Re: [PATCH v4 11/19] x86/cpu: Print VMX flags in /proc/cpuinfo using VMX_FEATURES_*

Paolo Bonzini
2019-12-12T15:57:25Z

On 12/12/19 16:52, Liran Alon wrote:
>>> virt_apic_accesses -> vapic
>> apicv
> Frankly, I dislike APICv terminology. I prefer to enumerate the
> various VMX features which are collectively called APICv by KVM.
> APICv currently represents in KVM terminology the combination of
> APIC-register virtualization, virtual-interrupt-delivery and
> posted-interrupts (See cpu_has_vmx_apicv()).
>
> In fact, the coupling of “enable_apicv” module parameter have made me
> multiple times to need to disable entire APICv features when there
> for example was only a bug in posted-interrupts.
>
> Even you got confused as virtualize-apic-access is not part of KVM’s
> APICv terminology but rather it’s enablement depend on
> flexpriority_enabled (See cpu_need_virtualize_apic_accesses()). i.e.
> It can be used for faster intercept handling of accesses to guest
> xAPIC MMIO page.

Right, I got confused with APIC-register virtualization. Virtualize
APIC accesses is another one I wouldn't bother putting in /proc/cpuinfo,
since it's usually present together with flexpriority.

Paolo