[PATCH v4 3/4] drm/virtio: add in/out fence support for explicit synchronization

Robert Foss
2018-11-05T11:42:12Z

When the execbuf call receives an in-fence it will get the dma_fence
related to that fence fd and wait on it before submitting the draw call.

On the out-fence side we get fence returned by the submitted draw call
and attach it to a sync_file and send the sync_file fd to userspace. On
error -1 is returned to userspace.

Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.com>
Signed-off-by: Robert Foss <robert.foss@collabora.com>
Suggested-by: Rob Herring <robh@kernel.org>
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
---

Changes since v3:
- Move all in_fence handling to the same VIRTGPU_EXECBUF_FENCE_FD_IN block
- Emil: Make sure to always call dma_fence_put()
- Emil: Added r-b

drivers/gpu/drm/virtio/virtgpu_ioctl.c | 81 ++++++++++++++++++++------
1 file changed, 64 insertions(+), 17 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
index 3d497835b0f5..340f2513d829 100644
--- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c
+++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c
@@ -28,6 +28,7 @@
#include <drm/drmP.h>
#include <drm/virtgpu_drm.h>
#include <drm/ttm/ttm_execbuf_util.h>
+#include <linux/sync_file.h>

#include "virtgpu_drv.h"

@@ -105,7 +106,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
struct virtio_gpu_device *vgdev = dev->dev_private;
struct virtio_gpu_fpriv *vfpriv = drm_file->driver_priv;
struct drm_gem_object *gobj;
- struct virtio_gpu_fence *fence;
+ struct virtio_gpu_fence *out_fence;
struct virtio_gpu_object *qobj;
int ret;
uint32_t *bo_handles = NULL;
@@ -114,6 +115,9 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
struct ttm_validate_buffer *buflist = NULL;
int i;
struct ww_acquire_ctx ticket;
+ struct sync_file *sync_file;
+ int in_fence_fd = exbuf->fence_fd;
+ int out_fence_fd = -1;
void *buf;

if (vgdev->has_virgl_3d == false)
@@ -124,6 +128,33 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,

exbuf->fence_fd = -1;

+ if (exbuf->flags & VIRTGPU_EXECBUF_FENCE_FD_IN) {
+ struct dma_fence *in_fence;
+
+ in_fence = sync_file_get_fence(in_fence_fd);
+
+ if (!in_fence)
+ return -EINVAL;
+
+ /*
+ * Wait if the fence is from a foreign context, or if the fence
+ * array contains any fence from a foreign context.
+ */
+ ret = 0;
+ if (!dma_fence_match_context(in_fence, vgdev->fence_drv.context))
+ ret = dma_fence_wait(in_fence, true);
+
+ dma_fence_put(in_fence);
+ if (ret)
+ return ret;
+ }
+
+ if (exbuf->flags & VIRTGPU_EXECBUF_FENCE_FD_OUT) {
+ out_fence_fd = get_unused_fd_flags(O_CLOEXEC);
+ if (out_fence_fd < 0)
+ return out_fence_fd;
+ }
+
INIT_LIST_HEAD(&validate_list);
if (exbuf->num_bo_handles) {

@@ -133,26 +164,22 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
sizeof(struct ttm_validate_buffer),
GFP_KERNEL | __GFP_ZERO);
if (!bo_handles || !buflist) {
- kvfree(bo_handles);
- kvfree(buflist);
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto out_unused_fd;
}

user_bo_handles = (void __user *)(uintptr_t)exbuf->bo_handles;
if (copy_from_user(bo_handles, user_bo_handles,
exbuf->num_bo_handles * sizeof(uint32_t))) {
ret = -EFAULT;
- kvfree(bo_handles);
- kvfree(buflist);
- return ret;
+ goto out_unused_fd;
}

for (i = 0; i < exbuf->num_bo_handles; i++) {
gobj = drm_gem_object_lookup(drm_file, bo_handles[i]);
if (!gobj) {
- kvfree(bo_handles);
- kvfree(buflist);
- return -ENOENT;
+ ret = -ENOENT;
+ goto out_unused_fd;
}

qobj = gem_to_virtio_gpu_obj(gobj);
@@ -161,6 +188,7 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
list_add(&buflist[i].head, &validate_list);
}
kvfree(bo_handles);
+ bo_handles = NULL;
}

ret = virtio_gpu_object_list_validate(&ticket, &validate_list);
@@ -174,28 +202,47 @@ static int virtio_gpu_execbuffer_ioctl(struct drm_device *dev, void *data,
goto out_unresv;
}

- fence = virtio_gpu_fence_alloc(vgdev);
- if (!fence) {
- kfree(buf);
+ out_fence = virtio_gpu_fence_alloc(vgdev);
+ if(!out_fence) {
ret = -ENOMEM;
- goto out_unresv;
+ goto out_memdup;
+ }
+
+ if (out_fence_fd >= 0) {
+ sync_file = sync_file_create(&out_fence->f);
+ if (!sync_file) {
+ dma_fence_put(&out_fence->f);
+ ret = -ENOMEM;
+ goto out_memdup;
+ }
+
+ exbuf->fence_fd = out_fence_fd;
+ fd_install(out_fence_fd, sync_file->file);
}
+
virtio_gpu_cmd_submit(vgdev, buf, exbuf->size,
- vfpriv->ctx_id, &fence);
+ vfpriv->ctx_id, &out_fence);

- ttm_eu_fence_buffer_objects(&ticket, &validate_list, &fence->f);
+ ttm_eu_fence_buffer_objects(&ticket, &validate_list, &out_fence->f);

/* fence the command bo */
virtio_gpu_unref_list(&validate_list);
kvfree(buflist);
- dma_fence_put(&fence->f);
return 0;

+out_memdup:
+ kfree(buf);
out_unresv:
ttm_eu_backoff_reservation(&ticket, &validate_list);
out_free:
virtio_gpu_unref_list(&validate_list);
+out_unused_fd:
+ kvfree(bo_handles);
kvfree(buflist);
+
+ if (out_fence_fd >= 0)
+ put_unused_fd(out_fence_fd);
+
return ret;
}

--
2.17.1