Re: [RFC PATCH v3 01/27] x86/apic: Propagate APIC_SPIV writes to hv for Secure AVIC

[Tom Lendacky]

On 7/10/26 10:02, Naveen N Rao wrote:
> On Thu, Jul 09, 2026 at 07:03:49PM -0700, Borislav Petkov wrote:
>> On Wed, Jul 08, 2026 at 12:01:59PM +0530, Naveen N Rao (AMD) wrote:
>>> From: Neeraj Upadhyay <Neeraj.Upadhyay@xxxxxxx>
>>>
>>> Hypervisor needs to be aware of the VAPIC's APIC_SPIV state for
>>> LVT masking/unmasking. So, propagate the guest's APIC_SPIV
>>> writes to the hypervisor.
>>>
>>> Fixes: c822f58a4fab ("x86/apic: Populate .read()/.write() callbacks of Secure AVIC driver")
>>
>> What is that patch actually fixing?
> 
> Guest doesn't boot without this change.

This sounds like something that should be submitted outside of this
series, especially since this is an RFC series.

Thanks,
Tom

> 
>>
>> Does it need to go to stable?
> 
> Yes. I will tag stable on this.
> 
>>
>> SPIV needs to be masked and unmasked by the guest?
>>
>> Doesn't seem too earth-shattering to me but what do I know...
> 
> APIC_SPIV has a bit to (soft-)disable the APIC. It starts off disabled 
> and the kernel has to write to it to enable the APIC. If writes from the 
> guest are not propagated to KVM, KVM does not deliver interrupts to the 
> guest since the APIC is disabled as far as it is concerned.
> 
> I will update the commit log with these details.
> 
>>
>>> Signed-off-by: Neeraj Upadhyay <Neeraj.Upadhyay@xxxxxxx>
>>
>> verify_tags: WARNING: Sender ["Naveen N Rao (AMD)" <naveen@xxxxxxxxxx>] hasn't signed off on the patch!
>>
>> When you send someone else's patch, you *must* put you SOB after hers/his.
> 
> I was genuinely unaware of this. Just so I get this right:
> - Add just the 'Sob:' for patches from others that I post un-modified 
>   (without a Co-developed-by: tag)
> - Add 'Co-developed-by:' if I make any changes to the patch (commit log 
>   included?)
> 
> 
> Thanks,
> Naveen
>