[PATCH v3 2/7] virtio-gpu: add & use virtio_gpu_queue_fenced_ctrl_buffer

Gerd Hoffmann
2015-10-02T11:58:40Z

Add helper function to handle the submission of fenced control requests.
Make sure we initialize the fence while holding the virtqueue lock, so
requests can't be reordered.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
drivers/gpu/drm/virtio/virtgpu_fence.c | 2 +-
drivers/gpu/drm/virtio/virtgpu_vq.c | 40 +++++++++++++++++++++++++++++-----
2 files changed, 35 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/virtio/virtgpu_fence.c b/drivers/gpu/drm/virtio/virtgpu_fence.c
index 1da6326..793ad9f 100644
--- a/drivers/gpu/drm/virtio/virtgpu_fence.c
+++ b/drivers/gpu/drm/virtio/virtgpu_fence.c
@@ -81,7 +81,7 @@ int virtio_gpu_fence_emit(struct virtio_gpu_device *vgdev,
struct virtio_gpu_fence_driver *drv = &vgdev->fence_drv;
unsigned long irq_flags;

- *fence = kmalloc(sizeof(struct virtio_gpu_fence), GFP_KERNEL);
+ *fence = kmalloc(sizeof(struct virtio_gpu_fence), GFP_ATOMIC);
if ((*fence) == NULL)
return -ENOMEM;

diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c
index 5b9bc24..ee25e9a 100644
--- a/drivers/gpu/drm/virtio/virtgpu_vq.c
+++ b/drivers/gpu/drm/virtio/virtgpu_vq.c
@@ -347,6 +347,38 @@ static int virtio_gpu_queue_ctrl_buffer(struct virtio_gpu_device *vgdev,
return rc;
}

+static int virtio_gpu_queue_fenced_ctrl_buffer(struct virtio_gpu_device *vgdev,
+ struct virtio_gpu_vbuffer *vbuf,
+ struct virtio_gpu_ctrl_hdr *hdr,
+ struct virtio_gpu_fence **fence)
+{
+ struct virtqueue *vq = vgdev->ctrlq.vq;
+ int rc;
+
+again:
+ spin_lock(&vgdev->ctrlq.qlock);
+
+ /*
+ * Make sure we have enouth space in the virtqueue. If not
+ * wait here until we have.
+ *
+ * Without that virtio_gpu_queue_ctrl_buffer_nolock might have
+ * to wait for free space, which can result in fence ids being
+ * submitted out-of-order.
+ */
+ if (vq->num_free < 3) {
+ spin_unlock(&vgdev->ctrlq.qlock);
+ wait_event(vgdev->ctrlq.ack_queue, vq->num_free >= 3);
+ goto again;
+ }
+
+ if (fence)
+ virtio_gpu_fence_emit(vgdev, hdr, fence);
+ rc = virtio_gpu_queue_ctrl_buffer_locked(vgdev, vbuf);
+ spin_unlock(&vgdev->ctrlq.qlock);
+ return rc;
+}
+
static int virtio_gpu_queue_cursor(struct virtio_gpu_device *vgdev,
struct virtio_gpu_vbuffer *vbuf)
{
@@ -499,9 +531,7 @@ void virtio_gpu_cmd_transfer_to_host_2d(struct virtio_gpu_device *vgdev,
cmd_p->r.x = x;
cmd_p->r.y = y;

- if (fence)
- virtio_gpu_fence_emit(vgdev, &cmd_p->hdr, fence);
- virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
+ virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, &cmd_p->hdr, fence);
}

static void
@@ -524,9 +554,7 @@ virtio_gpu_cmd_resource_attach_backing(struct virtio_gpu_device *vgdev,
vbuf->data_buf = ents;
vbuf->data_size = sizeof(*ents) * nents;

- if (fence)
- virtio_gpu_fence_emit(vgdev, &cmd_p->hdr, fence);
- virtio_gpu_queue_ctrl_buffer(vgdev, vbuf);
+ virtio_gpu_queue_fenced_ctrl_buffer(vgdev, vbuf, &cmd_p->hdr, fence);
}

static void virtio_gpu_cmd_get_display_info_cb(struct virtio_gpu_device *vgdev,
--
1.8.3.1