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From: Maxime Coquelin <maxime.coquelin@redhat.com>
To: dev@dpdk.org, yliu@fridaylinux.org, tiwei.bie@intel.com,
	jianfeng.tan@intel.com
Cc: lprosek@redhat.com, lersek@redhat.com,
	Maxime Coquelin <maxime.coquelin@redhat.com>
Subject: [dpdk-dev] [PATCH 4/4] vhost: destroy unused virtqueues when multiqueue not negotiated
Date: Mon,  4 Dec 2017 15:09:00 +0100	[thread overview]
Message-ID: <20171204140900.7906-5-maxime.coquelin@redhat.com> (raw)
In-Reply-To: <20171204140900.7906-1-maxime.coquelin@redhat.com>

QEMU sends VHOST_USER_SET_VRING_CALL requests for all queues
declared in QEMU command line before the guest is started.
It has the effect in DPDK vhost-user backend to allocate vrings
for all queues declared by QEMU.

If the first driver being used does not support multiqueue,
the device never changes to VIRTIO_DEV_RUNNING state as only
the first queue pair is initialized. One driver impacted by
this bug is virtio-net's iPXE driver which does not support
VIRTIO_NET_F_MQ feature.

It is safe to destroy unused virtqueues in SET_FEATURES request
handler, as it is ensured the device is not in running state
at this stage, so virtqueues aren't being processed.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost_user.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index 7d84af3e2..72526e006 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -173,6 +173,7 @@ vhost_user_get_features(struct virtio_net *dev)
 static int
 vhost_user_set_features(struct virtio_net *dev, uint64_t features)
 {
+	int i;
 	uint64_t vhost_features = 0;
 
 	rte_vhost_driver_get_features(dev->ifname, &vhost_features);
@@ -216,6 +217,24 @@ vhost_user_set_features(struct virtio_net *dev, uint64_t features)
 		(dev->features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ? "on" : "off",
 		(dev->features & (1ULL << VIRTIO_F_VERSION_1)) ? "on" : "off");
 
+	if (!(dev->features & (1ULL << VIRTIO_NET_F_MQ))) {
+		/*
+		 * Remove all but first queue pair if MQ hasn't been
+		 * negotiated. This is safe because the device is not
+		 * running at this stage.
+		 */
+		for (i = dev->nr_vring; i > 1; i--) {
+			struct vhost_virtqueue *vq = dev->virtqueue[i];
+
+			if (!vq)
+				continue;
+
+			cleanup_vq(vq, 1);
+			free_vq(vq);
+			dev->nr_vring--;
+		}
+	}
+
 	return 0;
 }
 
-- 
2.14.3

  parent reply	other threads:[~2017-12-04 14:09 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-12-04 14:08 [dpdk-dev] [PATCH 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ " Maxime Coquelin
2017-12-04 14:08 ` [dpdk-dev] [PATCH 1/4] vhost: prevent features to be changed while device is running Maxime Coquelin
2017-12-04 14:17   ` Ladi Prosek
2017-12-04 14:20     ` Maxime Coquelin
2017-12-04 14:08 ` [dpdk-dev] [PATCH 2/4] vhost: propagate VHOST_USER_SET_FEATURES handling error Maxime Coquelin
2017-12-04 14:08 ` [dpdk-dev] [PATCH 3/4] vhost: extract virtqueue cleaning and freeing functions Maxime Coquelin
2017-12-04 14:09 ` Maxime Coquelin [this message]
2017-12-04 14:27 ` [dpdk-dev] [PATCH 0/4] Vhost: fix mq=on but VIRTIO_NET_F_MQ not negotiated Ladi Prosek
2017-12-04 14:48   ` Maxime Coquelin

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