virtio_gpu.c

   1 /*
   2  * Copyright 2017 The Chromium OS Authors. All rights reserved.
   3  * Use of this source code is governed by a BSD-style license that can be
   4  * found in the LICENSE file.
   5  */
   6
   7 #include <errno.h>
   8 #include <stdint.h>
   9 #include <stdio.h>
  10 #include <string.h>
  11 #include <sys/mman.h>
  12 #include <virtgpu_drm.h>
  13 #include <xf86drm.h>
  14
  15 #include "drv_priv.h"
  16 #include "helpers.h"
  17 #include "util.h"
  18 #include "virgl_hw.h"
  19
  20 #ifndef PAGE_SIZE
  21 #define PAGE_SIZE 0x1000
  22 #endif
  23 #define PIPE_TEXTURE_2D 2
  24
  25 #define MESA_LLVMPIPE_TILE_ORDER 6
  26 #define MESA_LLVMPIPE_TILE_SIZE (1 << MESA_LLVMPIPE_TILE_ORDER)
  27
  28 static const uint32_t render_target_formats[] = { DRM_FORMAT_ABGR8888, DRM_FORMAT_ARGB8888,
  29                                                   DRM_FORMAT_RGB565, DRM_FORMAT_XBGR8888,
  30                                                   DRM_FORMAT_XRGB8888 };
  31
  32 static const uint32_t dumb_texture_source_formats[] = { DRM_FORMAT_R8, DRM_FORMAT_YVU420,
  33                                                         DRM_FORMAT_NV12,
  34                                                         DRM_FORMAT_YVU420_ANDROID };
  35
  36 static const uint32_t texture_source_formats[] = { DRM_FORMAT_NV12, DRM_FORMAT_R8, DRM_FORMAT_RG88,
  37                                                    DRM_FORMAT_YVU420_ANDROID };
  38
  39 struct virtio_gpu_priv {
  40         int has_3d;
  41         int caps_is_v2;
  42         union virgl_caps caps;
  43 };
  44
  45 static uint32_t translate_format(uint32_t drm_fourcc)
  46 {
  47         switch (drm_fourcc) {
  48         case DRM_FORMAT_XRGB8888:
  49                 return VIRGL_FORMAT_B8G8R8X8_UNORM;
  50         case DRM_FORMAT_ARGB8888:
  51                 return VIRGL_FORMAT_B8G8R8A8_UNORM;
  52         case DRM_FORMAT_XBGR8888:
  53                 return VIRGL_FORMAT_R8G8B8X8_UNORM;
  54         case DRM_FORMAT_ABGR8888:
  55                 return VIRGL_FORMAT_R8G8B8A8_UNORM;
  56         case DRM_FORMAT_RGB565:
  57                 return VIRGL_FORMAT_B5G6R5_UNORM;
  58         case DRM_FORMAT_R8:
  59                 return VIRGL_FORMAT_R8_UNORM;
  60         case DRM_FORMAT_RG88:
  61                 return VIRGL_FORMAT_R8G8_UNORM;
  62         case DRM_FORMAT_NV12:
  63                 return VIRGL_FORMAT_NV12;
  64         case DRM_FORMAT_YVU420:
  65         case DRM_FORMAT_YVU420_ANDROID:
  66                 return VIRGL_FORMAT_YV12;
  67         default:
  68                 return 0;
  69         }
  70 }
  71
  72 static bool virtio_gpu_supports_format(struct virgl_supported_format_mask *supported,
  73                                        uint32_t drm_format)
  74 {
  75         uint32_t virgl_format = translate_format(drm_format);
  76         if (!virgl_format) {
  77                 return false;
  78         }
  79
  80         uint32_t bitmask_index = virgl_format / 32;
  81         uint32_t bit_index = virgl_format % 32;
  82         return supported->bitmask[bitmask_index] & (1 << bit_index);
  83 }
  84
  85 // Adds the given buffer combination to the list of supported buffer combinations if the
  86 // combination is supported by the virtio backend.
  87 static void virtio_gpu_add_combination(struct driver *drv, uint32_t drm_format,
  88                                        struct format_metadata *metadata, uint64_t use_flags)
  89 {
  90         struct virtio_gpu_priv *priv = (struct virtio_gpu_priv *)drv->priv;
  91
  92         if (priv->has_3d) {
  93                 if ((use_flags & BO_USE_RENDERING) &&
  94                     !virtio_gpu_supports_format(&priv->caps.v1.render, drm_format)) {
  95                         drv_log("Skipping unsupported render format: %d\n", drm_format);
  96                         return;
  97                 }
  98
  99                 if ((use_flags & BO_USE_TEXTURE) &&
 100                     !virtio_gpu_supports_format(&priv->caps.v1.sampler, drm_format)) {
 101                         drv_log("Skipping unsupported texture format: %d\n", drm_format);
 102                         return;
 103                 }
 104                 if ((use_flags & BO_USE_SCANOUT) && priv->caps_is_v2 &&
 105                     !virtio_gpu_supports_format(&priv->caps.v2.scanout, drm_format)) {
 106                         drv_log("Unsupported scanout format: %d\n", drm_format);
 107                         use_flags &= ~BO_USE_SCANOUT;
 108                 }
 109         }
 110
 111         drv_add_combination(drv, drm_format, metadata, use_flags);
 112 }
 113
 114 // Adds each given buffer combination to the list of supported buffer combinations if the
 115 // combination supported by the virtio backend.
 116 static void virtio_gpu_add_combinations(struct driver *drv, const uint32_t *drm_formats,
 117                                         uint32_t num_formats, struct format_metadata *metadata,
 118                                         uint64_t use_flags)
 119 {
 120         uint32_t i;
 121
 122         for (i = 0; i < num_formats; i++) {
 123                 virtio_gpu_add_combination(drv, drm_formats[i], metadata, use_flags);
 124         }
 125 }
 126
 127 static int virtio_dumb_bo_create(struct bo *bo, uint32_t width, uint32_t height, uint32_t format,
 128                                  uint64_t use_flags)
 129 {
 130         if (bo->meta.format != DRM_FORMAT_R8) {
 131                 width = ALIGN(width, MESA_LLVMPIPE_TILE_SIZE);
 132                 height = ALIGN(height, MESA_LLVMPIPE_TILE_SIZE);
 133         }
 134
 135         return drv_dumb_bo_create_ex(bo, width, height, format, use_flags, BO_QUIRK_DUMB32BPP);
 136 }
 137
 138 static inline void handle_flag(uint64_t *flag, uint64_t check_flag, uint32_t *bind,
 139                                uint32_t virgl_bind)
 140 {
 141         if ((*flag) & check_flag) {
 142                 (*flag) &= ~check_flag;
 143                 (*bind) |= virgl_bind;
 144         }
 145 }
 146
 147 static uint32_t use_flags_to_bind(uint64_t use_flags)
 148 {
 149         /* In crosvm, VIRGL_BIND_SHARED means minigbm will allocate, not virglrenderer. */
 150         uint32_t bind = VIRGL_BIND_SHARED;
 151
 152         handle_flag(&use_flags, BO_USE_TEXTURE, &bind, VIRGL_BIND_SAMPLER_VIEW);
 153         handle_flag(&use_flags, BO_USE_RENDERING, &bind, VIRGL_BIND_RENDER_TARGET);
 154         handle_flag(&use_flags, BO_USE_SCANOUT, &bind, VIRGL_BIND_SCANOUT);
 155         handle_flag(&use_flags, BO_USE_CURSOR, &bind, VIRGL_BIND_CURSOR);
 156         handle_flag(&use_flags, BO_USE_LINEAR, &bind, VIRGL_BIND_LINEAR);
 157
 158         handle_flag(&use_flags, BO_USE_SW_READ_OFTEN, &bind, VIRGL_BIND_LINEAR);
 159         handle_flag(&use_flags, BO_USE_SW_READ_RARELY, &bind, VIRGL_BIND_LINEAR);
 160         handle_flag(&use_flags, BO_USE_SW_WRITE_OFTEN, &bind, VIRGL_BIND_LINEAR);
 161         handle_flag(&use_flags, BO_USE_SW_WRITE_RARELY, &bind, VIRGL_BIND_LINEAR);
 162
 163         // All host drivers only support linear camera buffer formats. If
 164         // that changes, this will need to be modified.
 165         handle_flag(&use_flags, BO_USE_CAMERA_READ, &bind, VIRGL_BIND_LINEAR);
 166         handle_flag(&use_flags, BO_USE_CAMERA_WRITE, &bind, VIRGL_BIND_LINEAR);
 167
 168         if (use_flags) {
 169                 drv_log("Unhandled bo use flag: %llx\n", (unsigned long long)use_flags);
 170         }
 171
 172         return bind;
 173 }
 174
 175 static int virtio_virgl_bo_create(struct bo *bo, uint32_t width, uint32_t height, uint32_t format,
 176                                   uint64_t use_flags)
 177 {
 178         int ret;
 179         uint32_t stride;
 180         struct drm_virtgpu_resource_create res_create;
 181
 182         stride = drv_stride_from_format(format, width, 0);
 183         drv_bo_from_format(bo, stride, height, format);
 184
 185         /*
 186          * Setting the target is intended to ensure this resource gets bound as a 2D
 187          * texture in the host renderer's GL state. All of these resource properties are
 188          * sent unchanged by the kernel to the host, which in turn sends them unchanged to
 189          * virglrenderer. When virglrenderer makes a resource, it will convert the target
 190          * enum to the equivalent one in GL and then bind the resource to that target.
 191          */
 192         memset(&res_create, 0, sizeof(res_create));
 193
 194         res_create.target = PIPE_TEXTURE_2D;
 195         res_create.format = translate_format(format);
 196         res_create.bind = use_flags_to_bind(use_flags);
 197         res_create.width = width;
 198         res_create.height = height;
 199
 200         /* For virgl 3D */
 201         res_create.depth = 1;
 202         res_create.array_size = 1;
 203         res_create.last_level = 0;
 204         res_create.nr_samples = 0;
 205
 206         res_create.size = ALIGN(bo->meta.total_size, PAGE_SIZE); // PAGE_SIZE = 0x1000
 207         ret = drmIoctl(bo->drv->fd, DRM_IOCTL_VIRTGPU_RESOURCE_CREATE, &res_create);
 208         if (ret) {
 209                 drv_log("DRM_IOCTL_VIRTGPU_RESOURCE_CREATE failed with %s\n", strerror(errno));
 210                 return ret;
 211         }
 212
 213         for (uint32_t plane = 0; plane < bo->meta.num_planes; plane++)
 214                 bo->handles[plane].u32 = res_create.bo_handle;
 215
 216         return 0;
 217 }
 218
 219 static void *virtio_virgl_bo_map(struct bo *bo, struct vma *vma, size_t plane, uint32_t map_flags)
 220 {
 221         int ret;
 222         struct drm_virtgpu_map gem_map;
 223
 224         memset(&gem_map, 0, sizeof(gem_map));
 225         gem_map.handle = bo->handles[0].u32;
 226
 227         ret = drmIoctl(bo->drv->fd, DRM_IOCTL_VIRTGPU_MAP, &gem_map);
 228         if (ret) {
 229                 drv_log("DRM_IOCTL_VIRTGPU_MAP failed with %s\n", strerror(errno));
 230                 return MAP_FAILED;
 231         }
 232
 233         vma->length = bo->meta.total_size;
 234         return mmap(0, bo->meta.total_size, drv_get_prot(map_flags), MAP_SHARED, bo->drv->fd,
 235                     gem_map.offset);
 236 }
 237
 238 static int virtio_gpu_get_caps(struct driver *drv, union virgl_caps *caps, int *caps_is_v2)
 239 {
 240         int ret;
 241         struct drm_virtgpu_get_caps cap_args;
 242         struct drm_virtgpu_getparam param_args;
 243         uint32_t can_query_v2 = 0;
 244
 245         memset(&param_args, 0, sizeof(param_args));
 246         param_args.param = VIRTGPU_PARAM_CAPSET_QUERY_FIX;
 247         param_args.value = (uint64_t)(uintptr_t)&can_query_v2;
 248         ret = drmIoctl(drv->fd, DRM_IOCTL_VIRTGPU_GETPARAM, &param_args);
 249         if (ret) {
 250                 drv_log("DRM_IOCTL_VIRTGPU_GETPARAM failed with %s\n", strerror(errno));
 251         }
 252
 253         *caps_is_v2 = 0;
 254         memset(&cap_args, 0, sizeof(cap_args));
 255         cap_args.addr = (unsigned long long)caps;
 256         if (can_query_v2) {
 257                 *caps_is_v2 = 1;
 258                 cap_args.cap_set_id = 2;
 259                 cap_args.size = sizeof(union virgl_caps);
 260         } else {
 261                 cap_args.cap_set_id = 1;
 262                 cap_args.size = sizeof(struct virgl_caps_v1);
 263         }
 264
 265         ret = drmIoctl(drv->fd, DRM_IOCTL_VIRTGPU_GET_CAPS, &cap_args);
 266         if (ret) {
 267                 drv_log("DRM_IOCTL_VIRTGPU_GET_CAPS failed with %s\n", strerror(errno));
 268                 *caps_is_v2 = 0;
 269
 270                 // Fallback to v1
 271                 cap_args.cap_set_id = 1;
 272                 cap_args.size = sizeof(struct virgl_caps_v1);
 273
 274                 ret = drmIoctl(drv->fd, DRM_IOCTL_VIRTGPU_GET_CAPS, &cap_args);
 275                 if (ret) {
 276                         drv_log("DRM_IOCTL_VIRTGPU_GET_CAPS failed with %s\n", strerror(errno));
 277                 }
 278         }
 279
 280         return ret;
 281 }
 282
 283 static int virtio_gpu_init(struct driver *drv)
 284 {
 285         int ret;
 286         struct virtio_gpu_priv *priv;
 287         struct drm_virtgpu_getparam args;
 288
 289         priv = calloc(1, sizeof(*priv));
 290         drv->priv = priv;
 291
 292         memset(&args, 0, sizeof(args));
 293         args.param = VIRTGPU_PARAM_3D_FEATURES;
 294         args.value = (uint64_t)(uintptr_t)&priv->has_3d;
 295         ret = drmIoctl(drv->fd, DRM_IOCTL_VIRTGPU_GETPARAM, &args);
 296         if (ret) {
 297                 drv_log("virtio 3D acceleration is not available\n");
 298                 /* Be paranoid */
 299                 priv->has_3d = 0;
 300         }
 301
 302         if (priv->has_3d) {
 303                 virtio_gpu_get_caps(drv, &priv->caps, &priv->caps_is_v2);
 304
 305                 /* This doesn't mean host can scanout everything, it just means host
 306                  * hypervisor can show it. */
 307                 virtio_gpu_add_combinations(drv, render_target_formats,
 308                                             ARRAY_SIZE(render_target_formats), &LINEAR_METADATA,
 309                                             BO_USE_RENDER_MASK | BO_USE_SCANOUT);
 310                 virtio_gpu_add_combinations(drv, texture_source_formats,
 311                                             ARRAY_SIZE(texture_source_formats), &LINEAR_METADATA,
 312                                             BO_USE_TEXTURE_MASK);
 313         } else {
 314                 /* Virtio primary plane only allows this format. */
 315                 virtio_gpu_add_combination(drv, DRM_FORMAT_XRGB8888, &LINEAR_METADATA,
 316                                            BO_USE_RENDER_MASK | BO_USE_SCANOUT);
 317                 /* Virtio cursor plane only allows this format and Chrome cannot live without
 318                  * ARGB888 renderable format. */
 319                 virtio_gpu_add_combination(drv, DRM_FORMAT_ARGB8888, &LINEAR_METADATA,
 320                                            BO_USE_RENDER_MASK | BO_USE_CURSOR);
 321                 /* Android needs more, but they cannot be bound as scanouts anymore after
 322                  * "drm/virtio: fix DRM_FORMAT_* handling" */
 323                 virtio_gpu_add_combinations(drv, render_target_formats,
 324                                             ARRAY_SIZE(render_target_formats), &LINEAR_METADATA,
 325                                             BO_USE_RENDER_MASK);
 326                 virtio_gpu_add_combinations(drv, dumb_texture_source_formats,
 327                                             ARRAY_SIZE(dumb_texture_source_formats),
 328                                             &LINEAR_METADATA, BO_USE_TEXTURE_MASK);
 329                 virtio_gpu_add_combination(drv, DRM_FORMAT_NV12, &LINEAR_METADATA,
 330                                            BO_USE_SW_MASK | BO_USE_LINEAR);
 331         }
 332
 333         /* Android CTS tests require this. */
 334         virtio_gpu_add_combination(drv, DRM_FORMAT_BGR888, &LINEAR_METADATA, BO_USE_SW_MASK);
 335
 336         drv_modify_combination(drv, DRM_FORMAT_NV12, &LINEAR_METADATA,
 337                                BO_USE_CAMERA_READ | BO_USE_CAMERA_WRITE | BO_USE_HW_VIDEO_DECODER |
 338                                    BO_USE_HW_VIDEO_ENCODER);
 339         drv_modify_combination(drv, DRM_FORMAT_R8, &LINEAR_METADATA,
 340                                BO_USE_CAMERA_READ | BO_USE_CAMERA_WRITE);
 341
 342         return drv_modify_linear_combinations(drv);
 343 }
 344
 345 static void virtio_gpu_close(struct driver *drv)
 346 {
 347         free(drv->priv);
 348         drv->priv = NULL;
 349 }
 350
 351 static int virtio_gpu_bo_create(struct bo *bo, uint32_t width, uint32_t height, uint32_t format,
 352                                 uint64_t use_flags)
 353 {
 354         struct virtio_gpu_priv *priv = (struct virtio_gpu_priv *)bo->drv->priv;
 355         if (priv->has_3d)
 356                 return virtio_virgl_bo_create(bo, width, height, format, use_flags);
 357         else
 358                 return virtio_dumb_bo_create(bo, width, height, format, use_flags);
 359 }
 360
 361 static int virtio_gpu_bo_destroy(struct bo *bo)
 362 {
 363         struct virtio_gpu_priv *priv = (struct virtio_gpu_priv *)bo->drv->priv;
 364         if (priv->has_3d)
 365                 return drv_gem_bo_destroy(bo);
 366         else
 367                 return drv_dumb_bo_destroy(bo);
 368 }
 369
 370 static void *virtio_gpu_bo_map(struct bo *bo, struct vma *vma, size_t plane, uint32_t map_flags)
 371 {
 372         struct virtio_gpu_priv *priv = (struct virtio_gpu_priv *)bo->drv->priv;
 373         if (priv->has_3d)
 374                 return virtio_virgl_bo_map(bo, vma, plane, map_flags);
 375         else
 376                 return drv_dumb_bo_map(bo, vma, plane, map_flags);
 377 }
 378
 379 static int virtio_gpu_bo_invalidate(struct bo *bo, struct mapping *mapping)
 380 {
 381         int ret;
 382         struct drm_virtgpu_3d_transfer_from_host xfer;
 383         struct virtio_gpu_priv *priv = (struct virtio_gpu_priv *)bo->drv->priv;
 384         struct drm_virtgpu_3d_wait waitcmd;
 385
 386         if (!priv->has_3d)
 387                 return 0;
 388
 389         // Invalidate is only necessary if the host writes to the buffer.
 390         if ((bo->meta.use_flags & (BO_USE_RENDERING | BO_USE_CAMERA_WRITE |
 391                                    BO_USE_HW_VIDEO_ENCODER | BO_USE_HW_VIDEO_DECODER)) == 0)
 392                 return 0;
 393
 394         memset(&xfer, 0, sizeof(xfer));
 395         xfer.bo_handle = mapping->vma->handle;
 396         xfer.box.x = mapping->rect.x;
 397         xfer.box.y = mapping->rect.y;
 398         xfer.box.w = mapping->rect.width;
 399         xfer.box.h = mapping->rect.height;
 400         xfer.box.d = 1;
 401
 402         if ((bo->meta.use_flags & BO_USE_RENDERING) == 0) {
 403                 // Unfortunately, the kernel doesn't actually pass the guest layer_stride and
 404                 // guest stride to the host (compare virtio_gpu.h and virtgpu_drm.h). For gbm
 405                 // based resources, we can work around this by using the level field to pass
 406                 // the stride to virglrenderer's gbm transfer code. However, we need to avoid
 407                 // doing this for resources which don't rely on that transfer code, which is
 408                 // resources with the BO_USE_RENDERING flag set.
 409                 // TODO(b/145993887): Send also stride when the patches are landed
 410                 xfer.level = bo->meta.strides[0];
 411         }
 412
 413         ret = drmIoctl(bo->drv->fd, DRM_IOCTL_VIRTGPU_TRANSFER_FROM_HOST, &xfer);
 414         if (ret) {
 415                 drv_log("DRM_IOCTL_VIRTGPU_TRANSFER_FROM_HOST failed with %s\n", strerror(errno));
 416                 return -errno;
 417         }
 418
 419         // The transfer needs to complete before invalidate returns so that any host changes
 420         // are visible and to ensure the host doesn't overwrite subsequent guest changes.
 421         // TODO(b/136733358): Support returning fences from transfers
 422         memset(&waitcmd, 0, sizeof(waitcmd));
 423         waitcmd.handle = mapping->vma->handle;
 424         ret = drmIoctl(bo->drv->fd, DRM_IOCTL_VIRTGPU_WAIT, &waitcmd);
 425         if (ret) {
 426                 drv_log("DRM_IOCTL_VIRTGPU_WAIT failed with %s\n", strerror(errno));
 427                 return -errno;
 428         }
 429
 430         return 0;
 431 }
 432
 433 static int virtio_gpu_bo_flush(struct bo *bo, struct mapping *mapping)
 434 {
 435         int ret;
 436         struct drm_virtgpu_3d_transfer_to_host xfer;
 437         struct virtio_gpu_priv *priv = (struct virtio_gpu_priv *)bo->drv->priv;
 438         struct drm_virtgpu_3d_wait waitcmd;
 439
 440         if (!priv->has_3d)
 441                 return 0;
 442
 443         if (!(mapping->vma->map_flags & BO_MAP_WRITE))
 444                 return 0;
 445
 446         memset(&xfer, 0, sizeof(xfer));
 447         xfer.bo_handle = mapping->vma->handle;
 448         xfer.box.x = mapping->rect.x;
 449         xfer.box.y = mapping->rect.y;
 450         xfer.box.w = mapping->rect.width;
 451         xfer.box.h = mapping->rect.height;
 452         xfer.box.d = 1;
 453
 454         // Unfortunately, the kernel doesn't actually pass the guest layer_stride and
 455         // guest stride to the host (compare virtio_gpu.h and virtgpu_drm.h). We can use
 456         // the level to work around this.
 457         xfer.level = bo->meta.strides[0];
 458
 459         ret = drmIoctl(bo->drv->fd, DRM_IOCTL_VIRTGPU_TRANSFER_TO_HOST, &xfer);
 460         if (ret) {
 461                 drv_log("DRM_IOCTL_VIRTGPU_TRANSFER_TO_HOST failed with %s\n", strerror(errno));
 462                 return -errno;
 463         }
 464
 465         // If the buffer is only accessed by the host GPU, then the flush is ordered
 466         // with subsequent commands. However, if other host hardware can access the
 467         // buffer, we need to wait for the transfer to complete for consistency.
 468         // TODO(b/136733358): Support returning fences from transfers
 469         if (bo->meta.use_flags & BO_USE_NON_GPU_HW) {
 470                 memset(&waitcmd, 0, sizeof(waitcmd));
 471                 waitcmd.handle = mapping->vma->handle;
 472
 473                 ret = drmIoctl(bo->drv->fd, DRM_IOCTL_VIRTGPU_WAIT, &waitcmd);
 474                 if (ret) {
 475                         drv_log("DRM_IOCTL_VIRTGPU_WAIT failed with %s\n", strerror(errno));
 476                         return -errno;
 477                 }
 478         }
 479
 480         return 0;
 481 }
 482
 483 static uint32_t virtio_gpu_resolve_format(struct driver *drv, uint32_t format, uint64_t use_flags)
 484 {
 485         struct virtio_gpu_priv *priv = (struct virtio_gpu_priv *)drv->priv;
 486
 487         switch (format) {
 488         case DRM_FORMAT_FLEX_IMPLEMENTATION_DEFINED:
 489                 /* Camera subsystem requires NV12. */
 490                 if (use_flags & (BO_USE_CAMERA_READ | BO_USE_CAMERA_WRITE))
 491                         return DRM_FORMAT_NV12;
 492                 /*HACK: See b/28671744 */
 493                 return DRM_FORMAT_XBGR8888;
 494         case DRM_FORMAT_FLEX_YCbCr_420_888:
 495                 /*
 496                  * All of our host drivers prefer NV12 as their flexible media format.
 497                  * If that changes, this will need to be modified.
 498                  */
 499                 if (priv->has_3d)
 500                         return DRM_FORMAT_NV12;
 501                 else
 502                         return DRM_FORMAT_YVU420;
 503         default:
 504                 return format;
 505         }
 506 }
 507
 508 const struct backend backend_virtio_gpu = {
 509         .name = "virtio_gpu",
 510         .init = virtio_gpu_init,
 511         .close = virtio_gpu_close,
 512         .bo_create = virtio_gpu_bo_create,
 513         .bo_destroy = virtio_gpu_bo_destroy,
 514         .bo_import = drv_prime_bo_import,
 515         .bo_map = virtio_gpu_bo_map,
 516         .bo_unmap = drv_bo_munmap,
 517         .bo_invalidate = virtio_gpu_bo_invalidate,
 518         .bo_flush = virtio_gpu_bo_flush,
 519         .resolve_format = virtio_gpu_resolve_format,
 520 };