On Mon, Aug 21, 2017 at 10:22:15AM +0800, Lan Tianyu wrote: > On 2017年08月19日 00:38, Eduardo Habkost wrote: > > On Thu, Aug 17, 2017 at 09:37:10AM +0800, Lan Tianyu wrote: > >> On 2017年08月16日 19:21, Paolo Bonzini wrote: > >>> On 16/08/2017 02:22, Lan Tianyu wrote: > >>>> Xen vIOMMU device model will be in Xen hypervisor. Skip vIOMMU > >>>> check for Xen here when vcpu number is more than 255. > >>> > >>> I think you still need to do a check for vIOMMU being enabled. > >> > >> Yes, this will be done in the Xen tool stack and Qemu doesn't have such > >> knowledge. Operations of create, destroy Xen vIOMMU will be done in the > >> Xen tool stack. > > > > Shouldn't we make QEMU have knowledge of the vIOMMU device, then? > > Won't QEMU need to know about it eventually? > > > > Hi Eduardo: > Thanks for your review. > Xen has some guest modes which doesn't use Qemu and we tried to > make Xen vIOMMU framework compatible with all guest modes. So far, we > are adding interrupt remapping function for Xen vIOMMU and find qemu > doesn't need to know Xen vIOMMU. The check of vcpu number > 255 here > will be done in Xen side and so skip the check in Qemu to avoid blocking > Xen creating >255 vcpus. > We may make Qemu have knowledge of the vIOMMU device if it's > necessary when adding new function.
I was expecting it to go through the PC tree, but I will queue it on x86-next instead. -- Eduardo
