Re: [Qemu-devel] [PATCH 5/5] intel_iommu: do not allow EIM without KVM support

[Peter Xu]

On Fri, Sep 23, 2016 at 11:27:09AM +0200, Paolo Bonzini wrote:
> Since the whole IOMMU feature is new and somewhat experimental, I think
> it's okay to just make EIM the default for >=2.8 machine types if KVM is
> on (using DEFINE_PROP_ON_OFF_AUTO; auto means true if KVM is on and
> false otherwise, and pc-2.7 would set eim=off). It means requiring
> kernel 4.8 by default, but I don't think it's a big deal.

I think the problem is, even we have KVM support for x2apic, we are
still losing QEMU part. And guests with cluster x2apic and >8 vcpus
will not working properly on device interrupts, which can be very
confusing to people (it can boot, but some devices just don't work
properly, and they won't see useful information in guest dmesg).

Thanks,

-- peterx