drm/vmwgfx: Add support for imported Fence File Descriptor

This allows vmwgfx to wait on a fence created by another
device.

v2:
* Remove special handling for vmwgfx fence and just use dma_fence_wait()
* Use interruptible waits
* Added function documentation

Signed-off-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Deepak Singh Rawat <drawat@vmware.com>
Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com>

drivers/gpu/drm/vmwgfx/vmwgfx_execbuf.c

@@ -24,6 +24,7 @@
  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  *
  **************************************************************************/
+#include <linux/sync_file.h>
 
 #include "vmwgfx_drv.h"
 #include "vmwgfx_reg.h"
@@ -4414,6 +4415,7 @@ int vmw_execbuf_ioctl(struct drm_device *dev, unsigned long data,
 	static const size_t copy_offset[] = {
 		offsetof(struct drm_vmw_execbuf_arg, context_handle),
 		sizeof(struct drm_vmw_execbuf_arg)};
+	struct dma_fence *in_fence = NULL;
 
 	if (unlikely(size < copy_offset[0])) {
 		DRM_ERROR("Invalid command size, ioctl %d\n",
@@ -4453,6 +4455,21 @@ int vmw_execbuf_ioctl(struct drm_device *dev, unsigned long data,
 		break;
 	}
 
+
+	/* If imported a fence FD from elsewhere, then wait on it */
+	if (arg.flags & DRM_VMW_EXECBUF_FLAG_IMPORT_FENCE_FD) {
+		in_fence = sync_file_get_fence(arg.imported_fence_fd);
+
+		if (!in_fence) {
+			DRM_ERROR("Cannot get imported fence\n");
+			return -EINVAL;
+		}
+
+		ret = vmw_wait_dma_fence(dev_priv->fman, in_fence);
+		if (ret)
+			goto out;
+	}
+
 	ret = ttm_read_lock(&dev_priv->reservation_sem, true);
 	if (unlikely(ret != 0))
 		return ret;
@@ -4465,9 +4482,12 @@ int vmw_execbuf_ioctl(struct drm_device *dev, unsigned long data,
 				  NULL);
 	ttm_read_unlock(&dev_priv->reservation_sem);
 	if (unlikely(ret != 0))
-		return ret;
+		goto out;
 
 	vmw_kms_cursor_post_execbuf(dev_priv);
 
-	return 0;
+out:
+	if (in_fence)
+		dma_fence_put(in_fence);
+	return ret;
 }

drivers/gpu/drm/vmwgfx/vmwgfx_fence.c

@@ -644,6 +644,51 @@ int vmw_user_fence_create(struct drm_file *file_priv,
 }
 
 
+/**
+ * vmw_wait_dma_fence - Wait for a dma fence
+ *
+ * @fman: pointer to a fence manager
+ * @fence: DMA fence to wait on
+ *
+ * This function handles the case when the fence is actually a fence
+ * array.  If that's the case, it'll wait on each of the child fence
+ */
+int vmw_wait_dma_fence(struct vmw_fence_manager *fman,
+		       struct dma_fence *fence)
+{
+	struct dma_fence_array *fence_array;
+	int ret = 0;
+	int i;
+
+
+	if (dma_fence_is_signaled(fence))
+		return 0;
+
+	if (!dma_fence_is_array(fence))
+		return dma_fence_wait(fence, true);
+
+	/* From i915: Note that if the fence-array was created in
+	 * signal-on-any mode, we should *not* decompose it into its individual
+	 * fences. However, we don't currently store which mode the fence-array
+	 * is operating in. Fortunately, the only user of signal-on-any is
+	 * private to amdgpu and we should not see any incoming fence-array
+	 * from sync-file being in signal-on-any mode.
+	 */
+
+	fence_array = to_dma_fence_array(fence);
+	for (i = 0; i < fence_array->num_fences; i++) {
+		struct dma_fence *child = fence_array->fences[i];
+
+		ret = dma_fence_wait(child, true);
+
+		if (ret < 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+
 /**
  * vmw_fence_fifo_down - signal all unsignaled fence objects.
  */

drivers/gpu/drm/vmwgfx/vmwgfx_fence.h

@@ -28,6 +28,7 @@
 #ifndef _VMWGFX_FENCE_H_
 
 #include <linux/dma-fence.h>
+#include <linux/dma-fence-array.h>
 
 #define VMW_FENCE_WAIT_TIMEOUT (5*HZ)
 
@@ -102,6 +103,9 @@ extern int vmw_user_fence_create(struct drm_file *file_priv,
 				 struct vmw_fence_obj **p_fence,
 				 uint32_t *p_handle);
 
+extern int vmw_wait_dma_fence(struct vmw_fence_manager *fman,
+			      struct dma_fence *fence);
+
 extern void vmw_fence_fifo_up(struct vmw_fence_manager *fman);
 
 extern void vmw_fence_fifo_down(struct vmw_fence_manager *fman);