Re: [PATCH v11 017/113] KVM: Support KVM_CAP_MAX_VCPUS for KVM_ENABLE_CAP

[Isaku Yamahata]

On Fri, Jan 13, 2023 at 02:55:07PM +0200,
Zhi Wang <zhi.wang.linux@xxxxxxxxx> wrote:

> On Thu, 12 Jan 2023 08:31:25 -0800
> isaku.yamahata@xxxxxxxxx wrote:
> 
> > From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> > 
> > TDX attestation includes the maximum number of vcpu that the guest can
> > accommodate.  For that, the maximum number of vcpu needs to be specified
> > instead of constant, KVM_MAX_VCPUS.  Make KVM_ENABLE_CAP support
> > KVM_CAP_MAX_VCPUS.
> > 
> > Suggested-by: Sagi Shahar <sagis@xxxxxxxxxx>
> > Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> > ---
> >  virt/kvm/kvm_main.c | 20 ++++++++++++++++++++
> >  1 file changed, 20 insertions(+)
> > 
> > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> > index a235b628b32f..1cfa7da92ad0 100644
> > --- a/virt/kvm/kvm_main.c
> > +++ b/virt/kvm/kvm_main.c
> > @@ -4945,7 +4945,27 @@ static int kvm_vm_ioctl_enable_cap_generic(struct
> > kvm *kvm, }
> >  
> >  		mutex_unlock(&kvm->slots_lock);
> > +		return r;
> > +	}
> > +	case KVM_CAP_MAX_VCPUS: {
> 
> Better mention the KVM_CAP_MAX_VCPUS defined in XXX patch in the comments.

This already exists as KVM api and documented in Documentation/virt/kvm/api.rst
to get the possible maximum number of vcpus.
This patch make it settable.
-- 
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>