xref: /qemu/hw/vfio/igd.c (revision 072e057ed90d6bbc4f01ac04e627e63f275f57f0)
1 /*
2  * IGD device quirks
3  *
4  * Copyright Red Hat, Inc. 2016
5  *
6  * Authors:
7  *  Alex Williamson <alex.williamson@redhat.com>
8  *
9  * This work is licensed under the terms of the GNU GPL, version 2.  See
10  * the COPYING file in the top-level directory.
11  */
12 
13 #include "qemu/osdep.h"
14 #include "qemu/units.h"
15 #include "qemu/error-report.h"
16 #include "qapi/error.h"
17 #include "qapi/qmp/qerror.h"
18 #include "hw/boards.h"
19 #include "hw/hw.h"
20 #include "hw/nvram/fw_cfg.h"
21 #include "pci.h"
22 #include "pci-quirks.h"
23 #include "trace.h"
24 
25 /*
26  * Intel IGD support
27  *
28  * Obviously IGD is not a discrete device, this is evidenced not only by it
29  * being integrated into the CPU, but by the various chipset and BIOS
30  * dependencies that it brings along with it.  Intel is trying to move away
31  * from this and Broadwell and newer devices can run in what Intel calls
32  * "Universal Pass-Through" mode, or UPT.  Theoretically in UPT mode, nothing
33  * more is required beyond assigning the IGD device to a VM.  There are
34  * however support limitations to this mode.  It only supports IGD as a
35  * secondary graphics device in the VM and it doesn't officially support any
36  * physical outputs.
37  *
38  * The code here attempts to enable what we'll call legacy mode assignment,
39  * IGD retains most of the capabilities we expect for it to have on bare
40  * metal.  To enable this mode, the IGD device must be assigned to the VM
41  * at PCI address 00:02.0, it must have a ROM, it very likely needs VGA
42  * support, we must have VM BIOS support for reserving and populating some
43  * of the required tables, and we need to tweak the chipset with revisions
44  * and IDs and an LPC/ISA bridge device.  The intention is to make all of
45  * this happen automatically by installing the device at the correct VM PCI
46  * bus address.  If any of the conditions are not met, we cross our fingers
47  * and hope the user knows better.
48  *
49  * NB - It is possible to enable physical outputs in UPT mode by supplying
50  * an OpRegion table.  We don't do this by default because the guest driver
51  * behaves differently if an OpRegion is provided and no monitor is attached
52  * vs no OpRegion and a monitor being attached or not.  Effectively, if a
53  * headless setup is desired, the OpRegion gets in the way of that.
54  */
55 
56 /*
57  * This presumes the device is already known to be an Intel VGA device, so we
58  * take liberties in which device ID bits match which generation.  This should
59  * not be taken as an indication that all the devices are supported, or even
60  * supportable, some of them don't even support VT-d.
61  * See linux:include/drm/i915_pciids.h for IDs.
62  */
63 static int igd_gen(VFIOPCIDevice *vdev)
64 {
65     /*
66      * Device IDs for Broxton/Apollo Lake are 0x0a84, 0x1a84, 0x1a85, 0x5a84
67      * and 0x5a85, match bit 11:1 here
68      * Prefix 0x0a is taken by Haswell, this rule should be matched first.
69      */
70     if ((vdev->device_id & 0xffe) == 0xa84) {
71         return 9;
72     }
73 
74     switch (vdev->device_id & 0xff00) {
75     case 0x0100:    /* SandyBridge, IvyBridge */
76         return 6;
77     case 0x0400:    /* Haswell */
78     case 0x0a00:    /* Haswell */
79     case 0x0c00:    /* Haswell */
80     case 0x0d00:    /* Haswell */
81     case 0x0f00:    /* Valleyview/Bay Trail */
82         return 7;
83     case 0x1600:    /* Broadwell */
84     case 0x2200:    /* Cherryview */
85         return 8;
86     case 0x1900:    /* Skylake */
87     case 0x3100:    /* Gemini Lake */
88     case 0x5900:    /* Kaby Lake */
89     case 0x3e00:    /* Coffee Lake */
90     case 0x9B00:    /* Comet Lake */
91         return 9;
92     case 0x8A00:    /* Ice Lake */
93     case 0x4500:    /* Elkhart Lake */
94     case 0x4E00:    /* Jasper Lake */
95         return 11;
96     case 0x9A00:    /* Tiger Lake */
97     case 0x4C00:    /* Rocket Lake */
98     case 0x4600:    /* Alder Lake */
99     case 0xA700:    /* Raptor Lake */
100         return 12;
101     }
102 
103     /*
104      * Unfortunately, Intel changes it's specification quite often. This makes
105      * it impossible to use a suitable default value for unknown devices.
106      */
107     return -1;
108 }
109 
110 #define IGD_ASLS 0xfc /* ASL Storage Register */
111 #define IGD_GMCH 0x50 /* Graphics Control Register */
112 #define IGD_BDSM 0x5c /* Base Data of Stolen Memory */
113 #define IGD_BDSM_GEN11 0xc0 /* Base Data of Stolen Memory of gen 11 and later */
114 
115 #define IGD_GMCH_GEN6_GMS_SHIFT     3       /* SNB_GMCH in i915 */
116 #define IGD_GMCH_GEN6_GMS_MASK      0x1f
117 #define IGD_GMCH_GEN8_GMS_SHIFT     8       /* BDW_GMCH in i915 */
118 #define IGD_GMCH_GEN8_GMS_MASK      0xff
119 
120 static uint64_t igd_stolen_memory_size(int gen, uint32_t gmch)
121 {
122     uint64_t gms;
123 
124     if (gen < 8) {
125         gms = (gmch >> IGD_GMCH_GEN6_GMS_SHIFT) & IGD_GMCH_GEN6_GMS_MASK;
126     } else {
127         gms = (gmch >> IGD_GMCH_GEN8_GMS_SHIFT) & IGD_GMCH_GEN8_GMS_MASK;
128     }
129 
130     if (gen < 9) {
131             return gms * 32 * MiB;
132     } else {
133         if (gms < 0xf0) {
134             return gms * 32 * MiB;
135         } else {
136             return (gms - 0xf0 + 1) * 4 * MiB;
137         }
138     }
139 
140     return 0;
141 }
142 
143 /*
144  * The OpRegion includes the Video BIOS Table, which seems important for
145  * telling the driver what sort of outputs it has.  Without this, the device
146  * may work in the guest, but we may not get output.  This also requires BIOS
147  * support to reserve and populate a section of guest memory sufficient for
148  * the table and to write the base address of that memory to the ASLS register
149  * of the IGD device.
150  */
151 static bool vfio_pci_igd_opregion_init(VFIOPCIDevice *vdev,
152                                        struct vfio_region_info *info,
153                                        Error **errp)
154 {
155     int ret;
156 
157     vdev->igd_opregion = g_malloc0(info->size);
158     ret = pread(vdev->vbasedev.fd, vdev->igd_opregion,
159                 info->size, info->offset);
160     if (ret != info->size) {
161         error_setg(errp, "failed to read IGD OpRegion");
162         g_free(vdev->igd_opregion);
163         vdev->igd_opregion = NULL;
164         return false;
165     }
166 
167     /*
168      * Provide fw_cfg with a copy of the OpRegion which the VM firmware is to
169      * allocate 32bit reserved memory for, copy these contents into, and write
170      * the reserved memory base address to the device ASLS register at 0xFC.
171      * Alignment of this reserved region seems flexible, but using a 4k page
172      * alignment seems to work well.  This interface assumes a single IGD
173      * device, which may be at VM address 00:02.0 in legacy mode or another
174      * address in UPT mode.
175      *
176      * NB, there may be future use cases discovered where the VM should have
177      * direct interaction with the host OpRegion, in which case the write to
178      * the ASLS register would trigger MemoryRegion setup to enable that.
179      */
180     fw_cfg_add_file(fw_cfg_find(), "etc/igd-opregion",
181                     vdev->igd_opregion, info->size);
182 
183     trace_vfio_pci_igd_opregion_enabled(vdev->vbasedev.name);
184 
185     pci_set_long(vdev->pdev.config + IGD_ASLS, 0);
186     pci_set_long(vdev->pdev.wmask + IGD_ASLS, ~0);
187     pci_set_long(vdev->emulated_config_bits + IGD_ASLS, ~0);
188 
189     return true;
190 }
191 
192 static bool vfio_pci_igd_setup_opregion(VFIOPCIDevice *vdev, Error **errp)
193 {
194     g_autofree struct vfio_region_info *opregion = NULL;
195     int ret;
196 
197     /* Hotplugging is not supported for opregion access */
198     if (vdev->pdev.qdev.hotplugged) {
199         error_setg(errp, "IGD OpRegion is not supported on hotplugged device");
200         return false;
201     }
202 
203     ret = vfio_device_get_region_info_type(&vdev->vbasedev,
204                     VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
205                     VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION, &opregion);
206     if (ret) {
207         error_setg_errno(errp, -ret,
208                          "Device does not supports IGD OpRegion feature");
209         return false;
210     }
211 
212     if (!vfio_pci_igd_opregion_init(vdev, opregion, errp)) {
213         return false;
214     }
215 
216     return true;
217 }
218 
219 /*
220  * The rather short list of registers that we copy from the host devices.
221  * The LPC/ISA bridge values are definitely needed to support the vBIOS, the
222  * host bridge values may or may not be needed depending on the guest OS.
223  * Since we're only munging revision and subsystem values on the host bridge,
224  * we don't require our own device.  The LPC/ISA bridge needs to be our very
225  * own though.
226  */
227 typedef struct {
228     uint8_t offset;
229     uint8_t len;
230 } IGDHostInfo;
231 
232 static const IGDHostInfo igd_host_bridge_infos[] = {
233     {PCI_REVISION_ID,         2},
234     {PCI_SUBSYSTEM_VENDOR_ID, 2},
235     {PCI_SUBSYSTEM_ID,        2},
236 };
237 
238 static const IGDHostInfo igd_lpc_bridge_infos[] = {
239     {PCI_VENDOR_ID,           2},
240     {PCI_DEVICE_ID,           2},
241     {PCI_REVISION_ID,         2},
242     {PCI_SUBSYSTEM_VENDOR_ID, 2},
243     {PCI_SUBSYSTEM_ID,        2},
244 };
245 
246 static int vfio_pci_igd_copy(VFIOPCIDevice *vdev, PCIDevice *pdev,
247                              struct vfio_region_info *info,
248                              const IGDHostInfo *list, int len)
249 {
250     int i, ret;
251 
252     for (i = 0; i < len; i++) {
253         ret = pread(vdev->vbasedev.fd, pdev->config + list[i].offset,
254                     list[i].len, info->offset + list[i].offset);
255         if (ret != list[i].len) {
256             error_report("IGD copy failed: %m");
257             return -errno;
258         }
259     }
260 
261     return 0;
262 }
263 
264 /*
265  * Stuff a few values into the host bridge.
266  */
267 static int vfio_pci_igd_host_init(VFIOPCIDevice *vdev,
268                                   struct vfio_region_info *info)
269 {
270     PCIBus *bus;
271     PCIDevice *host_bridge;
272     int ret;
273 
274     bus = pci_device_root_bus(&vdev->pdev);
275     host_bridge = pci_find_device(bus, 0, PCI_DEVFN(0, 0));
276 
277     if (!host_bridge) {
278         error_report("Can't find host bridge");
279         return -ENODEV;
280     }
281 
282     ret = vfio_pci_igd_copy(vdev, host_bridge, info, igd_host_bridge_infos,
283                             ARRAY_SIZE(igd_host_bridge_infos));
284     if (!ret) {
285         trace_vfio_pci_igd_host_bridge_enabled(vdev->vbasedev.name);
286     }
287 
288     return ret;
289 }
290 
291 /*
292  * IGD LPC/ISA bridge support code.  The vBIOS needs this, but we can't write
293  * arbitrary values into just any bridge, so we must create our own.  We try
294  * to handle if the user has created it for us, which they might want to do
295  * to enable multifunction so we don't occupy the whole PCI slot.
296  */
297 static void vfio_pci_igd_lpc_bridge_realize(PCIDevice *pdev, Error **errp)
298 {
299     if (pdev->devfn != PCI_DEVFN(0x1f, 0)) {
300         error_setg(errp, "VFIO dummy ISA/LPC bridge must have address 1f.0");
301     }
302 }
303 
304 static void vfio_pci_igd_lpc_bridge_class_init(ObjectClass *klass,
305                                                const void *data)
306 {
307     DeviceClass *dc = DEVICE_CLASS(klass);
308     PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
309 
310     set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
311     dc->desc = "VFIO dummy ISA/LPC bridge for IGD assignment";
312     dc->hotpluggable = false;
313     k->realize = vfio_pci_igd_lpc_bridge_realize;
314     k->class_id = PCI_CLASS_BRIDGE_ISA;
315 }
316 
317 static const TypeInfo vfio_pci_igd_lpc_bridge_info = {
318     .name = "vfio-pci-igd-lpc-bridge",
319     .parent = TYPE_PCI_DEVICE,
320     .class_init = vfio_pci_igd_lpc_bridge_class_init,
321     .interfaces = (const InterfaceInfo[]) {
322         { INTERFACE_CONVENTIONAL_PCI_DEVICE },
323         { },
324     },
325 };
326 
327 static void vfio_pci_igd_register_types(void)
328 {
329     type_register_static(&vfio_pci_igd_lpc_bridge_info);
330 }
331 
332 type_init(vfio_pci_igd_register_types)
333 
334 static int vfio_pci_igd_lpc_init(VFIOPCIDevice *vdev,
335                                  struct vfio_region_info *info)
336 {
337     PCIDevice *lpc_bridge;
338     int ret;
339 
340     lpc_bridge = pci_find_device(pci_device_root_bus(&vdev->pdev),
341                                  0, PCI_DEVFN(0x1f, 0));
342     if (!lpc_bridge) {
343         lpc_bridge = pci_create_simple(pci_device_root_bus(&vdev->pdev),
344                                  PCI_DEVFN(0x1f, 0), "vfio-pci-igd-lpc-bridge");
345     }
346 
347     ret = vfio_pci_igd_copy(vdev, lpc_bridge, info, igd_lpc_bridge_infos,
348                             ARRAY_SIZE(igd_lpc_bridge_infos));
349     if (!ret) {
350         trace_vfio_pci_igd_lpc_bridge_enabled(vdev->vbasedev.name);
351     }
352 
353     return ret;
354 }
355 
356 static bool vfio_pci_igd_setup_lpc_bridge(VFIOPCIDevice *vdev, Error **errp)
357 {
358     g_autofree struct vfio_region_info *host = NULL;
359     g_autofree struct vfio_region_info *lpc = NULL;
360     PCIDevice *lpc_bridge;
361     int ret;
362 
363     /*
364      * Copying IDs or creating new devices are not supported on hotplug
365      */
366     if (vdev->pdev.qdev.hotplugged) {
367         error_setg(errp, "IGD LPC is not supported on hotplugged device");
368         return false;
369     }
370 
371     /*
372      * We need to create an LPC/ISA bridge at PCI bus address 00:1f.0 that we
373      * can stuff host values into, so if there's already one there and it's not
374      * one we can hack on, this quirk is no-go.  Sorry Q35.
375      */
376     lpc_bridge = pci_find_device(pci_device_root_bus(&vdev->pdev),
377                                  0, PCI_DEVFN(0x1f, 0));
378     if (lpc_bridge && !object_dynamic_cast(OBJECT(lpc_bridge),
379                                            "vfio-pci-igd-lpc-bridge")) {
380         error_setg(errp,
381                    "Cannot create LPC bridge due to existing device at 1f.0");
382         return false;
383     }
384 
385     /*
386      * Check whether we have all the vfio device specific regions to
387      * support LPC quirk (added in Linux v4.6).
388      */
389     ret = vfio_device_get_region_info_type(&vdev->vbasedev,
390                         VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
391                         VFIO_REGION_SUBTYPE_INTEL_IGD_LPC_CFG, &lpc);
392     if (ret) {
393         error_setg(errp, "IGD LPC bridge access is not supported by kernel");
394         return false;
395     }
396 
397     ret = vfio_device_get_region_info_type(&vdev->vbasedev,
398                         VFIO_REGION_TYPE_PCI_VENDOR_TYPE | PCI_VENDOR_ID_INTEL,
399                         VFIO_REGION_SUBTYPE_INTEL_IGD_HOST_CFG, &host);
400     if (ret) {
401         error_setg(errp, "IGD host bridge access is not supported by kernel");
402         return false;
403     }
404 
405     /* Create/modify LPC bridge */
406     ret = vfio_pci_igd_lpc_init(vdev, lpc);
407     if (ret) {
408         error_setg(errp, "Failed to create/modify LPC bridge for IGD");
409         return false;
410     }
411 
412     /* Stuff some host values into the VM PCI host bridge */
413     ret = vfio_pci_igd_host_init(vdev, host);
414     if (ret) {
415         error_setg(errp, "Failed to modify host bridge for IGD");
416         return false;
417     }
418 
419     return true;
420 }
421 
422 #define IGD_GGC_MMIO_OFFSET     0x108040
423 #define IGD_BDSM_MMIO_OFFSET    0x1080C0
424 
425 void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr)
426 {
427     VFIOQuirk *ggc_quirk, *bdsm_quirk;
428     VFIOConfigMirrorQuirk *ggc_mirror, *bdsm_mirror;
429     int gen;
430 
431     /*
432      * This must be an Intel VGA device at address 00:02.0 for us to even
433      * consider enabling legacy mode. Some driver have dependencies on the PCI
434      * bus address.
435      */
436     if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
437         !vfio_is_vga(vdev) || nr != 0) {
438         return;
439     }
440 
441     /*
442      * Only on IGD devices of gen 11 and above, the BDSM register is mirrored
443      * into MMIO space and read from MMIO space by the Windows driver.
444      */
445     gen = igd_gen(vdev);
446     if (gen < 6) {
447         return;
448     }
449 
450     ggc_quirk = vfio_quirk_alloc(1);
451     ggc_mirror = ggc_quirk->data = g_malloc0(sizeof(*ggc_mirror));
452     ggc_mirror->mem = ggc_quirk->mem;
453     ggc_mirror->vdev = vdev;
454     ggc_mirror->bar = nr;
455     ggc_mirror->offset = IGD_GGC_MMIO_OFFSET;
456     ggc_mirror->config_offset = IGD_GMCH;
457 
458     memory_region_init_io(ggc_mirror->mem, OBJECT(vdev),
459                           &vfio_generic_mirror_quirk, ggc_mirror,
460                           "vfio-igd-ggc-quirk", 2);
461     memory_region_add_subregion_overlap(vdev->bars[nr].region.mem,
462                                         ggc_mirror->offset, ggc_mirror->mem,
463                                         1);
464 
465     QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, ggc_quirk, next);
466 
467     bdsm_quirk = vfio_quirk_alloc(1);
468     bdsm_mirror = bdsm_quirk->data = g_malloc0(sizeof(*bdsm_mirror));
469     bdsm_mirror->mem = bdsm_quirk->mem;
470     bdsm_mirror->vdev = vdev;
471     bdsm_mirror->bar = nr;
472     bdsm_mirror->offset = IGD_BDSM_MMIO_OFFSET;
473     bdsm_mirror->config_offset = (gen < 11) ? IGD_BDSM : IGD_BDSM_GEN11;
474 
475     memory_region_init_io(bdsm_mirror->mem, OBJECT(vdev),
476                           &vfio_generic_mirror_quirk, bdsm_mirror,
477                           "vfio-igd-bdsm-quirk", (gen < 11) ? 4 : 8);
478     memory_region_add_subregion_overlap(vdev->bars[nr].region.mem,
479                                         bdsm_mirror->offset, bdsm_mirror->mem,
480                                         1);
481 
482     QLIST_INSERT_HEAD(&vdev->bars[nr].quirks, bdsm_quirk, next);
483 }
484 
485 static bool vfio_pci_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
486 {
487     int ret, gen;
488     uint64_t gms_size;
489     uint64_t *bdsm_size;
490     uint32_t gmch;
491     bool legacy_mode_enabled = false;
492     Error *err = NULL;
493 
494     /*
495      * This must be an Intel VGA device at address 00:02.0 for us to even
496      * consider enabling legacy mode.  The vBIOS has dependencies on the
497      * PCI bus address.
498      */
499     if (!vfio_pci_is(vdev, PCI_VENDOR_ID_INTEL, PCI_ANY_ID) ||
500         !vfio_is_vga(vdev)) {
501         return true;
502     }
503 
504     /*
505      * IGD is not a standard, they like to change their specs often.  We
506      * only attempt to support back to SandBridge and we hope that newer
507      * devices maintain compatibility with generation 8.
508      */
509     gen = igd_gen(vdev);
510     if (gen == -1) {
511         error_report("IGD device %s is unsupported in legacy mode, "
512                      "try SandyBridge or newer", vdev->vbasedev.name);
513         return true;
514     }
515 
516     gmch = vfio_pci_read_config(&vdev->pdev, IGD_GMCH, 4);
517 
518     /*
519      * For backward compatibility, enable legacy mode when
520      * - Machine type is i440fx (pc_piix)
521      * - IGD device is at guest BDF 00:02.0
522      * - Not manually disabled by x-igd-legacy-mode=off
523      */
524     if ((vdev->igd_legacy_mode != ON_OFF_AUTO_OFF) &&
525         !strcmp(MACHINE_GET_CLASS(qdev_get_machine())->family, "pc_piix") &&
526         (&vdev->pdev == pci_find_device(pci_device_root_bus(&vdev->pdev),
527         0, PCI_DEVFN(0x2, 0)))) {
528         /*
529          * IGD legacy mode requires:
530          * - VBIOS in ROM BAR or file
531          * - VGA IO/MMIO ranges are claimed by IGD
532          * - OpRegion
533          * - Same LPC bridge and Host bridge VID/DID/SVID/SSID as host
534          */
535         g_autofree struct vfio_region_info *rom = NULL;
536 
537         legacy_mode_enabled = true;
538         info_report("IGD legacy mode enabled, "
539                     "use x-igd-legacy-mode=off to disable it if unwanted.");
540 
541         /*
542          * Most of what we're doing here is to enable the ROM to run, so if
543          * there's no ROM, there's no point in setting up this quirk.
544          * NB. We only seem to get BIOS ROMs, so UEFI VM would need CSM support.
545          */
546         ret = vfio_device_get_region_info(&vdev->vbasedev,
547                                           VFIO_PCI_ROM_REGION_INDEX, &rom);
548         if ((ret || !rom->size) && !vdev->pdev.romfile) {
549             error_setg(&err, "Device has no ROM");
550             goto error;
551         }
552 
553         /*
554          * If IGD VGA Disable is clear (expected) and VGA is not already
555          * enabled, try to enable it. Probably shouldn't be using legacy mode
556          * without VGA, but also no point in us enabling VGA if disabled in
557          * hardware.
558          */
559         if (!(gmch & 0x2) && !vdev->vga && !vfio_populate_vga(vdev, &err)) {
560             error_setg(&err, "Unable to enable VGA access");
561             goto error;
562         }
563 
564         /* Enable OpRegion and LPC bridge quirk */
565         vdev->features |= VFIO_FEATURE_ENABLE_IGD_OPREGION;
566         vdev->features |= VFIO_FEATURE_ENABLE_IGD_LPC;
567     } else if (vdev->igd_legacy_mode == ON_OFF_AUTO_ON) {
568         error_setg(&err,
569                    "Machine is not i440fx or assigned BDF is not 00:02.0");
570         goto error;
571     }
572 
573     /* Setup OpRegion access */
574     if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_OPREGION) &&
575         !vfio_pci_igd_setup_opregion(vdev, errp)) {
576         goto error;
577     }
578 
579     /* Setup LPC bridge / Host bridge PCI IDs */
580     if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_LPC) &&
581         !vfio_pci_igd_setup_lpc_bridge(vdev, errp)) {
582         goto error;
583      }
584 
585     /*
586      * Allow user to override dsm size using x-igd-gms option, in multiples of
587      * 32MiB. This option should only be used when the desired size cannot be
588      * set from DVMT Pre-Allocated option in host BIOS.
589      */
590     if (vdev->igd_gms) {
591         if (gen < 8) {
592             if (vdev->igd_gms <= 0x10) {
593                 gmch &= ~(IGD_GMCH_GEN6_GMS_MASK << IGD_GMCH_GEN6_GMS_SHIFT);
594                 gmch |= vdev->igd_gms << IGD_GMCH_GEN6_GMS_SHIFT;
595             } else {
596                 error_report(QERR_INVALID_PARAMETER_VALUE,
597                              "x-igd-gms", "0~0x10");
598             }
599         } else {
600             if (vdev->igd_gms <= 0x40) {
601                 gmch &= ~(IGD_GMCH_GEN8_GMS_MASK << IGD_GMCH_GEN8_GMS_SHIFT);
602                 gmch |= vdev->igd_gms << IGD_GMCH_GEN8_GMS_SHIFT;
603             } else {
604                 error_report(QERR_INVALID_PARAMETER_VALUE,
605                              "x-igd-gms", "0~0x40");
606             }
607         }
608     }
609 
610     gms_size = igd_stolen_memory_size(gen, gmch);
611 
612     /*
613      * Request reserved memory for stolen memory via fw_cfg.  VM firmware
614      * must allocate a 1MB aligned reserved memory region below 4GB with
615      * the requested size (in bytes) for use by the Intel PCI class VGA
616      * device at VM address 00:02.0.  The base address of this reserved
617      * memory region must be written to the device BDSM register at PCI
618      * config offset 0x5C.
619      */
620     bdsm_size = g_malloc(sizeof(*bdsm_size));
621     *bdsm_size = cpu_to_le64(gms_size);
622     fw_cfg_add_file(fw_cfg_find(), "etc/igd-bdsm-size",
623                     bdsm_size, sizeof(*bdsm_size));
624 
625     /* GMCH is read-only, emulated */
626     pci_set_long(vdev->pdev.config + IGD_GMCH, gmch);
627     pci_set_long(vdev->pdev.wmask + IGD_GMCH, 0);
628     pci_set_long(vdev->emulated_config_bits + IGD_GMCH, ~0);
629 
630     /* BDSM is read-write, emulated.  The BIOS needs to be able to write it */
631     if (gen < 11) {
632         pci_set_long(vdev->pdev.config + IGD_BDSM, 0);
633         pci_set_long(vdev->pdev.wmask + IGD_BDSM, ~0);
634         pci_set_long(vdev->emulated_config_bits + IGD_BDSM, ~0);
635     } else {
636         pci_set_quad(vdev->pdev.config + IGD_BDSM_GEN11, 0);
637         pci_set_quad(vdev->pdev.wmask + IGD_BDSM_GEN11, ~0);
638         pci_set_quad(vdev->emulated_config_bits + IGD_BDSM_GEN11, ~0);
639     }
640 
641     trace_vfio_pci_igd_bdsm_enabled(vdev->vbasedev.name, (gms_size / MiB));
642 
643     return true;
644 
645 error:
646     /*
647      * When legacy mode is implicity enabled, continue on error,
648      * to keep compatibility
649      */
650     if (legacy_mode_enabled && (vdev->igd_legacy_mode == ON_OFF_AUTO_AUTO)) {
651         error_report_err(err);
652         error_report("IGD legacy mode disabled");
653         return true;
654     }
655 
656     error_propagate(errp, err);
657     return false;
658 }
659 
660 /*
661  * KVMGT/GVT-g vGPU exposes an emulated OpRegion. So far, users have to specify
662  * x-igd-opregion=on to enable the access.
663  * TODO: Check VID/DID and enable opregion access automatically
664  */
665 static bool vfio_pci_kvmgt_config_quirk(VFIOPCIDevice *vdev, Error **errp)
666 {
667     if ((vdev->features & VFIO_FEATURE_ENABLE_IGD_OPREGION) &&
668         !vfio_pci_igd_setup_opregion(vdev, errp)) {
669         return false;
670     }
671 
672     return true;
673 }
674 
675 bool vfio_probe_igd_config_quirk(VFIOPCIDevice *vdev, Error **errp)
676 {
677     /* KVMGT/GVT-g vGPU is exposed as mdev */
678     if (vdev->vbasedev.mdev) {
679         return vfio_pci_kvmgt_config_quirk(vdev, errp);
680     }
681 
682     return vfio_pci_igd_config_quirk(vdev, errp);
683 }
684