Re: [PATCH] KVM: SVM: Do not terminate SEV-ES guests on GHCB validation failure

[Tom Lendacky]

On 5/14/21 6:06 PM, Peter Gonda wrote:
> On Fri, May 14, 2021 at 1:22 PM Tom Lendacky <thomas.lendacky@xxxxxxx> wrote:
>>
>> Currently, an SEV-ES guest is terminated if the validation of the VMGEXIT
>> exit code and parameters fail. Since the VMGEXIT instruction can be issued
>> from userspace, even though userspace (likely) can't update the GHCB,
>> don't allow userspace to be able to kill the guest.
>>
>> Return a #GP request through the GHCB when validation fails, rather than
>> terminating the guest.
> 
> Is this a gap in the spec? I don't see anything that details what
> should happen if the correct fields for NAE are not set in the first
> couple paragraphs of section 4 'GHCB Protocol'.

No, I don't think the spec needs to spell out everything like this. The
hypervisor is free to determine its course of action in this case.

I suppose the spec could suggest a course of action, but I don't think the
spec should require a specific course of action.

Thanks,
Tom

>