RE: [PATCH v3 22/22] kvm: x86: Disable interception for IA32_XFD on demand

[Tian, Kevin]

> From: Sean Christopherson <seanjc@xxxxxxxxxx>
> Sent: Wednesday, December 29, 2021 9:05 AM
> > +	if (vcpu->arch.xfd_out_of_sync)
> 
> Rather than adding a flag that tracks whether or not the MSR can be written
> by
> the guest, can't this be:
> 
> 	if (!vmx_test_msr_bitmap_write(vcpu->loaded_vmcs->msr_bitmap))
> 		fpu_sync_guest_vmexit_xfd_state();
> 

and forgot to mention a change different from above. It's in x86
common exit path but above is vmx specific check. I'm not sure
whether it's worthy of introducing another kvm_x86_ops callback
just for this minor usage.

Introducing an extra flag (e.g. vcpu->arch.xfd_disable_interception)
sounds simpler here.

Thanks
Kevin