Re: [Qemu-devel] [PATCH V2 1/3] virtio: guard against NULL pfn

[Jason Wang <jasowang@redhat.com>]

On 2017年03月13日 18:18, Paolo Bonzini wrote:
>
> On 13/03/2017 10:55, Cornelia Huck wrote:
>> On Mon, 13 Mar 2017 14:29:41 +0800
>> Jason Wang <jasowang@redhat.com> wrote:
>>
>>> To avoid access stale memory region cache after reset, this patch
>>> check the existence of virtqueue pfn for all exported virtqueue access
>>> helpers before trying to use them.
>>>
>>> Cc: Cornelia Huck <cornelia.huck@de.ibm.com>
>>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>>> Signed-off-by: Jason Wang <jasowang@redhat.com>
>>> ---
>>>   hw/virtio/virtio.c | 21 +++++++++++++++++++++
>>>   1 file changed, 21 insertions(+)
>>>
>>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>>> index efce4b3..76cc81b 100644
>>> --- a/hw/virtio/virtio.c
>>> +++ b/hw/virtio/virtio.c
>>> @@ -322,6 +322,10 @@ static int virtio_queue_empty_rcu(VirtQueue *vq)
>>>           return 0;
>>>       }
>>>
>>> +    if (unlikely(!vq->vring.avail)) {
>>> +        return 0;
>> Shouldn't that rather return !0 (denoting a non-existing queue as
>> empty)?
> Yes, and the check should also go first (before the function can return 0).
>
> Paolo

Yes, will fix in V3.

Thanks