ttm: add prime sharing support to TTM (v2)

This adds the ability for ttm common code to take an SG table
and use it as the backing for a slave TTM object.

The drivers can then populate their GTT tables using the SG object.

v2: make sure to setup VM for sg bos as well.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

6 files changed, 28 insertions, 6 deletions

diff --git a/drivers/gpu/drm/nouveau/nouveau_bo.c b/drivers/gpu/drm/nouveau/nouveau_bo.c
index 12ce044f12f5..81599d6e636b 100644
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c
+++ b/drivers/gpu/drm/nouveau/nouveau_bo.c
@@ -121,7 +121,7 @@ nouveau_bo_new(struct drm_device *dev, int size, int align,
 
         ret = ttm_bo_init(&dev_priv->ttm.bdev, &nvbo->bo, size,
                           ttm_bo_type_device, &nvbo->placement,
-                          align >> PAGE_SHIFT, 0, false, NULL, acc_size,
+                          align >> PAGE_SHIFT, 0, false, NULL, acc_size, NULL,
                           nouveau_bo_del_ttm);
         if (ret) {
                 /* ttm will call nouveau_bo_del_ttm if it fails.. */
diff --git a/drivers/gpu/drm/radeon/radeon_object.c b/drivers/gpu/drm/radeon/radeon_object.c
index df6a4dbd93f8..1affbc954c56 100644
--- a/drivers/gpu/drm/radeon/radeon_object.c
+++ b/drivers/gpu/drm/radeon/radeon_object.c
@@ -155,7 +155,7 @@ retry:
         mutex_lock(&rdev->vram_mutex);
         r = ttm_bo_init(&rdev->mman.bdev, &bo->tbo, size, type,
                         &bo->placement, page_align, 0, !kernel, NULL,
-                        acc_size, &radeon_ttm_bo_destroy);
+                        acc_size, NULL, &radeon_ttm_bo_destroy);
         mutex_unlock(&rdev->vram_mutex);
         if (unlikely(r != 0)) {
                 if (r != -ERESTARTSYS) {
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 1f5c67c579cf..36792bd4da77 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -343,6 +343,16 @@ static int ttm_bo_add_ttm(struct ttm_buffer_object *bo, bool zero_alloc)
                 if (unlikely(bo->ttm == NULL))
                         ret = -ENOMEM;
                 break;
+        case ttm_bo_type_sg:
+                bo->ttm = bdev->driver->ttm_tt_create(bdev, bo->num_pages << PAGE_SHIFT,
+                                                      page_flags | TTM_PAGE_FLAG_SG,
+                                                      glob->dummy_read_page);
+                if (unlikely(bo->ttm == NULL)) {
+                        ret = -ENOMEM;
+                        break;
+                }
+                bo->ttm->sg = bo->sg;
+                break;
         default:
                 pr_err("Illegal buffer object type\n");
                 ret = -EINVAL;
@@ -1169,6 +1179,7 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
                 bool interruptible,
                 struct file *persistent_swap_storage,
                 size_t acc_size,
+                struct sg_table *sg,
                 void (*destroy) (struct ttm_buffer_object *))
 {
         int ret = 0;
@@ -1223,6 +1234,7 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
         bo->seq_valid = false;
         bo->persistent_swap_storage = persistent_swap_storage;
         bo->acc_size = acc_size;
+        bo->sg = sg;
         atomic_inc(&bo->glob->bo_count);
 
         ret = ttm_bo_check_placement(bo, placement);
@@ -1233,7 +1245,8 @@ int ttm_bo_init(struct ttm_bo_device *bdev,
          * For ttm_bo_type_device buffers, allocate
          * address space from the device.
          */
-        if (bo->type == ttm_bo_type_device) {
+        if (bo->type == ttm_bo_type_device ||
+            bo->type == ttm_bo_type_sg) {
                 ret = ttm_bo_setup_vm(bo);
                 if (ret)
                         goto out_err;
@@ -1312,7 +1325,7 @@ int ttm_bo_create(struct ttm_bo_device *bdev,
 
         ret = ttm_bo_init(bdev, bo, size, type, placement, page_alignment,
                                 buffer_start, interruptible,
-                                persistent_swap_storage, acc_size, NULL);
+                          persistent_swap_storage, acc_size, NULL, NULL);
         if (likely(ret == 0))
                 *p_bo = bo;
 
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
index a37abb581cbb..22bf9a21ec71 100644
--- a/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
+++ b/drivers/gpu/drm/vmwgfx/vmwgfx_resource.c
@@ -1567,7 +1567,7 @@ int vmw_dmabuf_init(struct vmw_private *dev_priv,
         ret = ttm_bo_init(bdev, &vmw_bo->base, size,
                           ttm_bo_type_device, placement,
                           0, 0, interruptible,
-                          NULL, acc_size, bo_free);
+                          NULL, acc_size, NULL, bo_free);
         return ret;
 }
 
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 974c8f801c39..e15f2a89a270 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -124,11 +124,15 @@ struct ttm_mem_reg {
  *
  * @ttm_bo_type_kernel: These buffers are like ttm_bo_type_device buffers,
  * but they cannot be accessed from user-space. For kernel-only use.
+ *
+ * @ttm_bo_type_sg: Buffer made from dmabuf sg table shared with another
+ * driver.
  */
 
 enum ttm_bo_type {
         ttm_bo_type_device,
-        ttm_bo_type_kernel
+        ttm_bo_type_kernel,
+        ttm_bo_type_sg
 };
 
 struct ttm_tt;
@@ -271,6 +275,8 @@ struct ttm_buffer_object {
 
         unsigned long offset;
         uint32_t cur_placement;
+
+        struct sg_table *sg;
 };
 
 /**
@@ -503,6 +509,7 @@ extern int ttm_bo_init(struct ttm_bo_device *bdev,
                         bool interrubtible,
                         struct file *persistent_swap_storage,
                         size_t acc_size,
+                        struct sg_table *sg,
                         void (*destroy) (struct ttm_buffer_object *));
 
 /**
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index d43e892307ff..a05f1b55714d 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -81,6 +81,7 @@ struct ttm_backend_func {
 #define TTM_PAGE_FLAG_PERSISTENT_SWAP (1 << 5)
 #define TTM_PAGE_FLAG_ZERO_ALLOC      (1 << 6)
 #define TTM_PAGE_FLAG_DMA32           (1 << 7)
+#define TTM_PAGE_FLAG_SG              (1 << 8)
 
 enum ttm_caching_state {
         tt_uncached,
@@ -116,6 +117,7 @@ struct ttm_tt {
         struct page **pages;
         uint32_t page_flags;
         unsigned long num_pages;
+        struct sg_table *sg; /* for SG objects via dma-buf */
         struct ttm_bo_global *glob;
         struct ttm_backend *be;
         struct file *swap_storage;