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

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Thu, Dec 12, 2019 at 04:57:10PM +0100, Paolo Bonzini wrote:
> 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.

Key word being "usually".  My intent in printing out partially redundant
flags was to help users debug/understand why the combined feature isn't
supported.  E.g. userspace can already easily (relatively speaking) query
flexpriority support via /sys/module/kvm_intel/parameters/flexpriority.
But if that comes back "N", the user has no way to determine exactly why
flexpriority is disabled.



[Index of Archives]     [Linux Wireless]     [Linux Kernel]     [ATH6KL]     [Linux Bluetooth]     [Linux Netdev]     [Kernel Newbies]     [Share Photos]     [IDE]     [Security]     [Git]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Linux ATA RAID]     [Samba]     [Device Mapper]

  Powered by Linux