[Minios-devel] [UNIKRAFT PATCH 11/12] 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         | 82 ++++++++++++++++++++++++++++++++
 2 files changed, 86 insertions(+)

diff --git a/plat/drivers/include/virtio/virtio_blk.h 
b/plat/drivers/include/virtio/virtio_blk.h
index e2d28928..1b8dffd3 100644
--- a/plat/drivers/include/virtio/virtio_blk.h
+++ b/plat/drivers/include/virtio/virtio_blk.h
@@ -39,6 +39,10 @@
 /* Device supports multi-queues */
 #define VIRTIO_BLK_F_MQ                12
 
+/* Response status */
+#define VIRTIO_BLK_S_OK                0
+#define VIRTIO_BLK_S_IOERR     1
+#define VIRTIO_BLK_S_UNSUPP    2
 
 struct virtio_blk_config {
        /* Dimension in sectors number */
diff --git a/plat/drivers/virtio/virtio_blk.c b/plat/drivers/virtio/virtio_blk.c
index 5b8972cf..a1d2bd68 100644
--- a/plat/drivers/virtio/virtio_blk.c
+++ b/plat/drivers/virtio/virtio_blk.c
@@ -324,6 +324,87 @@ err:
        return rc;
 }
 
+static int virtio_blkdev_queue_dequeue(struct uk_blkdev_queue *queue,
+               struct uk_blkdev_request **req)
+{
+       int ret = 0;
+       __u32 len;
+       struct uk_blkdev_request *response_req = NULL;
+
+       UK_ASSERT(req);
+       ret = virtqueue_buffer_dequeue(queue->vq, (void **) &response_req,
+                       &len);
+       if (ret < 0) {
+               uk_pr_info("No data available in the queue\n");
+               ret = 0;
+               goto out;
+       }
+
+       /* We need at least one byte for the result status */
+       if (unlikely(len < 1)) {
+               uk_pr_err("Received invalid response size: %u\n", len);
+               return -EINVAL;
+       }
+
+out:
+       *req = response_req;
+       return ret;
+}
+
+static int virtio_blkdev_complete_reqs(struct uk_blkdev *dev,
+               uint16_t queue_id)
+{
+       struct virtio_blk_device *vbdev;
+       struct uk_blkdev_queue *queue;
+       struct uk_blkdev_request *req;
+       int rc = 0;
+
+       UK_ASSERT(dev);
+
+       vbdev = to_virtioblkdev(dev);
+       if (unlikely(queue_id >= vbdev->nb_queues)) {
+               uk_pr_err("Invalid queue_id %"__PRIu16"\n", queue_id);
+               return -EINVAL;
+       }
+
+       queue = &vbdev->qs[queue_id];
+
+       /* 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_refcount_release(&req->state);
+               if (req->cb) {
+                       rc = req->cb(req, req->cookie_callback);
+                       if (rc) {
+                               uk_pr_err("Callback failed %d\n", rc);
+                               goto err_exit;
+                       }
+               }
+       }
+
+       /* 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)
 {
@@ -814,6 +895,7 @@ 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;
 
-- 
2.11.0


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