Re: [PATCH RESEND v4 5/9] KVM: VMX: Add init/set/get functions for SPP

Yang Weijiang
2019-08-20T13:08:01Z

On Mon, Aug 19, 2019 at 05:13:47PM +0200, Paolo Bonzini wrote:
> On 14/08/19 09:03, Yang Weijiang wrote:
> > static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
> > .cpu_has_kvm_support = cpu_has_kvm_support,
> > .disabled_by_bios = vmx_disabled_by_bios,
> > @@ -7740,6 +7783,11 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
> > .get_vmcs12_pages = NULL,
> > .nested_enable_evmcs = NULL,
> > .need_emulation_on_page_fault = vmx_need_emulation_on_page_fault,
> > +
> > + .get_spp_status = vmx_get_spp_status,
> > + .get_subpages = vmx_get_subpages,
> > + .set_subpages = vmx_set_subpages,
> > + .init_spp = vmx_init_spp,
> > };
>
> There's no need for the get_subpages kvm_x86_ops. You do need init_spp
> of course, but you do not need get_spp_status either; instead you can
> check if init_spp is NULL (if NULL, SPP is not supported).
So first set .init_spp = NULL, then if all SPP preconditions meet, set
.init_spp = vmx_init_spp?

> In addition, kvm_mmu_set_subpages should not set up the SPP pages. This
> should be handled entirely by handle_spp when the processor reports an
> SPPT miss, so you do not need that callback either. You may need a
> flush_subpages callback, called by kvm_mmu_set_subpages to clear the SPP
> page tables for a given GPA range. The next access then will cause an
> SPPT miss.
Good suggestion, thanks! Will do change.

> Finally, please move all SPP-related code to arch/x86/kvm/vmx/{spp.c,spp.h}.
>
Sure.

> Thanks,
>
> Paolo
>