On Tue, Apr 28, 2015 at 10:04:15AM +0200, Cornelia Huck wrote: > On Tue, 28 Apr 2015 09:14:07 +0200 > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > On Tue, Apr 28, 2015 at 02:13:20PM +0800, Jason Wang wrote: > > > > > > > > > On Tue, Apr 28, 2015 at 1:13 PM, Michael S. Tsirkin <m...@redhat.com> > > > wrote: > > > >On Tue, Apr 28, 2015 at 11:14:04AM +0800, Jason Wang wrote: > > > >> On Mon, Apr 27, 2015 at 7:05 PM, Michael S. Tsirkin > > > >><m...@redhat.com> wrote: > > > >> >On Thu, Apr 23, 2015 at 02:21:41PM +0800, Jason Wang wrote: > > > >> >> This patch introduces a bus specific queue limitation. It will be > > > >> >> useful for increasing the limit for one of the bus without > > > >>disturbing > > > >> >> other buses. > > > >> >> Cc: Michael S. Tsirkin <m...@redhat.com> > > > >> >> Cc: Alexander Graf <ag...@suse.de> > > > >> >> Cc: Richard Henderson <r...@twiddle.net> > > > >> >> Cc: Cornelia Huck <cornelia.h...@de.ibm.com> > > > >> >> Cc: Christian Borntraeger <borntrae...@de.ibm.com> > > > >> >> Cc: Paolo Bonzini <pbonz...@redhat.com> > > > >> >> Signed-off-by: Jason Wang <jasow...@redhat.com> > > > >> >> Reviewed-by: Cornelia Huck <cornelia.h...@de.ibm.com> > > > >> > > > > >> >Is this still needed if you drop the attempt to > > > >> >keep the limit around for old machine types? > > > >> If we agree to drop, we probably need transport specific macro. > > > > > > > >You mean just rename VIRTIO_PCI_QUEUE_MAX to VIRTIO_QUEUE_MAX? > > > >Fine, why not. > > > > > > I mean keeping VIRTIO_PCI_QUEUE_MAX for pci only and just increase pci > > > limit. And introduce e.g VIRTIO_PCI_QUEUE_CCW for ccw and keep it as 64. > > > Since to my understanding, it's not safe to increase the limit for all > > > other > > > transports which was pointed out by Cornelia in V1: > > > http://permalink.gmane.org/gmane.comp.emulators.qemu/318245. > > > > I think all you need is add a check to CCW_CMD_SET_IND: > > limit to 64 for legacy interrupts only. > > It isn't that easy. > > What is easy is to add a check to the guest driver that fails setup for > devices with more than 64 queues not using adapter interrupts. > > On the host side, we're lacking information when interpreting > CCW_CMD_SET_IND (the command does not contain a queue count, and the > actual number of virtqueues is not readily available.)
Why isn't it available? All devices call virtio_add_queue as appropriate. Just fail legacy adaptors. > We also can't > fence off when setting up the vqs, as this happens before we know which > kind of indicators the guest wants to use. > > More importantly, we haven't even speced what we want to do in this > case. Do we want to reject SET_IND for devices with more than 64 > queues? (Probably yes.) > > All this involves more work, and I'd prefer to do Jason's changes > instead as this gives us some more time to figure this out properly. > > And we haven't even considered s390-virtio yet, which I really want to > touch as little as possible :) Well this patch does touch it anyway :) For s390 just check and fail at init if you like. -- MST
