Re: [PATCH v2 28/28] KVM: nVMX: Use cached host MSR_IA32_VMX_MISC value for setting up nested MSR

From: Vitaly Kuznetsov
Date: Thu Jun 30 2022 - 03:36:51 EST


Jim Mattson <jmattson@xxxxxxxxxx> writes:

> On Wed, Jun 29, 2022 at 8:07 AM Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> wrote:
>>
>> vmcs_config has cased host MSR_IA32_VMX_MISC value, use it for setting
>> up nested MSR_IA32_VMX_MISC in nested_vmx_setup_ctls_msrs() and avoid the
>> redundant rdmsr().
>>
>> No (real) functional change intended.
>
> Just imaginary functional change? :-)
>

Well, yea) The assumption here is that MSR_IA32_VMX_MISC's value doesn't
change underneath KVM, caching doesn't change anything then. It is, of
course, possible that when KVM runs as a nested hypervisor on top of
something else, it will observe different values. I truly hope this is
purely imaginary :-)

>>
>> Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
> Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
>

Thanks!

--
Vitaly