Re: [PATCH RFC 01/39] KVM: x86: fix Xen hypercall page msr handling

[Paolo Bonzini]

On 22/02/19 02:30, Sean Christopherson wrote:
> 	if (kvm_advertise_kvm()) {
> 		if (<handle kvm msr>)
> 			return ...;
> 	} else if (kvm_advertise_hyperv()) {
> 		if (<handle hyperv msr>)
> 			return ...;
> 	} else if (kvm_advertise_xen()) {
> 		if (<handle xen msrs>)
> 			return ...;
> 	}
> 
> 	<fall through to main switch statement>
> 
> Obviously assumes KVM only advertises itself as one hypervisor, and so
> the ordering is arbitrary.

No, KVM can advertise as both KVM and Hyper-V.  CPUID 0x40000000 is used
for Hyper-V, while 0x40000100 is used for KVM.  The MSRs do not conflict.

Paolo