RE: [PATCH 3/4] virtio: Protect vqs list access
> From: Michael S. Tsirkin > Sent: Sunday, July 18, 2021 2:11 AM > > On Sat, Jul 17, 2021 at 10:42:57AM +0300, Parav Pandit wrote: > > 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 > > --- > > 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..a0d81e35ec4b 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(>vqs); > > + rwlock_init(>vqs_list_lock); > > > > /* > > * device_add() causes the bus infrastructure to look for a matching > > Let's just use a simple spinlock. I don't think we are worried about scaling > the > breaking of devices to multiple CPUs. > It wasn't the scaling, just wanted to have the clarity on list access. But I realized that rwlock is bigger size too. So yeah, will simplify to spinlock in v2. ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
Re: [PATCH 3/4] virtio: Protect vqs list access
On Sat, Jul 17, 2021 at 10:42:57AM +0300, Parav Pandit wrote: > 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 > --- > 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..a0d81e35ec4b 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(>vqs); > + rwlock_init(>vqs_list_lock); > > /* >* device_add() causes the bus infrastructure to look for a matching Let's just use a simple spinlock. I don't think we are worried about scaling the breaking of devices to multiple CPUs. > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index d2e1a7a21171..66a91dec39d9 100644 > --- 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); > } > > + write_lock(>vqs_list_lock); > list_add_tail(>vq.list, >vqs); > + write_unlock(>vqs_list_lock); > return >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)); > > + write_lock(>vqs_list_lock); > list_add_tail(>vq.list, >vqs); > + write_unlock(>vqs_list_lock); > return >vq; > > err_extra: > @@ -2291,7 +2295,9 @@ void vring_del_virtqueue(struct virtqueue *_vq) > { > struct vring_virtqueue *vq = to_vvq(_vq); > > + write_lock(>vq.vdev->vqs_list_lock); > list_del(&_vq->list); > + write_unlock(>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; > > + read_lock(>vqs_list_lock); > list_for_each_entry(_vq, >vqs, list) { > struct vring_virtqueue *vq = to_vvq(_vq); > > /* Pairs with READ_ONCE() in virtqueue_is_broken(). */ > smp_store_release(>broken, true); > } > + read_unlock(>vqs_list_lock); > } > EXPORT_SYMBOL_GPL(virtio_break_device); > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index b1894e0323fa..1cf77d480ef3 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -115,6 +115,7 @@ struct virtio_device { > const struct virtio_config_ops *config; > const struct vringh_config_ops *vringh_config; > struct list_head vqs; > + rwlock_t vqs_list_lock; > u64 features; > void *priv; > }; > -- > 2.27.0 ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
[PATCH 3/4] 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 --- 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..a0d81e35ec4b 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(>vqs); + rwlock_init(>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 d2e1a7a21171..66a91dec39d9 100644 --- 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); } + write_lock(>vqs_list_lock); list_add_tail(>vq.list, >vqs); + write_unlock(>vqs_list_lock); return >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)); + write_lock(>vqs_list_lock); list_add_tail(>vq.list, >vqs); + write_unlock(>vqs_list_lock); return >vq; err_extra: @@ -2291,7 +2295,9 @@ void vring_del_virtqueue(struct virtqueue *_vq) { struct vring_virtqueue *vq = to_vvq(_vq); + write_lock(>vq.vdev->vqs_list_lock); list_del(&_vq->list); + write_unlock(>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; + read_lock(>vqs_list_lock); list_for_each_entry(_vq, >vqs, list) { struct vring_virtqueue *vq = to_vvq(_vq); /* Pairs with READ_ONCE() in virtqueue_is_broken(). */ smp_store_release(>broken, true); } + read_unlock(>vqs_list_lock); } EXPORT_SYMBOL_GPL(virtio_break_device); diff --git a/include/linux/virtio.h b/include/linux/virtio.h index b1894e0323fa..1cf77d480ef3 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -115,6 +115,7 @@ struct virtio_device { const struct virtio_config_ops *config; const struct vringh_config_ops *vringh_config; struct list_head vqs; + rwlock_t vqs_list_lock; u64 features; void *priv; }; -- 2.27.0 ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization