virtio: Protect vqs list access

VQs may be accessed to mark the device broken while they are
created/destroyed. Hence protect the access to the vqs list.

Fixes: e2dcdfe95c0b ("virtio: virtio_break_device() to mark all virtqueues broken.")
Signed-off-by: Parav Pandit <parav@nvidia.com>
Link: https://lore.kernel.org/r/20210721142648.1525924-4-parav@nvidia.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 4b15c00c0a0afc5de99b1af79cd277553a9322e1..49984d2cba2467ba6855c49e394a7b653cd3ddbe 100644 (file)
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -355,6 +355,7 @@ int register_virtio_device(struct virtio_device *dev)
        virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
 
        INIT_LIST_HEAD(&dev->vqs);
+       spin_lock_init(&dev->vqs_list_lock);
 
        /*
         * device_add() causes the bus infrastructure to look for a matching

diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c
index d5934c2e5a899870c5b5190cba3ce0979682b844..c2aaa0eff6df1869b9786fd6aeb12e5620fe7a83 100644 (file)
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1755,7 +1755,9 @@ static struct virtqueue *vring_create_virtqueue_packed(
                        cpu_to_le16(vq->packed.event_flags_shadow);
        }
 
+       spin_lock(&vdev->vqs_list_lock);
        list_add_tail(&vq->vq.list, &vdev->vqs);
+       spin_unlock(&vdev->vqs_list_lock);
        return &vq->vq;
 
 err_desc_extra:
@@ -2229,7 +2231,9 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index,
        memset(vq->split.desc_state, 0, vring.num *
                        sizeof(struct vring_desc_state_split));
 
+       spin_lock(&vdev->vqs_list_lock);
        list_add_tail(&vq->vq.list, &vdev->vqs);
+       spin_unlock(&vdev->vqs_list_lock);
        return &vq->vq;
 
 err_extra:
@@ -2291,7 +2295,9 @@ void vring_del_virtqueue(struct virtqueue *_vq)
 {
        struct vring_virtqueue *vq = to_vvq(_vq);
 
+       spin_lock(&vq->vq.vdev->vqs_list_lock);
        list_del(&_vq->list);
+       spin_unlock(&vq->vq.vdev->vqs_list_lock);
 
        if (vq->we_own_ring) {
                if (vq->packed_ring) {
@@ -2386,12 +2392,14 @@ void virtio_break_device(struct virtio_device *dev)
 {
        struct virtqueue *_vq;
 
+       spin_lock(&dev->vqs_list_lock);
        list_for_each_entry(_vq, &dev->vqs, list) {
                struct vring_virtqueue *vq = to_vvq(_vq);
 
                /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
                WRITE_ONCE(vq->broken, true);
        }
+       spin_unlock(&dev->vqs_list_lock);
 }
 EXPORT_SYMBOL_GPL(virtio_break_device);
 

diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index b1894e0323fae45163eb2b10091d96fbc9f78401..41edbc01ffa4039524d5519caaa2f18e5884ca65 100644 (file)
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -110,6 +110,7 @@ struct virtio_device {
        bool config_enabled;
        bool config_change_pending;
        spinlock_t config_lock;
+       spinlock_t vqs_list_lock; /* Protects VQs list access */
        struct device dev;
        struct virtio_device_id id;
        const struct virtio_config_ops *config;