Re: [PATCH v19 037/130] KVM: TDX: Make KVM_CAP_MAX_VCPUS backend specific

Huang, Kai
2024-03-25T08:43:52Z

>> Currently, the KVM x86 always reports KVM_MAX_VCPUS for all VMs but doesn't
>> allow to enable KVM_CAP_MAX_VCPUS to configure the number of maximum vcpus
> maximum number of vcpus
>> on VM-basis.
>>
>> Add "per-VM maximum vcpus" to KVM x86/TDX to accommodate TDX's needs.
>>
>> The userspace-configured value then can be verified when KVM is actually
> used
>> creating the TDX guest.
>> "

I think we still have two options regarding to how 'max_vcpus' is
handled in ioctl() to do TDH.MNG.INIT:

1) Just use the 'max_vcpus' done in KVM_ENABLE_CAP(KVM_CAP_MAX_VCPUS),
2) Still pass the 'max_vcpus' as input, but KVM verifies it against the
value that is saved in KVM_ENABLE_CAP(KVM_CAP_MAX_VCPUS).

2) seems unnecessary, so I don't have objection to use 1). But it seems
we could still mention it in the changelog in that patch?