Re: [Qemu-devel] [virtio] qemu vs vhost virtqueue consumer

[Catalin Vasile]

Awesome.
Thanks

On Tue, Apr 7, 2015 at 11:51 AM, Greg Kurz <address@hidden> wrote:
> On Tue, 7 Apr 2015 11:10:07 +0300
> Catalin Vasile <address@hidden> wrote:
>
>> I am using the virtio-net vhost-net model to make another virtio/vhost 
>> solution.
>> I can't seem to find how does one make a virtqueue to only be consumed
>> by vhost when adding notifiers to vhost.
>> virtio_add_queue() seems to always ask for a valid handle for qemu,
>> and I don't see any disable function primitives called in either vhost
>> or virtio part in qemu.
>> I then thought the qemu part checks a flag every time a message
>> appears, and it stops it from popping data from the virtqueue, but I
>> don't see that either.
>> How does the virtio/vhost-net solution make sure qemu doesn't consume
>> data from a virtqueue destined for vhost?
>>
>
> The idea behind vhost is we want to avoid QEMU to be involved when data
> is being copied to/from the guest:  "adding notifiers to vhost" basically
> means that MMIO will be redirected to vhost instead of QEMU. In other
> words, QEMU cannot consume data because it is simply not notified at all
> in this case.
>
> Cheers.
>
> --
> Greg
>
>
>
>