[PATCH 5.13 039/127] virtio: Protect vqs list access

Sasha Levin
2021-08-24T16:58:07Z

From: Parav Pandit <parav@nvidia.com>

[ Upstream commit 0e566c8f0f2e8325e35f6f97e13cde5356b41814 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/virtio/virtio.c | 1 +
drivers/virtio/virtio_ring.c | 8 ++++++++
include/linux/virtio.h | 1 +
3 files changed, 10 insertions(+)

diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index 4b15c00c0a0a..49984d2cba24 100644
--- 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 71e16b53e9c1..6b7aa26c5384 100644
--- a/drivers/virtio/virtio_ring.c
+++ b/drivers/virtio/virtio_ring.c
@@ -1668,7 +1668,9 @@ 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:
@@ -2126,7 +2128,9 @@ 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;
}
EXPORT_SYMBOL_GPL(__vring_new_virtqueue);
@@ -2210,7 +2214,9 @@ void vring_del_virtqueue(struct virtqueue *_vq)
}
if (!vq->packed_ring)
kfree(vq->split.desc_state);
+ spin_lock(&vq->vq.vdev->vqs_list_lock);
list_del(&_vq->list);
+ spin_unlock(&vq->vq.vdev->vqs_list_lock);
kfree(vq);
}
EXPORT_SYMBOL_GPL(vring_del_virtqueue);
@@ -2274,10 +2280,12 @@ 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);
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 b1894e0323fa..41edbc01ffa4 100644
--- 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;
--
2.30.2