From a3688046995f88c518fa27c45b39ae389260b18d Mon Sep 17 00:00:00 2001 From: Victor Kaplansky Date: Wed, 17 Jan 2018 15:49:25 +0200 Subject: [PATCH] vhost: protect active rings from async ring changes When performing live migration or memory hot-plugging, the changes to the device and vrings made by message handler done independently from vring usage by PMD threads. This causes for example segfaults during live-migration with MQ enable, but in general virtually any request sent by qemu changing the state of device can cause problems. These patches fixes all above issues by adding a spinlock to every vring and requiring message handler to start operation only after ensuring that all PMD threads related to the device are out of critical section accessing the vring data. Each vring has its own lock in order to not create contention between PMD threads of different vrings and to prevent performance degradation by scaling queue pair number. See https://bugzilla.redhat.com/show_bug.cgi?id=1450680 Cc: stable@dpdk.org Signed-off-by: Victor Kaplansky Reviewed-by: Maxime Coquelin Acked-by: Yuanhan Liu --- lib/librte_vhost/vhost.c | 1 + lib/librte_vhost/vhost.h | 6 ++- lib/librte_vhost/vhost_user.c | 70 +++++++++++++++++++++++++++++++++++ lib/librte_vhost/virtio_net.c | 26 +++++++++++-- 4 files changed, 98 insertions(+), 5 deletions(-) diff --git a/lib/librte_vhost/vhost.c b/lib/librte_vhost/vhost.c index 6789ccce5a..1dd9adbc78 100644 --- a/lib/librte_vhost/vhost.c +++ b/lib/librte_vhost/vhost.c @@ -232,6 +232,7 @@ alloc_vring_queue(struct virtio_net *dev, uint32_t vring_idx) dev->virtqueue[vring_idx] = vq; init_vring_queue(dev, vring_idx); + rte_spinlock_init(&vq->access_lock); dev->nr_vring += 1; diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h index b2bf0e833c..e52a9b69c6 100644 --- a/lib/librte_vhost/vhost.h +++ b/lib/librte_vhost/vhost.h @@ -81,12 +81,14 @@ struct vhost_virtqueue { /* Backend value to determine if device should started/stopped */ int backend; + int enabled; + int access_ok; + rte_spinlock_t access_lock; + /* Used to notify the guest (trigger interrupt) */ int callfd; /* Currently unused as polling mode is enabled */ int kickfd; - int enabled; - int access_ok; /* Physical address of used ring, for logging */ uint64_t log_guest_addr; diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c index 0ea28ecee9..1dd1a61b6f 100644 --- a/lib/librte_vhost/vhost_user.c +++ b/lib/librte_vhost/vhost_user.c @@ -1260,12 +1260,47 @@ vhost_user_check_and_alloc_queue_pair(struct virtio_net *dev, VhostUserMsg *msg) return alloc_vring_queue(dev, vring_idx); } +static void +vhost_user_lock_all_queue_pairs(struct virtio_net *dev) +{ + unsigned int i = 0; + unsigned int vq_num = 0; + + while (vq_num < dev->nr_vring) { + struct vhost_virtqueue *vq = dev->virtqueue[i]; + + if (vq) { + rte_spinlock_lock(&vq->access_lock); + vq_num++; + } + i++; + } +} + +static void +vhost_user_unlock_all_queue_pairs(struct virtio_net *dev) +{ + unsigned int i = 0; + unsigned int vq_num = 0; + + while (vq_num < dev->nr_vring) { + struct vhost_virtqueue *vq = dev->virtqueue[i]; + + if (vq) { + rte_spinlock_unlock(&vq->access_lock); + vq_num++; + } + i++; + } +} + int vhost_user_msg_handler(int vid, int fd) { struct virtio_net *dev; struct VhostUserMsg msg; int ret; + int unlock_required = 0; dev = get_device(vid); if (dev == NULL) @@ -1311,6 +1346,38 @@ vhost_user_msg_handler(int vid, int fd) return -1; } + /* + * Note: we don't lock all queues on VHOST_USER_GET_VRING_BASE, + * since it is sent when virtio stops and device is destroyed. + * destroy_device waits for queues to be inactive, so it is safe. + * Otherwise taking the access_lock would cause a dead lock. + */ + switch (msg.request.master) { + case VHOST_USER_SET_FEATURES: + case VHOST_USER_SET_PROTOCOL_FEATURES: + case VHOST_USER_SET_OWNER: + case VHOST_USER_RESET_OWNER: + case VHOST_USER_SET_MEM_TABLE: + case VHOST_USER_SET_LOG_BASE: + case VHOST_USER_SET_LOG_FD: + case VHOST_USER_SET_VRING_NUM: + case VHOST_USER_SET_VRING_ADDR: + case VHOST_USER_SET_VRING_BASE: + case VHOST_USER_SET_VRING_KICK: + case VHOST_USER_SET_VRING_CALL: + case VHOST_USER_SET_VRING_ERR: + case VHOST_USER_SET_VRING_ENABLE: + case VHOST_USER_SEND_RARP: + case VHOST_USER_NET_SET_MTU: + case VHOST_USER_SET_SLAVE_REQ_FD: + vhost_user_lock_all_queue_pairs(dev); + unlock_required = 1; + break; + default: + break; + + } + switch (msg.request.master) { case VHOST_USER_GET_FEATURES: msg.payload.u64 = vhost_user_get_features(dev); @@ -1414,6 +1481,9 @@ vhost_user_msg_handler(int vid, int fd) } + if (unlock_required) + vhost_user_unlock_all_queue_pairs(dev); + if (msg.flags & VHOST_USER_NEED_REPLY) { msg.payload.u64 = !!ret; msg.size = sizeof(msg.payload.u64); diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c index 8ef71ccca7..edfab3ba61 100644 --- a/lib/librte_vhost/virtio_net.c +++ b/lib/librte_vhost/virtio_net.c @@ -15,6 +15,7 @@ #include #include #include +#include #include "iotlb.h" #include "vhost.h" @@ -302,8 +303,11 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id, } vq = dev->virtqueue[queue_id]; + + rte_spinlock_lock(&vq->access_lock); + if (unlikely(vq->enabled == 0)) - return 0; + goto out_access_unlock; if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) vhost_user_iotlb_rd_lock(vq); @@ -389,6 +393,9 @@ out: if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) vhost_user_iotlb_rd_unlock(vq); +out_access_unlock: + rte_spinlock_unlock(&vq->access_lock); + return count; } @@ -621,8 +628,11 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id, } vq = dev->virtqueue[queue_id]; + + rte_spinlock_lock(&vq->access_lock); + if (unlikely(vq->enabled == 0)) - return 0; + goto out_access_unlock; if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) vhost_user_iotlb_rd_lock(vq); @@ -678,6 +688,9 @@ out: if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) vhost_user_iotlb_rd_unlock(vq); +out_access_unlock: + rte_spinlock_unlock(&vq->access_lock); + return pkt_idx; } @@ -1122,9 +1135,13 @@ rte_vhost_dequeue_burst(int vid, uint16_t queue_id, } vq = dev->virtqueue[queue_id]; - if (unlikely(vq->enabled == 0)) + + if (unlikely(rte_spinlock_trylock(&vq->access_lock) == 0)) return 0; + if (unlikely(vq->enabled == 0)) + goto out_access_unlock; + vq->batch_copy_nb_elems = 0; if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) @@ -1293,6 +1310,9 @@ out: if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) vhost_user_iotlb_rd_unlock(vq); +out_access_unlock: + rte_spinlock_unlock(&vq->access_lock); + if (unlikely(rarp_mbuf != NULL)) { /* * Inject it to the head of "pkts" array, so that switch's mac -- 2.20.1