Re: [EXTERNAL] [PATCH] x86/io-apic: fix directed EOI when using AMd-Vi interrupt remapping

[David Woodhouse <dwmw2@xxxxxxxxxxxxx>]

On Mon, 2024-10-21 at 12:53 +0100, Andrew Cooper wrote:
> 
> > I don't quite follow how you need a sentinel value. How could you ever
> > *not* know it, given that you have to write it to the RTE?
> > 
> > (And you should *also* just use the pin# like Linux does, as I said).
> 
> Because Xen is insane and, for non-x2APIC cases, sets the system up
> normally and the turns the IOMMU on late.
> 
> This really does need deleting, and everything merging into the early path.

Don't you still have to mask the interrupts when enabling the IOMMU and
then re-enable them by writing the new values to the RTE once remapping
is turned on? So at any given moment, surely it's still the case that
you know what was written to the RTE?

But OK, i don't really want to know... :)

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