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>

2 files changed, 10 insertions, 1 deletions

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;