Re: [PATCH v11 25/40] virtio: allow to unbreak/break virtqueue individually

Jason Wang
2022-07-04T03:47:48Z

在 2022/7/1 17:36, Jason Wang 写道:
>
> 在 2022/7/1 14:31, Michael S. Tsirkin 写道:
>> On Wed, Jun 29, 2022 at 02:56:41PM +0800, Xuan Zhuo wrote:
>>> This patch allows the new introduced
>>> __virtqueue_break()/__virtqueue_unbreak() to break/unbreak the
>>> virtqueue.
>>>
>>> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
>> I wonder how this interacts with the hardening patches.
>> Jason?
>
>
> Consider we've marked it as broken, I think we don't need to care
> about the hardening in this series. Just make it work without hardening.
>
> And I will handle vq reset when rework the IRQ hardening.
>
> Thanks

Rethink of this, I think Xuan's code should be fine. We know we will
have another rework.

Thanks

>
>
>>
>>> ---
>>>   drivers/virtio/virtio_ring.c | 24 ++++++++++++++++++++++++
>>>   include/linux/virtio.h       |  3 +++
>>>   2 files changed, 27 insertions(+)
>>>
>>> diff --git a/drivers/virtio/virtio_ring.c
>>> b/drivers/virtio/virtio_ring.c
>>> index 5ec43607cc15..7b02be7fce67 100644
>>> --- a/drivers/virtio/virtio_ring.c
>>> +++ b/drivers/virtio/virtio_ring.c
>>> @@ -2744,6 +2744,30 @@ unsigned int virtqueue_get_vring_size(struct
>>> virtqueue *_vq)
>>>   }
>>>   EXPORT_SYMBOL_GPL(virtqueue_get_vring_size);
>>>   +/*
>>> + * This function should only be called by the core, not directly by
>>> the driver.
>>> + */
>>> +void __virtqueue_break(struct virtqueue *_vq)
>>> +{
>>> +    struct vring_virtqueue *vq = to_vvq(_vq);
>>> +
>>> +    /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
>>> +    WRITE_ONCE(vq->broken, true);
>>> +}
>>> +EXPORT_SYMBOL_GPL(__virtqueue_break);
>>> +
>>> +/*
>>> + * This function should only be called by the core, not directly by
>>> the driver.
>>> + */
>>> +void __virtqueue_unbreak(struct virtqueue *_vq)
>>> +{
>>> +    struct vring_virtqueue *vq = to_vvq(_vq);
>>> +
>>> +    /* Pairs with READ_ONCE() in virtqueue_is_broken(). */
>>> +    WRITE_ONCE(vq->broken, false);
>>> +}
>> I don't think these "Pairs" comments have any value.
>>
>>
>>> +EXPORT_SYMBOL_GPL(__virtqueue_unbreak);
>>> +
>>>   bool virtqueue_is_broken(struct virtqueue *_vq)
>>>   {
>>>       struct vring_virtqueue *vq = to_vvq(_vq);
>>> diff --git a/include/linux/virtio.h b/include/linux/virtio.h
>>> index 1272566adec6..dc474a0d48d1 100644
>>> --- a/include/linux/virtio.h
>>> +++ b/include/linux/virtio.h
>>> @@ -138,6 +138,9 @@ bool is_virtio_device(struct device *dev);
>>>   void virtio_break_device(struct virtio_device *dev);
>>>   void __virtio_unbreak_device(struct virtio_device *dev);
>>>   +void __virtqueue_break(struct virtqueue *_vq);
>>> +void __virtqueue_unbreak(struct virtqueue *_vq);
>>> +
>>>   void virtio_config_changed(struct virtio_device *dev);
>>>   #ifdef CONFIG_PM_SLEEP
>>>   int virtio_device_freeze(struct virtio_device *dev);
>>> --
>>> 2.31.0