Re: [PATCH v4 11/25] KVM: VMX: Get rid of eVMCS specific VMX controls sanitization

[Maxim Levitsky]

On Thu, 2022-07-14 at 11:13 +0200, Vitaly Kuznetsov wrote:
> With the updated eVMCSv1 definition, there's no known 'problematic'
> controls which are exposed in VMX control MSRs but are not present in
> eVMCSv1. Get rid of VMX control MSRs filtering for KVM on Hyper-V.

I think it still might be worth it, mentioning at least in the commit message,
that as you said, the all known HyperV versions, either don't expose the 
new fields by not setting bits in the VMX feature controls, 
or support the new eVMCS revision.

But anyway:

Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>

Best regards,
	Maxim Levitsky

> 
> Note: VMX control MSRs filtering for Hyper-V on KVM
> (nested_evmcs_filter_control_msr()) stays as even the updated eVMCSv1
> definition doesn't have all the features implemented by KVM and some
> fields are still missing. Moreover, nested_evmcs_filter_control_msr()
> has to support the original eVMCSv1 version when VMM wishes so.
> 
> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> ---
>  arch/x86/kvm/vmx/evmcs.c | 13 -------------
>  arch/x86/kvm/vmx/evmcs.h |  1 -
>  arch/x86/kvm/vmx/vmx.c   |  5 -----
>  3 files changed, 19 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/evmcs.c b/arch/x86/kvm/vmx/evmcs.c
> index 52a53debd806..b5cfbf7d487b 100644
> --- a/arch/x86/kvm/vmx/evmcs.c
> +++ b/arch/x86/kvm/vmx/evmcs.c
> @@ -320,19 +320,6 @@ const struct evmcs_field vmcs_field_to_evmcs_1[] = {
>  };
>  const unsigned int nr_evmcs_1_fields = ARRAY_SIZE(vmcs_field_to_evmcs_1);
>  
> -#if IS_ENABLED(CONFIG_HYPERV)
> -__init void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf)
> -{
> -       vmcs_conf->cpu_based_exec_ctrl &= ~EVMCS1_UNSUPPORTED_EXEC_CTRL;
> -       vmcs_conf->pin_based_exec_ctrl &= ~EVMCS1_UNSUPPORTED_PINCTRL;
> -       vmcs_conf->cpu_based_2nd_exec_ctrl &= ~EVMCS1_UNSUPPORTED_2NDEXEC;
> -       vmcs_conf->cpu_based_3rd_exec_ctrl = 0;
> -
> -       vmcs_conf->vmexit_ctrl &= ~EVMCS1_UNSUPPORTED_VMEXIT_CTRL;
> -       vmcs_conf->vmentry_ctrl &= ~EVMCS1_UNSUPPORTED_VMENTRY_CTRL;
> -}
> -#endif
> -
>  bool nested_enlightened_vmentry(struct kvm_vcpu *vcpu, u64 *evmcs_gpa)
>  {
>         struct hv_vp_assist_page assist_page;
> diff --git a/arch/x86/kvm/vmx/evmcs.h b/arch/x86/kvm/vmx/evmcs.h
> index 4b809c79ae63..0feac101cce4 100644
> --- a/arch/x86/kvm/vmx/evmcs.h
> +++ b/arch/x86/kvm/vmx/evmcs.h
> @@ -203,7 +203,6 @@ static inline void evmcs_load(u64 phys_addr)
>         vp_ap->enlighten_vmentry = 1;
>  }
>  
> -__init void evmcs_sanitize_exec_ctrls(struct vmcs_config *vmcs_conf);
>  #else /* !IS_ENABLED(CONFIG_HYPERV) */
>  static __always_inline void evmcs_write64(unsigned long field, u64 value) {}
>  static inline void evmcs_write32(unsigned long field, u32 value) {}
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index b4915d841357..dd905ad72637 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -2689,11 +2689,6 @@ static __init int setup_vmcs_config(struct vmcs_config *vmcs_conf,
>         vmcs_conf->vmexit_ctrl         = _vmexit_control;
>         vmcs_conf->vmentry_ctrl        = _vmentry_control;
>  
> -#if IS_ENABLED(CONFIG_HYPERV)
> -       if (enlightened_vmcs)
> -               evmcs_sanitize_exec_ctrls(vmcs_conf);
> -#endif
> -
>         return 0;
>  }
>