Re: [RFC PATCH v2 1/5] x86/cpu: Add virt tag in /proc/cpuinfo

[Sean Christopherson <seanjc@google.com>]

On Tue, Oct 01, 2024, Manali Shukla wrote:
> Add support for generating Virtualization feature names in capflags.c
> and use the resulting x86_virt_flags to print the virt flags in
> /proc/cpuinfo.
> 
> Currently, it is difficult to check if a feature is supported in _KVM_.
> Manually querying cpuid to know whether the feature is supported or not
> can be quite tedious at times.
> 
> Print the features supported in KVM hypervisor in a dedicated "virt"
> line instead of adding them to the common "flags".

First off, printing flags in a separate section doesn't magically connect them
to KVM support.  E.g. if you cut this series after patch 2, BUS_LOCK_THRESHOLD
will show up in "virt" despite KVM not supporting the feature.

Second, deviating from the X86_FEATURE_* syntax will make it _harder_ for KVM to
manage its configuration.

Third, this is completely orthogonal to supporting bus lock threshold in KVM,
i.e. belongs in a separate series.