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

isaku.yamahata
2024-03-25T21:29:50Z

On Mon, Mar 25, 2024 at 09:43:31PM +1300,
"Huang, Kai" <kai.huang@intel.com> wrote:

>
> > > 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?

Sure, let me update the commit log.
--
Isaku Yamahata <isaku.yamahata@intel.com>