[libvirt] ARMv7 guest PCI support broken in 3.0.0 onwards

Auger Eric eric.auger at redhat.com
Sun Feb 19 17:54:55 UTC 2017


Hi,

On 18/02/2017 15:09, Andrea Bolognani wrote:
> On Fri, 2017-02-17 at 15:56 +0100, Andrea Bolognani wrote:
>> libvirt is picking GICv3 here because QEMU reports it as a
>> viable emulated GIC; however, as I understand it the
>> emulated GICv3 doesn't have MSI support, and without that
>> PCIe can't work. If you manually switch to GICv2 you should
>> be able to run the guest succesfully.
>>  
>> We should find a way to detect whether the interrupt
>> controller will support PCIe, and fall back to using
>> virtio-mmio when it doesn't. Eric, any ideas about how we
>> could achieve that?
> 
> Actually, we will probably want to do the opposite, eg. pick
> GICv2 over GICv3 if the latter doesn't allow us to use PCIe.

Yes I think the easiest solution is to select the GICv2 + v2m combo to
get the MSI support. This depends on whether the limitations linked to
GICv2 usage are acceptable in your case (max 8 cpus for instance).

Thanks

Eric
> 
> -- 
> Andrea Bolognani / Red Hat / Virtualization
> 




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