> When running drm-misc-next you should be able to test whenever that'll
> actually work without any virtio-gpu driver changes.
I did some experimentation with the Chrome OS kernel-next branch
(based on v5.4-rc3) plus drm-misc-next. I looked at both the chromeos
downstream virtio-wayland driver as well as the virtio-vdec driver
that was recently proposed to upstream.
Using the dma address of buffers generally works. However, it does
require the addition of some synchronization in the virtio-gpu driver
to prevent races between the virtio-gpu device registering the buffer
with the guest dma address (which happens with the ATTACH_BACKING
command) and other virtio devices using the guest dma address as a
buffer identifier. I've included a patch that adds this
synchronization.
Signed-off-by: David Stevens <stevensd@xxxxxxxxxxxx>
---
drivers/gpu/drm/virtio/virtgpu_drv.h | 2 +
drivers/gpu/drm/virtio/virtgpu_object.c | 15 +++++-
drivers/gpu/drm/virtio/virtgpu_vq.c | 64 +++++++++++++++++++++----
3 files changed, 71 insertions(+), 10 deletions(-)
diff --git a/drivers/gpu/drm/virtio/virtgpu_drv.h
b/drivers/gpu/drm/virtio/virtgpu_drv.h
index 314e02f94d9c4..00a2c0e6b6382 100644
--- a/drivers/gpu/drm/virtio/virtgpu_drv.h
+++ b/drivers/gpu/drm/virtio/virtgpu_drv.h
@@ -72,6 +72,8 @@ struct virtio_gpu_object {
uint32_t mapped;
bool dumb;
bool created;
+
+ bool attach_backing_complete;
};
#define gem_to_virtio_gpu_obj(gobj) \
container_of((gobj), struct virtio_gpu_object, base.base)
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c
b/drivers/gpu/drm/virtio/virtgpu_object.c
index 017a9e0fc3bb8..812a0a48f6385 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -75,13 +75,26 @@ static void virtio_gpu_free_object(struct
drm_gem_object *obj)
drm_gem_shmem_free_object(obj);
}
+int virtio_gpu_gem_object_pin(struct drm_gem_object *obj)
+{
+ struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(obj);
+ struct virtio_gpu_device *vgdev = obj->dev->dev_private;
+
+ if (!bo->attach_backing_complete)
+ wait_event(vgdev->resp_wq, bo->attach_backing_complete);
+ if (!bo->attach_backing_complete)
+ return -EFAULT;
+
+ return drm_gem_shmem_pin(obj);
+}
+
static const struct drm_gem_object_funcs virtio_gpu_gem_funcs = {
.free = virtio_gpu_free_object,
.open = virtio_gpu_gem_object_open,
.close = virtio_gpu_gem_object_close,
.print_info = drm_gem_shmem_print_info,
- .pin = drm_gem_shmem_pin,
+ .pin = virtio_gpu_gem_object_pin,
.unpin = drm_gem_shmem_unpin,
.get_sg_table = drm_gem_shmem_get_sg_table,
.vmap = drm_gem_shmem_vmap,
diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c
b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 80176f379ad51..8bc2359a6d625 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -579,26 +579,42 @@ void virtio_gpu_cmd_transfer_to_host_2d(struct
virtio_gpu_device *vgdev,
virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, &cmd_p->hdr, fence);
}
+static void
+virtio_gpu_cmd_resource_attach_backing_cb(struct virtio_gpu_device *vgdev,
+ struct virtio_gpu_vbuffer *vbuf)
+{
+ struct virtio_gpu_object_array *objs = vbuf->objs;
+ struct virtio_gpu_object *bo = gem_to_virtio_gpu_obj(objs->objs[0]);
+
+ bo->attach_backing_complete = true;
+ wake_up_all(&vgdev->resp_wq);
+}
+
static void
virtio_gpu_cmd_resource_attach_backing(struct virtio_gpu_device *vgdev,
- uint32_t resource_id,
+ struct virtio_gpu_object *bo,
struct virtio_gpu_mem_entry *ents,
uint32_t nents,
+ struct virtio_gpu_object_array *objs,
struct virtio_gpu_fence *fence)
{
struct virtio_gpu_resource_attach_backing *cmd_p;
struct virtio_gpu_vbuffer *vbuf;
- cmd_p = virtio_gpu_alloc_cmd(vgdev, &vbuf, sizeof(*cmd_p));
+ cmd_p = virtio_gpu_alloc_cmd_resp(
+ vgdev, virtio_gpu_cmd_resource_attach_backing_cb, &vbuf,
+ sizeof(*cmd_p), sizeof(struct virtio_gpu_ctrl_hdr), NULL);
memset(cmd_p, 0, sizeof(*cmd_p));
cmd_p->hdr.type = cpu_to_le32(VIRTIO_GPU_CMD_RESOURCE_ATTACH_BACKING);
- cmd_p->resource_id = cpu_to_le32(resource_id);
+ cmd_p->resource_id = cpu_to_le32(bo->hw_res_handle);
cmd_p->nr_entries = cpu_to_le32(nents);
vbuf->data_buf = ents;
vbuf->data_size = sizeof(*ents) * nents;
+ vbuf->objs = objs;
+
virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, &cmd_p->hdr, fence);
}
@@ -1048,9 +1064,10 @@ int virtio_gpu_object_attach(struct
virtio_gpu_device *vgdev,
struct virtio_gpu_fence *fence)
{
bool use_dma_api = !virtio_has_iommu_quirk(vgdev->vdev);
+ struct virtio_gpu_object_array *objs = NULL;
struct virtio_gpu_mem_entry *ents;
struct scatterlist *sg;
- int si, nents, ret;
+ int si, nents, ret = 0;
if (WARN_ON_ONCE(!obj->created))
return -EINVAL;
@@ -1063,8 +1080,8 @@ int virtio_gpu_object_attach(struct
virtio_gpu_device *vgdev,
obj->pages = drm_gem_shmem_get_sg_table(&obj->base.base);
if (obj->pages == NULL) {
- drm_gem_shmem_unpin(&obj->base.base);
- return -EINVAL;
+ ret = -EINVAL;
+ goto err_unpin;
}
if (use_dma_api) {
@@ -1081,7 +1098,8 @@ int virtio_gpu_object_attach(struct
virtio_gpu_device *vgdev,
GFP_KERNEL);
if (!ents) {
DRM_ERROR("failed to allocate ent list\n");
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto err_unmap;
}
for_each_sg(obj->pages->sgl, sg, nents, si) {
@@ -1092,10 +1110,38 @@ int virtio_gpu_object_attach(struct
virtio_gpu_device *vgdev,
ents[si].padding = 0;
}
- virtio_gpu_cmd_resource_attach_backing(vgdev, obj->hw_res_handle,
+ objs = virtio_gpu_array_alloc(1);
+ if (!objs) {
+ ret = -ENOMEM;
+ goto err_free_ents;
+ }
+ virtio_gpu_array_add_obj(objs, &obj->base.base);
+
+ if (fence) {
+ ret = virtio_gpu_array_lock_resv(objs);
+ if (ret != 0)
+ goto err_put_objs;
+ }
+
+ virtio_gpu_cmd_resource_attach_backing(vgdev, obj,
ents, nents,
- fence);
+ objs, fence);
return 0;
+
+err_put_objs:
+ virtio_gpu_array_put_free(objs);
+err_free_ents:
+ kfree(ents);
+err_unmap:
+ if (use_dma_api) {
+ dma_unmap_sg(vgdev->vdev->dev.parent,
+ obj->pages->sgl, obj->pages->nents,
+ DMA_TO_DEVICE);
+ obj->mapped = 0;
+ }
+err_unpin:
+ drm_gem_shmem_unpin(&obj->base.base);
+ return ret;
}
void virtio_gpu_object_detach(struct virtio_gpu_device *vgdev,
--
2.24.0.rc0.303.g954a862665-goog
