Re: [PATCH 3/6] KVM: VMX: Detect Tertiary VM-Execution control when setup VMCS config

[Zeng Guang]

On 7/29/2021 8:03 AM, Sean Christopherson wrote:
> On Fri, Jul 16, 2021, Zeng Guang wrote:
> > @@ -4204,6 +4234,13 @@ vmx_adjust_secondary_exec_control(struct vcpu_vmx *vmx, u32 *exec_control,
> >   #define vmx_adjust_sec_exec_exiting(vmx, exec_control, lname, uname) \
> >   	vmx_adjust_sec_exec_control(vmx, exec_control, lname, uname, uname##_EXITING, true)
> >   
> > +static void vmx_compute_tertiary_exec_control(struct vcpu_vmx *vmx)
> > +{
> > +	u32 exec_control = vmcs_config.cpu_based_3rd_exec_ctrl;
> This is incorrectly truncating the value.
>
> > +
> > +	vmx->tertiary_exec_control = exec_control;
> > +}
> > +
> >   static void vmx_compute_secondary_exec_control(struct vcpu_vmx *vmx)
> >   {
> >   	struct kvm_vcpu *vcpu = &vmx->vcpu;
> > @@ -4319,6 +4356,11 @@ static void init_vmcs(struct vcpu_vmx *vmx)
> >   		secondary_exec_controls_set(vmx, vmx->secondary_exec_control);
> >   	}
> >   
> > +	if (cpu_has_tertiary_exec_ctrls()) {
> > +		vmx_compute_tertiary_exec_control(vmx);
> > +		tertiary_exec_controls_set(vmx, vmx->tertiary_exec_control);
> IMO, the existing vmx->secondary_exec_control is an abomination that should not
> exist.  Looking at the code, it's actually not hard to get rid, there's just one
> annoying use in prepare_vmcs02_early() that requires a bit of extra work to get
> rid of.
>
> Anyways, for tertiary controls, I'd prefer to avoid the same mess and instead
> follow vmx_exec_control(), both in functionality and in name:
>
>    static u64 vmx_tertiary_exec_control(struct vcpu_vmx *vmx)
>    {
> 	return vmcs_config.cpu_based_3rd_exec_ctrl;
>    }
>
> and:
>
> 	if (cpu_has_tertiary_exec_ctrls())
> 		tertiary_exec_controls_set(vmx, vmx_tertiary_exec_control(vmx));
>
> and then the next patch becomes:
>
>    static u64 vmx_tertiary_exec_control(struct vcpu_vmx *vmx)
>    {
> 	u64 exec_control = vmcs_config.cpu_based_3rd_exec_ctrl;
>
> 	if (!kvm_vcpu_apicv_active(vcpu))
> 		exec_control &= ~TERTIARY_EXEC_IPI_VIRT;
>
> 	return exec_control;
>    }
>
>
> And I'll work on a patch to purge vmx->secondary_exec_control.
Ok, it looks much concise. I will change as you suggest. Thanks.
> > +	}
> > +
> >   	if (kvm_vcpu_apicv_active(&vmx->vcpu)) {
> >   		vmcs_write64(EOI_EXIT_BITMAP0, 0);
> >   		vmcs_write64(EOI_EXIT_BITMAP1, 0);
> > diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
> > index 945c6639ce24..c356ceebe84c 100644
> > --- a/arch/x86/kvm/vmx/vmx.h
> > +++ b/arch/x86/kvm/vmx/vmx.h
> > @@ -266,6 +266,7 @@ struct vcpu_vmx {
> >   	u32		      msr_ia32_umwait_control;
> >   
> >   	u32 secondary_exec_control;
> > +	u64 tertiary_exec_control;
> >   
> >   	/*
> >   	 * loaded_vmcs points to the VMCS currently used in this vcpu. For a
> > --
> > 2.25.1