From eb2b3b18edc3af42f52ca5b3f30aa8bfbd08206a Mon Sep 17 00:00:00 2001 From: Maxime Coquelin Date: Wed, 13 Dec 2017 09:51:09 +0100 Subject: [PATCH 4/6] vhost: destroy unused virtqueues when multiqueue not negotiated 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 Acked-by: Laszlo Ersek Acked-by: Yuanhan Liu (cherry picked from commit e29109323595beb3884da58126ebb3b878cb66f5) Signed-off-by: Maxime Coquelin --- dpdk-17.11/lib/librte_vhost/vhost_user.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/dpdk-17.11/lib/librte_vhost/vhost_user.c b/dpdk-17.11/lib/librte_vhost/vhost_user.c index 471b1612c..1848c8de9 100644 --- a/dpdk-17.11/lib/librte_vhost/vhost_user.c +++ b/dpdk-17.11/lib/librte_vhost/vhost_user.c @@ -216,6 +216,25 @@ 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. + */ + while (dev->nr_vring > 2) { + struct vhost_virtqueue *vq; + + vq = dev->virtqueue[--dev->nr_vring]; + if (!vq) + continue; + + dev->virtqueue[dev->nr_vring] = NULL; + cleanup_vq(vq, 1); + free_vq(vq); + } + } + return 0; } -- 2.14.3