Re: [PATCH-for-9.0 v2 06/19] hw/pci/msi: Restrict xen_is_pirq_msi() call to Xen

[David Woodhouse]

On Tue, 2023-11-14 at 10:44 -0500, David Woodhouse wrote:
> 
> I believe that if you push your branch to a gitlab tree with the
> right CI variables defined, it'll run all the CI? And I *hope* it
> fails with this patch. It's precisely the kind of thing I was
> *intending* to catch with the testing!

So it doesn't fail. Because virtio-net-pci doesn't use MSI, we need to
test with E1000E or something like that. And actually I'm not 100%
convinced the avocado tests are even running in the gitlab CI.

And also, if I test it manually... it doesn't fail because you didn't
break it :)

You didn't break the xen_evtchn_snoop_msi() call; that still works.

What you were changing is the part which makes msi_is_masked() lie and
unconditionally return false when it's mapped to a Xen PIRQ. And
actually, even in the Xen-emulation case, xen_is_pirq_msi() is always
returning zero. So your patch isn't changing anything.

It *does*, however, make hw/pci/msi.c do this exactly the same way as
hw/pci/msix.c does. That one does check xen_enabled() first.

I need to double-check whether the msi{x,}_is_masked() checks ought to
be doing the same for Xen-emu as they do on real Xen. That whole thing
is a complete abomination. But that isn't your problem. For your patch,

Reviewed-by: David Woodhouse <dwmw@amazon.co.uk>

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