Re: [PATCH v11 055/113] KVM: x86/VMX: introduce vmx tlb_remote_flush and tlb_remote_flush_with_range

[Sean Christopherson]

On Tue, Jan 17, 2023, Huang, Kai wrote:
> On Thu, 2023-01-12 at 08:32 -0800, isaku.yamahata@xxxxxxxxx wrote:
> > --- a/arch/x86/kvm/mmu/mmu.c
> > +++ b/arch/x86/kvm/mmu/mmu.c
> > @@ -244,7 +244,7 @@ static void kvm_flush_remote_tlbs_with_range(struct kvm *kvm,
> >  {
> >  	int ret = -ENOTSUPP;
> >  
> > -	if (range && kvm_x86_ops.tlb_remote_flush_with_range)
> > +	if (range && kvm_available_flush_tlb_with_range())
> >  		ret = static_call(kvm_x86_tlb_remote_flush_with_range)(kvm, range);
> 
> Again, IMHO this code change doesn't make code any clearer.  With the new code,
> I need to go into the kvm_available_flush_tlb_with_range() to see what's going
> on, but with the old code I don't.

Agreed.  Though I think this patch as a whole can be replaced with a more
straightforward solution.

hv_remote_flush_tlb() is used when KVM is running as a Hyper-V guest, whereas
TDX requires running KVM on bare metal.  KVM should simply disallow TDX when a
hypervisor is detected, then there's no need for vmx_tlb_remote_flush_with_range().