Re: [RFC v2 14/17] x86/apic: Add kexec support for Secure AVIC

Neeraj Upadhyay
2025-04-01T10:35:35Z

On 3/21/2025 9:18 PM, Thomas Gleixner wrote:
> On Wed, Feb 26 2025 at 14:35, Neeraj Upadhyay wrote:
>>
>> +/*
>> + * Unregister GPA of the Secure AVIC backing page.
>> + *
>> + * @apic_id: APIC ID of the vCPU. Use -1ULL for the current vCPU
>
> Yes, -1ULL is really a sensible value - NOT. Ever thought about
> signed/unsigned?
>

In table "Table 7: List of Supported Non-Automatic Events" of GHCB spec [1],
0xffff_ffff_ffff_ffff is used for Secure AVIC GHCB event

"RAX will have the APIC ID of the target vCPU or 0xffff_ffff_ffff_ffff
for the vCPU doing the call"

I am using -1ULL for that here.

[1] https://www.amd.com/content/dam/amd/en/documents/epyc-technical-docs/specifications/56421.pdf

>> + * doing the call.
>
> How would this function ever make sense to be invoked from a remote CPU?
>

I will update the interface in next version. Remote CPU interface is not used.

>> + * On success, returns previously registered GPA of the Secure AVIC
>> + * backing page in gpa arg.
>
> Please use proper kernel-doc formatting and not some made up thing which
> looks like it.
>

Ok. I will update this.

- Neeraj

> Thanks,
>
> tglx