Re: [PATCH v3 0/8] Alternate Injection: Secure Interrupt Delivery for SEV-SNP Guests - Guest Support

[Ard Biesheuvel]

On Thu, 24 Sep 2026, at 20:34, Melody Wang wrote:
> Hi Ard,
>
> On 9/23/26 1:56 PM, Ard Biesheuvel wrote:
>> This may be a bit of a 'back to the drawing board' remark, but if opting
>> in to this alternate injection scheme can only be done from the EFI firmware
>> before ExitBootServices(), couldn't we wrap all this logic into an OVMF
>> protocol instead? That way, the EFI stub can just invoke it if it exists,
>> and what happens under the hood as a result is entirely under the control of
>> the firmware.
>
...
>
> But if we leave the OVMF to decide for the guest kernel, that is 
> violating the confidential computing principles of the guest being in 
> control.
>

That is not what I am suggesting.

What I would like to see is an abstraction implemented in OVMF that encapsulates
the logic that you are adding here. All the EFI stub would have to do is call
the protocol, nothing more.

After ExitBootServices() is a different matter, and actually, I think doing
the memory acceptance at that point was a mistake, and I'd like to fix that
but that is a separate discussion.

Before ExitBootServices(), we should not be poking MSRs directly. We should
be relying on the abstractions exposed by the firmware.