Re: [PATCH v5 1/3] KVM: x86: Refactor suppress EOI broadcast logic

[Khushit Shah]

> On 16 Jan 2026, at 2:31 PM, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
> 
> But KVM *will* notify listeners, surely? When the guest issues the EOI
> via the I/O APIC EOIR register.
> 
> For that commit to have made any difference, Xen *has* to have been
> buggy, enabling directed EOI in the local APIC despite the I/O APIC not
> having the required support. Thus interrupts never got EOI'd at all,
> and sure, the notifiers didn't get called.

You are describing 
0bcc3fb95b97 ("KVM: lapic: stop advertising DIRECTED_EOI when in-kernel IOAPIC is in use”)
Since then I guess this issue should have been fixed?!  As
c806a6ad35bf ("KVM: x86: call irq notifiers with directed EOI”)  was much earlier.

> On 16 Jan 2026, at 2:31 PM, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
> 
> If you're concerned about what to backport to stable, then arguably
> it's *only* KVM_X2APIC_DISABLE_SUPPRESS_EOI_BROADCAST which should be
> backported, as that's the bug, and _ENABLE_ is a new feature?

I think neither DISABLE or ENABLE is a new feature at least for split IRQCHIP.
It’s just giving a way to user-space to fix a bug in a way they like, because that’s how
it should have been from the beginning.