Re: [dpdk-dev] [PATCH v8 3/8] vhost: vring queue setup for multiple queue support

[Yuanhan Liu <yuanhan.liu@linux.intel.com>]

On Tue, Oct 27, 2015 at 11:17:16AM +0200, Michael S. Tsirkin wrote:
> On Tue, Oct 27, 2015 at 03:20:40PM +0900, Tetsuya Mukawa wrote:
> > On 2015/10/26 14:42, Yuanhan Liu wrote:
> > > On Mon, Oct 26, 2015 at 02:24:08PM +0900, Tetsuya Mukawa wrote:
> > >> On 2015/10/22 21:35, Yuanhan Liu wrote:
> > > ...
> > >>> @@ -292,13 +300,13 @@ user_get_vring_base(struct vhost_device_ctx ctx,
> > >>>  	 * sent and only sent in vhost_vring_stop.
> > >>>  	 * TODO: cleanup the vring, it isn't usable since here.
> > >>>  	 */
> > >>> -	if ((dev->virtqueue[VIRTIO_RXQ]->kickfd) >= 0) {
> > >>> -		close(dev->virtqueue[VIRTIO_RXQ]->kickfd);
> > >>> -		dev->virtqueue[VIRTIO_RXQ]->kickfd = -1;
> > >>> +	if ((dev->virtqueue[state->index]->kickfd + VIRTIO_RXQ) >= 0) {
> > >>> +		close(dev->virtqueue[state->index + VIRTIO_RXQ]->kickfd);
> > >>> +		dev->virtqueue[state->index + VIRTIO_RXQ]->kickfd = -1;
> > >>>  	}
> > >> Hi Yuanhan,
> > >>
> > >> Please let me make sure whether below is correct.
> > >>     if ((dev->virtqueue[state->index]->kickfd + VIRTIO_RXQ) >= 0) {
> > >>
> > >>> -	if ((dev->virtqueue[VIRTIO_TXQ]->kickfd) >= 0) {
> > >>> -		close(dev->virtqueue[VIRTIO_TXQ]->kickfd);
> > >>> -		dev->virtqueue[VIRTIO_TXQ]->kickfd = -1;
> > >>> +	if ((dev->virtqueue[state->index]->kickfd + VIRTIO_TXQ) >= 0) {
> > >>> +		close(dev->virtqueue[state->index + VIRTIO_TXQ]->kickfd);
> > >>> +		dev->virtqueue[state->index + VIRTIO_TXQ]->kickfd = -1;
> > >> Also, same question here.
> > > Oops, silly typos... Thanks for catching it out!
> > >
> > > Here is an update patch (Thomas, please let me know if you prefer me
> > > to send the whole patchset for you to apply):
> > 
> > Hi Yuanhan,
> > 
> > I may miss one more issue here.
> > Could you please see below patch I've submitted today?
> > (I may find a similar issue, so I've fixed it also in below patch.)
> >  
> > - http://dpdk.org/dev/patchwork/patch/8038/
> >  
> > Thanks,
> > Tetsuya
> 
> Looking at that, at least when MQ is enabled, please don't key
> stopping queues off GET_VRING_BASE.

Yes, that's only a workaround. I guess it has been there for quite a
while, maybe at the time qemu doesn't send RESET_OWNER message.

> There are ENABLE/DISABLE messages for that.

That's something new, though I have plan to use them instead, we still
need to make sure our code work with old qemu, without ENABLE/DISABLE
messages.

And I will think more while enabling live migration: I should have
more time to address issues like this at that time.

> Generally guys, don't take whatever QEMU happens to do for
> granted! Look at the protocol spec under doc/specs directory,
> if you are making more assumptions you must document them!

Indeed. And we will try to address them bit by bit in future.

	--yliu