[PATCH 3/4] drm/amdgpu: add independent DMA-buf export v7

Christian König
2019-08-29T14:29:27Z

Add an DMA-buf export implementation independent of the DRM helpers.

This not only avoids the caching of DMA-buf mappings, but also
allows us to use the new dynamic locking approach.

This is also a prerequisite of unpinned DMA-buf handling.

v2: fix unintended recursion, remove debugging leftovers
v3: split out from unpinned DMA-buf work
v4: rebase on top of new no_sgt_cache flag
v5: fix some warnings by including amdgpu_dma_buf.h
v6: fix locking for non amdgpu exports
v7: rebased on new DMA-buf locking patch

Signed-off-by: Christian König <christian.koenig@amd.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c | 172 +++++++++++---------
drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.h | 1 -
drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 1 -
drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 1 +
4 files changed, 97 insertions(+), 78 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
index bf0f00508987..d3d32b75f346 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.c
@@ -34,26 +34,11 @@
#include "amdgpu.h"
#include "amdgpu_display.h"
#include "amdgpu_gem.h"
+#include "amdgpu_dma_buf.h"
#include <drm/amdgpu_drm.h>
#include <linux/dma-buf.h>
#include <linux/dma-fence-array.h>

-/**
- * amdgpu_gem_prime_get_sg_table - &drm_driver.gem_prime_get_sg_table
- * implementation
- * @obj: GEM buffer object (BO)
- *
- * Returns:
- * A scatter/gather table for the pinned pages of the BO's memory.
- */
-struct sg_table *amdgpu_gem_prime_get_sg_table(struct drm_gem_object *obj)
-{
- struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
- int npages = bo->tbo.num_pages;
-
- return drm_prime_pages_to_sg(bo->tbo.ttm->pages, npages);
-}
-
/**
* amdgpu_gem_prime_vmap - &dma_buf_ops.vmap implementation
* @obj: GEM BO
@@ -179,92 +164,126 @@ __dma_resv_make_exclusive(struct dma_resv *obj)
}

/**
- * amdgpu_dma_buf_map_attach - &dma_buf_ops.attach implementation
- * @dma_buf: Shared DMA buffer
+ * amdgpu_dma_buf_attach - &dma_buf_ops.attach implementation
+ *
+ * @dmabuf: DMA-buf where we attach to
+ * @attach: attachment to add
+ *
+ * Add the attachment as user to the exported DMA-buf.
+ */
+static int amdgpu_dma_buf_attach(struct dma_buf *dmabuf,
+ struct dma_buf_attachment *attach)
+{
+ struct drm_gem_object *obj = dmabuf->priv;
+ struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+ struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
+ int r;
+
+ if (attach->dev->driver == adev->dev->driver)
+ return 0;
+
+ r = amdgpu_bo_reserve(bo, false);
+ if (unlikely(r != 0))
+ return r;
+
+ /*
+ * We only create shared fences for internal use, but importers
+ * of the dmabuf rely on exclusive fences for implicitly
+ * tracking write hazards. As any of the current fences may
+ * correspond to a write, we need to convert all existing
+ * fences on the reservation object into a single exclusive
+ * fence.
+ */
+ r = __dma_resv_make_exclusive(bo->tbo.base.resv);
+ if (r)
+ return r;
+
+ bo->prime_shared_count++;
+ amdgpu_bo_unreserve(bo);
+ return 0;
+}
+
+/**
+ * amdgpu_dma_buf_detach - &dma_buf_ops.detach implementation
+ *
+ * @dmabuf: DMA-buf where we remove the attachment from
+ * @attach: the attachment to remove
+ *
+ * Called when an attachment is removed from the DMA-buf.
+ */
+static void amdgpu_dma_buf_detach(struct dma_buf *dmabuf,
+ struct dma_buf_attachment *attach)
+{
+ struct drm_gem_object *obj = dmabuf->priv;
+ struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
+ struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
+
+ if (attach->dev->driver != adev->dev->driver && bo->prime_shared_count)
+ bo->prime_shared_count--;
+}
+
+/**
+ * amdgpu_dma_buf_map - &dma_buf_ops.map_dma_buf implementation
* @attach: DMA-buf attachment
+ * @dir: DMA direction
*
* Makes sure that the shared DMA buffer can be accessed by the target device.
* For now, simply pins it to the GTT domain, where it should be accessible by
* all DMA devices.
*
* Returns:
- * 0 on success or a negative error code on failure.
+ * sg_table filled with the DMA addresses to use or ERR_PRT with negative error
+ * code.
*/
-static int amdgpu_dma_buf_map_attach(struct dma_buf *dma_buf,
- struct dma_buf_attachment *attach)
+static struct sg_table *amdgpu_dma_buf_map(struct dma_buf_attachment *attach,
+ enum dma_data_direction dir)
{
+ struct dma_buf *dma_buf = attach->dmabuf;
struct drm_gem_object *obj = dma_buf->priv;
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
- struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
+ struct sg_table *sgt;
long r;

- r = drm_gem_map_attach(dma_buf, attach);
- if (r)
- return r;
-
- r = amdgpu_bo_reserve(bo, false);
- if (unlikely(r != 0))
- goto error_detach;
-
-
- if (attach->dev->driver != adev->dev->driver) {
- /*
- * We only create shared fences for internal use, but importers
- * of the dmabuf rely on exclusive fences for implicitly
- * tracking write hazards. As any of the current fences may
- * correspond to a write, we need to convert all existing
- * fences on the reservation object into a single exclusive
- * fence.
- */
- r = __dma_resv_make_exclusive(bo->tbo.base.resv);
- if (r)
- goto error_unreserve;
- }
-
- /* pin buffer into GTT */
r = amdgpu_bo_pin(bo, AMDGPU_GEM_DOMAIN_GTT);
if (r)
- goto error_unreserve;
+ return ERR_PTR(r);

- if (attach->dev->driver != adev->dev->driver)
- bo->prime_shared_count++;
+ sgt = drm_prime_pages_to_sg(bo->tbo.ttm->pages, bo->tbo.num_pages);
+ if (IS_ERR(sgt))
+ return sgt;

-error_unreserve:
- amdgpu_bo_unreserve(bo);
+ if (!dma_map_sg_attrs(attach->dev, sgt->sgl, sgt->nents, dir,
+ DMA_ATTR_SKIP_CPU_SYNC))
+ goto error_free;

-error_detach:
- if (r)
- drm_gem_map_detach(dma_buf, attach);
- return r;
+ return sgt;
+
+error_free:
+ sg_free_table(sgt);
+ kfree(sgt);
+ return ERR_PTR(-ENOMEM);
}

/**
- * amdgpu_dma_buf_map_detach - &dma_buf_ops.detach implementation
- * @dma_buf: Shared DMA buffer
+ * amdgpu_dma_buf_unmap - &dma_buf_ops.unmap_dma_buf implementation
* @attach: DMA-buf attachment
+ * @sgt: sg_table to unmap
+ * @dir: DMA direction
*
* This is called when a shared DMA buffer no longer needs to be accessible by
* another device. For now, simply unpins the buffer from GTT.
*/
-static void amdgpu_dma_buf_map_detach(struct dma_buf *dma_buf,
- struct dma_buf_attachment *attach)
+static void amdgpu_dma_buf_unmap(struct dma_buf_attachment *attach,
+ struct sg_table *sgt,
+ enum dma_data_direction dir)
{
- struct drm_gem_object *obj = dma_buf->priv;
+ struct drm_gem_object *obj = attach->dmabuf->priv;
struct amdgpu_bo *bo = gem_to_amdgpu_bo(obj);
- struct amdgpu_device *adev = amdgpu_ttm_adev(bo->tbo.bdev);
- int ret = 0;
-
- ret = amdgpu_bo_reserve(bo, true);
- if (unlikely(ret != 0))
- goto error;

+ dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
+ sg_free_table(sgt);
+ kfree(sgt);
amdgpu_bo_unpin(bo);
- if (attach->dev->driver != adev->dev->driver && bo->prime_shared_count)
- bo->prime_shared_count--;
- amdgpu_bo_unreserve(bo);
-
-error:
- drm_gem_map_detach(dma_buf, attach);
}

/**
@@ -308,10 +327,11 @@ static int amdgpu_dma_buf_begin_cpu_access(struct dma_buf *dma_buf,
}

const struct dma_buf_ops amdgpu_dmabuf_ops = {
- .attach = amdgpu_dma_buf_map_attach,
- .detach = amdgpu_dma_buf_map_detach,
- .map_dma_buf = drm_gem_map_dma_buf,
- .unmap_dma_buf = drm_gem_unmap_dma_buf,
+ .dynamic_mapping = true,
+ .attach = amdgpu_dma_buf_attach,
+ .detach = amdgpu_dma_buf_detach,
+ .map_dma_buf = amdgpu_dma_buf_map,
+ .unmap_dma_buf = amdgpu_dma_buf_unmap,
.release = drm_gem_dmabuf_release,
.begin_cpu_access = amdgpu_dma_buf_begin_cpu_access,
.mmap = drm_gem_dmabuf_mmap,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.h
index 5012e6ab58f1..ce1b3f017451 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_dma_buf.h
@@ -25,7 +25,6 @@

#include <drm/drm_gem.h>

-struct sg_table *amdgpu_gem_prime_get_sg_table(struct drm_gem_object *obj);
struct drm_gem_object *
amdgpu_gem_prime_import_sg_table(struct drm_device *dev,
struct dma_buf_attachment *attach,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index 6b96a5738e57..6b7ad9345b61 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -1397,7 +1397,6 @@ static struct drm_driver kms_driver = {
.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
.gem_prime_export = amdgpu_gem_prime_export,
.gem_prime_import = amdgpu_gem_prime_import,
- .gem_prime_get_sg_table = amdgpu_gem_prime_get_sg_table,
.gem_prime_import_sg_table = amdgpu_gem_prime_import_sg_table,
.gem_prime_vmap = amdgpu_gem_prime_vmap,
.gem_prime_vunmap = amdgpu_gem_prime_vunmap,
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 2f11ebd95528..156f0098d161 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -31,6 +31,7 @@
*/
#include <linux/list.h>
#include <linux/slab.h>
+#include <linux/dma-buf.h>

#include <drm/amdgpu_drm.h>
#include <drm/drm_cache.h>
--
2.17.1