vhost-net devices might keep track of last descriptors indices by
themselves, and assuming they initially start at 0, but that is not the
case for vhost-scsi. Initial last descriptor indices are set via
VHOST_USER_SET_VRING_BASE message, and we cannot possibly predict what
will they be. Setting these to vqueue->used->idx is also not an option,
because there might be some yet unprocessed requests between these and
the actual last_idx. This patch adds API for getting/setting last
descriptor indices of vrings, so that they can be synchronized between
user-device and rte_vhost.
The last_idx flow could be as following:
* vhost start,
* received SET_VRING_BASE msg, last_idx is set on rte_vhost side,
* created user-device, last_idx pulled from rte_vhost,
* requests are being processed by user-device, last_idx changes,
* destroyed user-device, last_idx pushed to rte_vhost,
* at this point, vrings could be recreated and another SET_VRING_BASE
message could arrive, so last_idx would be set
* recreated user-device, last_idx pulled from rte_vhost.
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojac...@intel.com>
Signed-off-by: Tomasz Kulasek <tomaszx.kula...@intel.com>
---
lib/librte_vhost/rte_vhost.h | 24 ++++++++++++++++++++++++
lib/librte_vhost/vhost.c | 27 +++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
diff --git a/lib/librte_vhost/rte_vhost.h b/lib/librte_vhost/rte_vhost.h
index d33206997..b9ba058d1 100644
--- a/lib/librte_vhost/rte_vhost.h
+++ b/lib/librte_vhost/rte_vhost.h
@@ -62,6 +62,9 @@ struct rte_vhost_vring {
int kickfd;
uint16_t size;
+
+ uint16_t last_avail_idx;
+ uint16_t last_used_idx;
};
/**
@@ -434,6 +437,27 @@ int rte_vhost_vring_call(int vid, uint16_t vring_idx);
*/
uint32_t rte_vhost_rx_queue_count(int vid, uint16_t qid);
+/**
+ * Set id of the last descriptors in avail and used guest vrings.
+ *
+ * In case user application operates directly on buffers, it should use this
+ * function on device destruction to retrieve the same values later on in
device
+ * creation via rte_vhost_get_vhost_vring(int, uint16_t, struct
rte_vhost_vring *)
+ *
+ * @param vid
+ * vhost device ID
+ * @param vring_idx
+ * vring index
+ * @param last_avail_idx
+ * id of the last descriptor in avail ring to be set
+ * @param last_used_idx
+ * id of the last descriptor in used ring to be set
+ * @return
+ * 0 on success, -1 on failure
+ */
+int rte_vhost_set_vhost_vring_last_idx(int vid, uint16_t vring_idx,
+ uint16_t last_avail_idx, uint16_t last_used_idx);
+
#ifdef __cplusplus
}
#endif
diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c
index a407067e2..a82dc5a62 100644
--- a/lib/librte_vhost/vhost.c
+++ b/lib/librte_vhost/vhost.c
@@ -512,6 +512,9 @@ rte_vhost_get_vhost_vring(int vid, uint16_t vring_idx,
vring->kickfd = vq->kickfd;
vring->size = vq->size;
+ vring->last_avail_idx = vq->last_avail_idx;
+ vring->last_used_idx = vq->last_used_idx;
+
return 0;
}
@@ -627,3 +630,27 @@ rte_vhost_rx_queue_count(int vid, uint16_t qid)
return *((volatile uint16_t *)&vq->avail->idx) - vq->last_avail_idx;
}
+
+int
+rte_vhost_set_vhost_vring_last_idx(int vid, uint16_t vring_idx,
+ uint16_t last_avail_idx, uint16_t last_used_idx)
+{
+ struct virtio_net *dev;
+ struct vhost_virtqueue *vq;
+
+ dev = get_device(vid);
+ if (!dev)
+ return -1;
+
+ if (vring_idx >= VHOST_MAX_VRING)
+ return -1;
+
+ vq = dev->virtqueue[vring_idx];
+ if (!vq)
+ return -1;
+
+ vq->last_avail_idx = last_avail_idx;
+ vq->last_used_idx = last_used_idx;
+
+ return 0;
+}
--
2.14.1
