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Re: [PATCH] x86/vlapic: Don't change ICR on x2APIC SELF_IPI write
- To: xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Christian Ludloff <ludloff@xxxxxxxxx>
- Date: Mon, 26 Oct 2026 21:43:44 +0100
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On Tue, Oct 20, 2026 at 1:40 AM Christian Ludloff <ludloff@xxxxxxxxx> wrote:
>
> > It looks like it's a behavioural difference between Core and Atom.
> > Core modify ICR, while Atom do not.
>
> For Core there might be more nuance yet.
>
> I seem to have an ICL result for "does not".
>
> And I seem to have two SKL machs (same
> stepping, same ucode) that... disagree with
> each other. Some sort of config thing...?
>
> Maybe Intel can explain.
>
> I consider "does not" the cleaner behavior,
> unless a compelling explanation is offered.
Andy – as discussed off list, both were cases
of a sneaky HV put in place by the mach FW.
So for the thread subject we got closure.
Sorry it took a little longer to track down – in
the process the authors of the FW stack did
receive a belated dose of Spectre fallout.
--
C.
|
