[Minios-devel] [UNIKRAFT PATCH v2 10/16] plat/xen/drivers/blk: Write queues information to Xenstore

[Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>]

This patch introduces the last step of start operation:
Writing to Xenstore information about each configured queue
(ring grant reference and event channel) in order to connect to Backend.

Signed-off-by: Roxana Nicolescu <nicolescu.roxana1996@xxxxxxxxx>
---
 plat/xen/drivers/blk/blkfront_xb.h |   2 +
 plat/xen/drivers/blk/blkfront_xs.c | 196 +++++++++++++++++++++++++++++++++++++
 2 files changed, 198 insertions(+)

diff --git a/plat/xen/drivers/blk/blkfront_xb.h 
b/plat/xen/drivers/blk/blkfront_xb.h
index 60070d9c..e1b8b199 100644
--- a/plat/xen/drivers/blk/blkfront_xb.h
+++ b/plat/xen/drivers/blk/blkfront_xb.h
@@ -65,6 +65,7 @@ void blkfront_xb_fini(struct blkfront_dev *dev);
 int blkfront_xb_write_nb_queues(struct blkfront_dev *dev);
 
 /**
+ * Write ring entries to Xenstore.
  * Device changes its state to Connected.
  * It waits until the backend is connected.
  *
@@ -76,6 +77,7 @@ int blkfront_xb_connect(struct blkfront_dev *dev);
  * Reinitialize the connection with the backend.
  * The following states are:
  *     Connected -> Closing -> Closed -> Initializing.
+ * Delete ring entries
  *
  * Return 0 on success, a negative errno value on error.
  */
diff --git a/plat/xen/drivers/blk/blkfront_xs.c 
b/plat/xen/drivers/blk/blkfront_xs.c
index 5ddb38d0..86aee13b 100644
--- a/plat/xen/drivers/blk/blkfront_xs.c
+++ b/plat/xen/drivers/blk/blkfront_xs.c
@@ -164,6 +164,189 @@ out:
        return err;
 }
 
+
+/* Write info for a specific queue in xenstore.
+ * If there is only one queue, the path does not
+ * include queue-<queue-id>.
+ **/
+static int blkfront_xb_write_ring_info(struct blkfront_dev *dev,
+               uint16_t queue_id,
+               xenbus_transaction_t xbt)
+{
+       struct xenbus_device *xendev;
+       char *node_ring_ref = NULL;
+       char *node_evtchn = NULL;
+       int err = 0;
+
+       UK_ASSERT(dev != NULL);
+       xendev = dev->xendev;
+
+       if (queue_id == 0 && dev->nb_queues == 1) {
+               err = asprintf(&node_ring_ref, "ring-ref");
+               if (err <= 0) {
+                       uk_pr_err("Failed to format ring_ref path: %d\n", err);
+                       goto out;
+               }
+
+               err = asprintf(&node_evtchn, "event-channel");
+               if (err <= 0) {
+                       uk_pr_err("Failed to format event-channel path: %d\n",
+                                       err);
+                       goto out;
+               }
+       } else {
+               err = asprintf(&node_ring_ref, "queue-%"PRIu16"/ring-ref",
+                               queue_id);
+               if (err <= 0) {
+                       uk_pr_err("Failed to format ring_ref path: %d\n", err);
+                       goto out;
+               }
+
+               err = asprintf(&node_evtchn, "queue-%"PRIu16"/event-channel",
+                               queue_id);
+               if (err <= 0) {
+                       uk_pr_err("Failed to format event-channel path: %d\n",
+                                       err);
+                       goto out;
+               }
+       }
+
+       err = xs_printf(xbt, xendev->nodename,
+                               node_evtchn,
+                               "%u",
+                               dev->blkdev._queue[queue_id]->evtchn);
+       if (err <= 0) {
+               uk_pr_err("Failed to write event-channel: %d\n", err);
+               goto out;
+       }
+
+       err = xs_printf(xbt, xendev->nodename,
+                       node_ring_ref,
+                       "%u",
+                       dev->blkdev._queue[queue_id]->ring_ref);
+       if (err <= 0) {
+               uk_pr_err("Failed to write ring_ref: %d\n", err);
+               goto out;
+       }
+
+       err = 0;
+
+out:
+       free(node_evtchn);
+       free(node_ring_ref);
+       return err;
+}
+
+/* Delete ring entry */
+static int blkfront_xb_delete_ring_info(struct blkfront_dev *dev,
+               uint16_t queue_id)
+{
+       struct xenbus_device *xendev;
+       char *node_ring_ref = NULL;
+       char *node_evtchn = NULL;
+       int err = 0;
+
+       UK_ASSERT(dev);
+       xendev = dev->xendev;
+
+       if (queue_id == 0 && dev->nb_queues == 1) {
+               err = asprintf(&node_ring_ref, "%s/ring-ref",
+                               xendev->nodename);
+               if (err <= 0) {
+                       uk_pr_err("Failed to format ring_ref_path: %d\n", err);
+                       goto out;
+               }
+
+               err = asprintf(&node_evtchn, "%s/event-channel",
+                               xendev->nodename);
+               if (err <= 0) {
+                       uk_pr_err("Failed to format event-channel path: %d\n",
+                                       err);
+                       goto out;
+               }
+       } else {
+               err = asprintf(&node_ring_ref, "%s/queue-%"PRIu16"/ring-ref",
+                               xendev->nodename,
+                               queue_id);
+               if (err <= 0) {
+                       uk_pr_err("Failed to format ring_ref_path: %d\n", err);
+                       goto out;
+               }
+
+               err = asprintf(&node_evtchn, "%s/queue-%"PRIu16"/event-channel",
+                               xendev->nodename,
+                               queue_id);
+               if (err <= 0) {
+                       uk_pr_err("Failed to format event-channel path: %d\n",
+                                       err);
+                       goto out;
+               }
+       }
+
+       err = xs_rm(XBT_NIL, node_ring_ref);
+       if (err)
+               uk_pr_err("Failed to remove ring_ref from xs: %d\n", err);
+
+       err = xs_rm(XBT_NIL, node_evtchn);
+       if (err)
+               uk_pr_err("Failed to remove event-channel from xs: %d\n", err);
+out:
+       free(node_evtchn);
+       free(node_ring_ref);
+       return err;
+}
+
+static int blkfront_xb_write_rings_info(struct blkfront_dev *dev)
+{
+       xenbus_transaction_t xbt = 0;
+       int err = 0;
+
+       UK_ASSERT(dev != NULL);
+
+       err = xs_transaction_start(&xbt);
+       if (err)
+               goto abort_transaction;
+
+       for (uint16_t queue_id = 0; queue_id < dev->nb_queues; ++queue_id) {
+               err = blkfront_xb_write_ring_info(dev, queue_id, xbt);
+               if (err) {
+                       uk_pr_err("Failed to write queue%"PRIu16" to xs: %d\n",
+                                       queue_id,
+                                       err);
+                       goto abort_transaction;
+               }
+       }
+
+       err = xs_transaction_end(xbt, 0);
+       if (err)
+               uk_pr_err("Failed to end transaction: %d\n", err);
+
+       return err;
+
+abort_transaction:
+       xs_transaction_end(xbt, 1);
+       return err;
+}
+
+static int blkfront_xb_delete_rings_info(struct blkfront_dev *dev)
+{
+       int err = 0;
+
+       UK_ASSERT(dev != NULL);
+
+       for (uint16_t queue_id = 0; queue_id < dev->nb_queues; ++queue_id) {
+               err = blkfront_xb_delete_ring_info(dev, queue_id);
+               if (err) {
+                       uk_pr_err("Failed to delete ring_info for q-%"
+                                       PRIu16 ": %d\n",
+                                       queue_id, err);
+                       return err;
+               }
+       }
+
+       return err;
+}
+
 #define WAIT_BE_STATE_CHANGE_WHILE_COND(state_cond) \
        do { \
                err = xs_read_integer(XBT_NIL, back_state_path,\
@@ -253,6 +436,13 @@ int blkfront_xb_connect(struct blkfront_dev *blkdev)
        UK_ASSERT(blkdev != NULL);
        xendev = blkdev->xendev;
 
+       err = blkfront_xb_write_rings_info(blkdev);
+       if (err) {
+               uk_pr_err("Failed to write rings info to xenstore: %d\n.",
+                               err);
+               return err;
+       }
+
        err = xenbus_switch_state(XBT_NIL, xendev, XenbusStateConnected);
        if (err)
                goto err;
@@ -289,6 +479,12 @@ int blkfront_xb_disconnect(struct blkfront_dev *blkdev)
                goto out;
        }
 
+       err = blkfront_xb_delete_rings_info(blkdev);
+       if (err) {
+               uk_pr_err("Failed to delete rings info: %d\n", err);
+               goto out;
+       }
+
 out:
        return err;
 }
-- 
2.11.0


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