Re: [PATCH v3 25/25] KVM: nVMX: Use cached host MSR_IA32_VMX_MISC value for setting up nested MSR

Maxim Levitsky
2022-07-12T12:12:07Z

On Fri, 2022-07-08 at 16:42 +0200, Vitaly Kuznetsov wrote:
> vmcs_config has cased host MSR_IA32_VMX_MISC value, use it for setting
^^ typo
> up nested MSR_IA32_VMX_MISC in nested_vmx_setup_ctls_msrs() and avoid the
> redundant rdmsr().
>
> No (real) functional change intended.
>
> Reviewed-by: Jim Mattson <jmattson@google.com>
> Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
> ---
>  arch/x86/kvm/vmx/nested.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> index 3d386c663fac..8026dab71086 100644
> --- a/arch/x86/kvm/vmx/nested.c
> +++ b/arch/x86/kvm/vmx/nested.c
> @@ -6754,10 +6754,7 @@ void nested_vmx_setup_ctls_msrs(struct vmcs_config *vmcs_conf, u32 ept_caps)
>                 msrs->secondary_ctls_high |= SECONDARY_EXEC_ENCLS_EXITING;
>
>         /* miscellaneous data */
> -       rdmsr(MSR_IA32_VMX_MISC,
> -               msrs->misc_low,
> -               msrs->misc_high);
> -       msrs->misc_low &= VMX_MISC_SAVE_EFER_LMA;
> +       msrs->misc_low = (u32)vmcs_conf->misc & VMX_MISC_SAVE_EFER_LMA;
>         msrs->misc_low |=
>                 MSR_IA32_VMX_MISC_VMWRITE_SHADOW_RO_FIELDS |
>                 VMX_MISC_EMULATED_PREEMPTION_TIMER_RATE |

Besides the typo,
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>

Best regards,
Maxim Levitsky