[Minios-devel] [UNIKRAFT PATCH v3 13/14] plat/drivers: Handle responses from backend for virtio block

[Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>]

This patch introduces the function responsible of processing
responses from the queue.
Responses are popped out from queue until there is nothing to process.

Signed-off-by: Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>
---
 plat/drivers/include/virtio/virtio_blk.h |  4 ++
 plat/drivers/virtio/virtio_blk.c         | 73 ++++++++++++++++++++++++
 2 files changed, 77 insertions(+)

diff --git a/plat/drivers/include/virtio/virtio_blk.h 
b/plat/drivers/include/virtio/virtio_blk.h
index 662418c6..d56c1e13 100644
--- a/plat/drivers/include/virtio/virtio_blk.h
+++ b/plat/drivers/include/virtio/virtio_blk.h
@@ -93,4 +93,8 @@ struct virtio_blk_outhdr {
        __virtio_le64 sector;
 };
 
+/* And this is the final byte of the write scatter-gather list. */
+#define VIRTIO_BLK_S_OK                0
+#define VIRTIO_BLK_S_IOERR     1
+
 #endif /* __PLAT_DRV_VIRTIO_BLK_H */
diff --git a/plat/drivers/virtio/virtio_blk.c b/plat/drivers/virtio/virtio_blk.c
index 520cdfbe..85f40ba6 100644
--- a/plat/drivers/virtio/virtio_blk.c
+++ b/plat/drivers/virtio/virtio_blk.c
@@ -338,6 +338,78 @@ err:
        return rc;
 }
 
+static int virtio_blkdev_queue_dequeue(struct uk_blkdev_queue *queue,
+               struct uk_blkreq **req)
+{
+       int ret = 0;
+       __u32 len;
+       struct virtio_blkdev_request *response_req;
+
+       UK_ASSERT(req);
+       *req = NULL;
+
+       ret = virtqueue_buffer_dequeue(queue->vq, (void **) &response_req,
+                       &len);
+       if (ret < 0) {
+               uk_pr_info("No data available in the queue\n");
+               return 0;
+       }
+
+       /* We need at least one byte for the result status */
+       if (unlikely(len < 1)) {
+               uk_pr_err("Received invalid response size: %u\n", len);
+               ret = -EINVAL;
+               goto out;
+       }
+
+       *req = response_req->req;
+       (*req)->result = -response_req->status;
+
+out:
+       uk_free(a, response_req);
+       return ret;
+}
+
+static int virtio_blkdev_complete_reqs(struct uk_blkdev *dev,
+               struct uk_blkdev_queue *queue)
+{
+       struct uk_blkreq *req;
+       int rc = 0;
+
+       UK_ASSERT(dev);
+
+       /* Queue interrupts have to be off when calling receive */
+       UK_ASSERT(!(queue->intr_enabled & VTBLK_INTR_EN));
+
+moretodo:
+       for (;;) {
+               rc = virtio_blkdev_queue_dequeue(queue, &req);
+               if (unlikely(rc < 0)) {
+                       uk_pr_err("Failed to dequeue the request: %d\n", rc);
+                       goto err_exit;
+               }
+
+               if (!req)
+                       break;
+
+               uk_blkreq_finished(req);
+               if (req->cb)
+                       req->cb(req, req->cb_cookie);
+       }
+
+       /* Enable interrupt only when user had previously enabled it */
+       if (queue->intr_enabled & VTBLK_INTR_USR_EN_MASK) {
+               rc = virtqueue_intr_enable(queue->vq);
+               if (rc == 1)
+                       goto moretodo;
+       }
+
+       return 0;
+
+err_exit:
+       return rc;
+}
+
 static int virtio_blkdev_recv_done(struct virtqueue *vq, void *priv)
 {
        struct uk_blkdev_queue *queue = NULL;
@@ -811,6 +883,7 @@ static int virtio_blk_add_dev(struct virtio_dev *vdev)
                return -ENOMEM;
 
        vbdev->vdev = vdev;
+       vbdev->blkdev.finish_reqs = virtio_blkdev_complete_reqs;
        vbdev->blkdev.submit_one = virtio_blkdev_submit_request;
        vbdev->blkdev.dev_ops = &virtio_blkdev_ops;
 
-- 
2.17.1


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