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Date: Wed, 29 Jun 2016 15:44:36 +0800
From: Peter Xu <peterx@redhat.com>
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Subject: Re: [Qemu-devel] Question about qtest and IOMMU
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Jan Kiszka <jan.kiszka@web.de>, QEMU Devel Mailing List <qemu-devel@nongnu.org>, Peter Maydell <peter.maydell@linaro.org>, "Michael S. Tsirkin" <mst@redhat.com>, Valentine Sinitsyn <valentine.sinitsyn@gmail.com>, David kiarie <davidkiarie4@gmail.com>, John Snow <jsnow@redhat.com>

On Wed, Jun 29, 2016 at 09:08:29AM +0200, Paolo Bonzini wrote:
> 
> 
> On 29/06/2016 08:36, Jan Kiszka wrote:
> > On 2016-06-29 08:32, Peter Xu wrote:
> >> Hi, all,
> >>
> >> I am thinking about whether it's possible to write up a unit test
> >> program for emulated IOMMUs (of course, Intel IOMMU would be the first
> >> one). This can provide us the chance to do quick functional regression
> >> tests for IOMMU just like other devices, as well as customized test
> >> sequences which is hard to do in real guests (e.g., specific cache
> >> invalidations, error injections), etc..
> >>
> >> I see that current qtest framework cannot support well on testing
> >> IOMMUs. For DMA remapping, things would be quite smooth. The problem
> >> is that, we still do not have a complete test framework on the
> >> interrupts. E.g., currently qtest is still an acceleration type, in
> >> which we have no vCPUs, as well as interrupt chips like APICs (please
> >> correct me if I am wrong).
> 
> qtest does have VCPUs, they just run a dummy loop.  You do have an APIC
> too, but reading it doesn't work because cpu_get_current_apic() returns
> NULL.

Right, thanks to point out.

> 
> You can use kvm-unit-tests if qtest is not flexible enough.  It's
> probably the simplest thing to do if you also want to test kernel LAPIC
> and split irqchip operation.

Will have a look. Thanks Paolo. :)

-- peterx