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[Qemu-devel] [PATCH 3/4] libvhost-user: implement VHOST_USER_PROTOCOL_F_
From: |
Stefan Hajnoczi |
Subject: |
[Qemu-devel] [PATCH 3/4] libvhost-user: implement VHOST_USER_PROTOCOL_F_MQ |
Date: |
Fri, 21 Jun 2019 10:40:04 +0100 |
Existing vhost-user device backends, including vhost-user-scsi and
vhost-user-blk, support multiqueue but libvhost-user currently does not
advertise this.
VHOST_USER_PROTOCOL_F_MQ enables the VHOST_USER_GET_QUEUE_NUM request
needed for a vhost-user master to query the number of queues. For
example, QEMU's vhost-user-net master depends on
VHOST_USER_PROTOCOL_F_MQ for multiqueue.
If you're wondering how any device backend with more than one virtqueue
functions today, it's because device types with a fixed number of
virtqueues do not require querying the number of queues. Therefore the
vhost-user master for vhost-user-input with 2 virtqueues, for example,
doesn't actually depend on VHOST_USER_PROTOCOL_F_MQ. It just enables
virtqueues 0 and 1 without asking.
Let there be multiqueue!
Suggested-by: Sebastien Boeuf <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
---
contrib/libvhost-user/libvhost-user.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/contrib/libvhost-user/libvhost-user.c
b/contrib/libvhost-user/libvhost-user.c
index 0c88431e8f..312c54f260 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -1160,7 +1160,8 @@ vu_set_vring_err_exec(VuDev *dev, VhostUserMsg *vmsg)
static bool
vu_get_protocol_features_exec(VuDev *dev, VhostUserMsg *vmsg)
{
- uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD |
+ uint64_t features = 1ULL << VHOST_USER_PROTOCOL_F_MQ |
+ 1ULL << VHOST_USER_PROTOCOL_F_LOG_SHMFD |
1ULL << VHOST_USER_PROTOCOL_F_SLAVE_REQ |
1ULL << VHOST_USER_PROTOCOL_F_HOST_NOTIFIER |
1ULL << VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD;
@@ -1200,8 +1201,8 @@ vu_set_protocol_features_exec(VuDev *dev, VhostUserMsg
*vmsg)
static bool
vu_get_queue_num_exec(VuDev *dev, VhostUserMsg *vmsg)
{
- DPRINT("Function %s() not implemented yet.\n", __func__);
- return false;
+ vmsg_set_reply_u64(vmsg, dev->max_queues);
+ return true;
}
static bool
--
2.21.0