Re: [PATCH v5 2/3] KVM: x86/ioapic: Implement support for I/O APIC version 0x20 with EOIR

[Khushit Shah]

> On 2 Jan 2026, at 9:47 PM, David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
> 
> On Mon, 2025-12-29 at 15:57 +0000, Khushit Shah wrote:
>> 
>> 
>> We can't use `_respect_` here because in QUIRKED mode with in-kernel IRQCHIP:
>> 
>>   advertise = false  (version 0x11 advertised, no EOIR register)
>>   respect   = true   (legacy quirk: honor SPIV bit even if not advertised)
> 
> Oh wow, right. Since commit 0bcc3fb95b97a ("KVM: lapic: stop
> advertising DIRECTED_EOI when in-kernel IOAPIC is in use"), KVM with
> the in-kernel I/O APIC will *not* advertise the EOI suppression in the
> local APIC version register… but does actually honour the DIRECTED_EOI
> bit if the guest sets it anyway.
> 
> While with a userspace I/O APIC, KVM *will* advertise it, but not
> honour it.
> 
> Yay.
> 
> So yes, your code is the best way to do it. Sorry for the noise.


Thanks, for the review!