned size)
-{
-    VFIOIGDQuirk *igd = opaque;
-    VFIOPCIDevice *vdev = igd->vdev;
-
-    igd->index = ~0;
-
-    return vfio_region_read(&vdev->bars[4].region, addr + 4, size);
-}
-
-static void vfio_igd_quirk_data_write(void *opaque, hwaddr addr,
-                                      uint64_t data, unsigned size)
+static bool vfio_pci_igd_setup_lpc_bridge(VFIOPCIDevice *vdev, Error **errp)
 {
-    VFIOIGDQuirk *igd = opaque;
-    VFIOPCIDevice *vdev = igd->vdev;
-    uint64_t val = data;
-    int gen = igd_gen(vdev);
+    g_autofree struct vfio_region_info *host = NULL;
+    g_autofree struct vfio_region_info *lpc = NULL;
+    PCIDevice *lpc_bridge;
+    int ret;
 
     /*
-     * Programming the GGMS starts at index 0x1 and uses every 4th index (ie.
-     * 0x1, 0x5, 0x9, 0xd,...).  For pre-Gen8 each 4-byte write is a whole PTE
-     * entry, with 0th bit enable set.  For Gen8 and up, PTEs are 64bit, so
-     * entries 0x5 & 0xd are the high dword, in our case zero.  Each PTE points
-     * to a 4k page, which we translate to a page from the VM allocated region,
-     * pointed to by the BDSM register.  If this is not set, we fail.
-     *
-     * We trap writes to the full configured GTT size, but we typically only
-     * see the vBIOS writing up to (nearly) the 1MB barrier.  In fact it often
-     * seems to miss the last entry for an even 1MB GTT.  Doing a gratuitous
-     * write of that last entry does work, but is hopefully unnecessary since
-     * we clear the previous GTT on initialization.
+     * Copying IDs or creating new devices are not supported on hotplug
      */
-    if ((igd->index % 4 == 1) && igd->index < vfio_igd_gtt_max(vdev)) {
-        if (gen < 8 || (igd->index % 8 == 1)) {
-            uint64_t base;
-
-            if (gen < 11) {
-                base = pci_get_long(vdev->pdev.config + IGD_BDSM);
-            } else {
-                base = pci_get_quad(vdev->pdev.config + IGD_BDSM_GEN11);
-            }
-            if (!base) {
-                hw_error("vfio-igd: Guest attempted to program IGD GTT before "
-                         "BIOS reserved stolen memory.  Unsupported BIOS?");
-            }
-
-            val = data - igd->bdsm + base;
-        } else {
-            val = 0; /* upper 32bits of pte, we only enable below 4G PTEs */
-        }
-
-        trace_vfio_pci_igd_bar4_write(vdev->vbasedev.name,
-                                      igd->index, data, val);
+    if (vdev->pdev.qdev.hotplugged) {
+        error_setg(errp, "IGD LPC is not supported on hotplugged device");
+        return false;
     }
 
-    vfio_region_write(&vdev->bars[4].region, addr + 4, val, size);
-
-    igd->index = ~0;
-}
-
-static const MemoryRegionOps vfio_igd_data_quirk = {
-    .read = vfio_igd_quirk_data_read,
-    .write = vfio_igd_quirk_data_write,
-    .endianness = DEVICE_LITTLE_ENDIAN,
-};
-
-static uint64_t vfio_igd_quirk_index_read(void *opaque,
-                                          hwaddr addr, unsigned size)
-{
-    VFIOIGDQuirk *igd = opaque;
-    VFIOPCIDevice *vdev = igd->vdev;
+    /*
+     * We need to create an LPC/ISA bridge at PCI bus address 00:1f.0 that we
+     * can stuff host values into, so if there's already one there and it's not
+     * one we can hack on, this quirk is no-go.  Sorry Q35.
+     */
+    lpc_bridge = pci_find_device(pci_device_root_bus(&vdev->pdev),
+                                 0, PCI_DEVFN(0x1f, 0));
+    if (lpc_bridge && !object_dynamic_cast(OBJECT(lpc_bridge),
+                                           "vfio-pci-igd-lpc-bridge")) {
+        error_setg(errp,
+                   "Cannot create LPC bridge due to existing device at 1f.0");
+        return false;
+    }
 
-    igd->index = ~0;
+    /*
+     * Check whether we have all the vfio device specific regions to
+     * support LPC quirk (added in Linux v4.6).
+     */
+    ret = vfio_get_dev_region_info(&vdev->vbasedev,
+                        VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
+                        VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG, &lpc);
+    if (ret) {
+        error_setg(errp, "IGD LPC bridge access is not supported by kernel");
+        return false;
+    }
 
-    return vfio_region_read(&vdev->bars[4].region, addr, size);
-}
+    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);
+    if (ret) {
+        error_setg(errp, "IGD host bridge access is not supported by kernel");
+        return false;
+    }
 
-static void vfio_igd_quirk_index_write(void *opaque, hwaddr addr,
-                                       uint64_t data, unsigned size)
-{
-    VFIOIGDQuirk *igd = opaque;
-    VFIOPCIDevice *vdev = igd->vdev;
+    /* Create/modify LPC bridge */
+    ret = vfio_pci_igd_lpc_init(vdev, lpc);
+    if (ret) {
+        error_setg(errp, "Failed to create/modify LPC bridge for IGD");
+        return false;
+    }
 
-    igd->index = data;
+    /* Stuff some host values into the VM PCI host bridge */
+    ret = vfio_pci_igd_host_init(vdev, host);
+    if (ret) {
+        error_setg(errp, "Failed to modify host bridge for IGD");
+        return false;
+    }
 
-    vfio_region_write(&vdev->bars[4].region, addr, data, size);
+    return true;
 }
 
-static const MemoryRegionOps vfio_igd_index_quirk = {
-    .read = vfio_igd_quirk_index_read,
-    .write = vfio_igd_quirk_index_write,
-    .endianness = DEVICE_LITTLE_ENDIAN,
-};
-
 #define IGD_GGC_MMIO_OFFSET     0x108040
 #define IGD_BDSM_MMIO_OFFSET    0x1080C0
 
@@ -438,9 +433,7 @@ void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
      * bus address.
      */
     if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
-        !vfio_is_vga(vdev) || nr != 0 ||
-        &vdev->pdev != pci_find_device(pci_device_root_bus(&vdev->pdev),
-                                       0, PCI_DEVFN(0x2, 0))) {
+        !vfio_is_vga(vdev) || nr != 0) {
         return;
     }
 
@@ -488,20 +481,13 @@ void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
     QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, bdsm_quirk, next);
 }
 
-void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
+static bool vfio_pci_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
 {
-    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;
-    VFIOQuirk *quirk;
-    VFIOIGDQuirk *igd;
-    PCIDevice *lpc_bridge;
-    int i, ret, gen;
-    uint64_t ggms_size, gms_size;
+    int ret, gen;
+    uint64_t gms_size;
     uint64_t *bdsm_size;
     uint32_t gmch;
-    uint16_t cmd_orig, cmd;
+    bool legacy_mode_enabled = false;
     Error *err = NULL;
 
     /*
@@ -510,24 +496,8 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
      * PCI bus address.
      */
     if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
-        !vfio_is_vga(vdev) || nr != 4 ||
-        &vdev->pdev != pci_find_device(pci_device_root_bus(&vdev->pdev),
-                                       0, PCI_DEVFN(0x2, 0))) {
-        return;
-    }
-
-    /*
-     * We need to create an LPC/ISA bridge at PCI bus address 00:1f.0 that we
-     * can stuff host values into, so if there's already one there and it's not
-     * one we can hack on, legacy mode is no-go.  Sorry Q35.
-     */
-    lpc_bridge = pci_find_device(pci_device_root_bus(&vdev->pdev),
-                                 0, PCI_DEVFN(0x1f, 0));
-    if (lpc_bridge && !object_dynamic_cast(OBJECT(lpc_bridge),
-                                           "vfio-pci-igd-lpc-bridge")) {
-        error_report("IGD device %s cannot support legacy mode due to existing "
-                     "devices at address 1f.0", vdev->vbasedev.name);
-        return;
+        !vfio_is_vga(vdev)) {
+        return true;
     }
 
     /*
@@ -539,126 +509,77 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
     if (gen == -1) {
         error_report("IGD device %s is unsupported in legacy mode, "
                      "try SandyBridge or newer", vdev->vbasedev.name);
-        return;
-    }
-
-    /*
-     * Most of what we're doing here is to enable the ROM to run, so if
-     * there's no ROM, there's no point in setting up this quirk.
-     * NB. We only seem to get BIOS ROMs, so a UEFI VM would need CSM support.
-     */
-    ret = vfio_get_region_info(&vdev->vbasedev,
-                               VFIO_PCI_ROM_REGION_INDEX, &rom);
-    if ((ret || !rom->size) && !vdev->pdev.romfile) {
-        error_report("IGD device %s has no ROM, legacy mode disabled",
-                     vdev->vbasedev.name);
-        return;
-    }
-
-    /*
-     * Ignore the hotplug corner case, mark the ROM failed, we can't
-     * create the devices we need for legacy mode in the hotplug scenario.
-     */
-    if (vdev->pdev.qdev.hotplugged) {
-        error_report("IGD device %s hotplugged, ROM disabled, "
-                     "legacy mode disabled", vdev->vbasedev.name);
-        vdev->rom_read_failed = true;
-        return;
-    }
-
-    /*
-     * 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);
-    if (ret) {
-        error_report("IGD device %s does not support host bridge 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_LPC_CFG, &lpc);
-    if (ret) {
-        error_report("IGD device %s does not support LPC bridge access,"
-                     "legacy mode disabled", vdev->vbasedev.name);
-        return;
+        return true;
     }
 
     gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
 
     /*
-     * If IGD VGA Disable is clear (expected) and VGA is not already enabled,
-     * try to enable it.  Probably shouldn't be using legacy mode without VGA,
-     * but also no point in us enabling VGA if disabled in hardware.
+     * For backward compatibility, enable legacy mode when
+     * - Machine type is i440fx (pc_piix)
+     * - IGD device is at guest BDF 00:02.0
+     * - Not manually disabled by x-igd-legacy-mode=off
      */
-    if (!(gmch & 0x2) && !vdev->vga && !vfio_populate_vga(vdev, &err)) {
-        error_reportf_err(err, VFIO_MSG_PREFIX, vdev->vbasedev.name);
-        error_report("IGD device %s failed to enable VGA access, "
-                     "legacy mode disabled", vdev->vbasedev.name);
-        return;
-    }
+    if ((vdev->igd_legacy_mode != ON_OFF_AUTO_OFF) &&
+        !strcmp(MACHINE_GET_CLASS(qdev_get_machine())->family, "pc_piix") &&
+        (&vdev->pdev == pci_find_device(pci_device_root_bus(&vdev->pdev),
+        0, PCI_DEVFN(0x2, 0)))) {
+        /*
+         * IGD legacy mode requires:
+         * - VBIOS in ROM BAR or file
+         * - VGA IO/MMIO ranges are claimed by IGD
+         * - OpRegion
+         * - Same LPC bridge and Host bridge VID/DID/SVID/SSID as host
+         */
+        g_autofree struct vfio_region_info *rom = NULL;
+
+        legacy_mode_enabled = true;
+        info_report("IGD legacy mode enabled, "
+                    "use x-igd-legacy-mode=off to disable it if unwanted.");
+
+        /*
+         * Most of what we're doing here is to enable the ROM to run, so if
+         * there's no ROM, there's no point in setting up this quirk.
+         * NB. We only seem to get BIOS ROMs, so UEFI VM would need CSM support.
+         */
+        ret = vfio_get_region_info(&vdev->vbasedev,
+                                   VFIO_PCI_ROM_REGION_INDEX, &rom);
+        if ((ret || !rom->size) && !vdev->pdev.romfile) {
+            error_setg(&err, "Device has no ROM");
+            goto error;
+        }
 
-    /* Create our LPC/ISA bridge */
-    ret = vfio_pci_igd_lpc_init(vdev, lpc);
-    if (ret) {
-        error_report("IGD device %s failed to create LPC bridge, "
-                     "legacy mode disabled", vdev->vbasedev.name);
-        return;
-    }
+        /*
+         * If IGD VGA Disable is clear (expected) and VGA is not already
+         * enabled, try to enable it. Probably shouldn't be using legacy mode
+         * without VGA, but also no point in us enabling VGA if disabled in
+         * hardware.
+         */
+        if (!(gmch & 0x2) && !vdev->vga && !vfio_populate_vga(vdev, &err)) {
+            error_setg(&err, "Unable to enable VGA access");
+            goto error;
+        }
 
-    /* Stuff some host values into the VM PCI host bridge */
-    ret = vfio_pci_igd_host_init(vdev, host);
-    if (ret) {
-        error_report("IGD device %s failed to modify host bridge, "
-                     "legacy mode disabled", vdev->vbasedev.name);
-        return;
+        /* Enable OpRegion and LPC bridge quirk */
+        vdev->features |= VFIO_FEATURE_ENABLE_IGD_OPREGION;
+        vdev->features |= VFIO_FEATURE_ENABLE_IGD_LPC;
+    } else if (vdev->igd_legacy_mode == ON_OFF_AUTO_ON) {
+        error_setg(&err,
+                   "Machine is not i440fx or assigned BDF is not 00:02.0");
+        goto error;
     }
 
     /* 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;
+    if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_OPREGION) &&
+        !vfio_pci_igd_setup_opregion(vdev, errp)) {
+        goto error;
     }
 
-    /* Setup our quirk to munge GTT addresses to the VM allocated buffer */
-    quirk = vfio_quirk_alloc(2);
-    igd = quirk->data = g_malloc0(sizeof(*igd));
-    igd->vdev = vdev;
-    igd->index = ~0;
-    if (gen < 11) {
-        igd->bdsm = vfio_pci_read_config(&vdev->pdev, IGD_BDSM, 4);
-    } else {
-        igd->bdsm = vfio_pci_read_config(&vdev->pdev, IGD_BDSM_GEN11, 4);
-        igd->bdsm |=
-            (uint64_t)vfio_pci_read_config(&vdev->pdev, IGD_BDSM_GEN11 + 4, 4) << 32;
-    }
-    igd->bdsm &= ~((1 * MiB) - 1); /* 1MB aligned */
-
-    memory_region_init_io(&quirk->mem[0], OBJECT(vdev), &vfio_igd_index_quirk,
-                          igd, "vfio-igd-index-quirk", 4);
-    memory_region_add_subregion_overlap(vdev->bars[nr].region.mem,
-                                        0, &quirk->mem[0], 1);
-
-    memory_region_init_io(&quirk->mem[1], OBJECT(vdev), &vfio_igd_data_quirk,
-                          igd, "vfio-igd-data-quirk", 4);
-    memory_region_add_subregion_overlap(vdev->bars[nr].region.mem,
-                                        4, &quirk->mem[1], 1);
-
-    QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, quirk, next);
+    /* Setup LPC bridge / Host bridge PCI IDs */
+    if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_LPC) &&
+        !vfio_pci_igd_setup_lpc_bridge(vdev, errp)) {
+        goto error;
+     }
 
     /*
      * Allow user to override dsm size using x-igd-gms option, in multiples of
@@ -685,7 +606,6 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         }
     }
 
-    ggms_size = igd_gtt_memory_size(gen, gmch);
     gms_size = igd_stolen_memory_size(gen, gmch);
 
     /*
@@ -697,7 +617,7 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
      * config offset 0x5C.
      */
     bdsm_size = g_malloc(sizeof(*bdsm_size));
-    *bdsm_size = cpu_to_le64(ggms_size + gms_size);
+    *bdsm_size = cpu_to_le64(gms_size);
     fw_cfg_add_file(fw_cfg_find(), "etc/igd-bdsm-size",
                     bdsm_size, sizeof(*bdsm_size));
 
@@ -717,37 +637,46 @@ void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr)
         pci_set_quad(vdev->emulated_config_bits + IGD_BDSM_GEN11, ~0);
     }
 
+    trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name, (gms_size / MiB));
+
+    return true;
+
+error:
     /*
-     * This IOBAR gives us access to GTTADR, which allows us to write to
-     * the GTT itself.  So let's go ahead and write zero to all the GTT
-     * entries to avoid spurious DMA faults.  Be sure I/O access is enabled
-     * before talking to the device.
+     * When legacy mode is implicity enabled, continue on error,
+     * to keep compatibility
      */
-    if (pread(vdev->vbasedev.fd, &cmd_orig, sizeof(cmd_orig),
-              vdev->config_offset + PCI_COMMAND) != sizeof(cmd_orig)) {
-        error_report("IGD device %s - failed to read PCI command register",
-                     vdev->vbasedev.name);
+    if (legacy_mode_enabled && (vdev->igd_legacy_mode == ON_OFF_AUTO_AUTO)) {
+        error_report_err(err);
+        error_report("IGD legacy mode disabled");
+        return true;
     }
 
-    cmd = cmd_orig | PCI_COMMAND_IO;
+    error_propagate(errp, err);
+    return false;
+}
 
-    if (pwrite(vdev->vbasedev.fd, &cmd, sizeof(cmd),
-               vdev->config_offset + PCI_COMMAND) != sizeof(cmd)) {
-        error_report("IGD device %s - failed to write PCI command register",
-                     vdev->vbasedev.name);
+/*
+ * KVMGT/GVT-g vGPU exposes an emulated OpRegion. So far, users have to specify
+ * x-igd-opregion=on to enable the access.
+ * TODO: Check VID/DID and enable opregion access automatically
+ */
+static bool vfio_pci_kvmgt_config_quirk(VFIOPCIDevice *vdev, Error **errp)
+{
+    if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_OPREGION) &&
+        !vfio_pci_igd_setup_opregion(vdev, errp)) {
+        return false;
     }
 
-    for (i = 1; i < vfio_igd_gtt_max(vdev); i += 4) {
-        vfio_region_write(&vdev->bars[4].region, 0, i, 4);
-        vfio_region_write(&vdev->bars[4].region, 4, 0, 4);
-    }
+    return true;
+}
 
-    if (pwrite(vdev->vbasedev.fd, &cmd_orig, sizeof(cmd_orig),
-               vdev->config_offset + PCI_COMMAND) != sizeof(cmd_orig)) {
-        error_report("IGD device %s - failed to restore PCI command register",
-                     vdev->vbasedev.name);
+bool vfio_probe_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
+{
+    /* KVMGT/GVT-g vGPU is exposed as mdev */
+    if (vdev->vbasedev.mdev) {
+        return vfio_pci_kvmgt_config_quirk(vdev, errp);
     }
 
-    trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name,
-                                    (ggms_size + gms_size) / MiB);
+    return vfio_pci_igd_config_quirk(vdev, errp);
 }