linux-kernel - Re: [PATCH v4 11/19] x86/cpu: Print VMX flags in /proc/cpuinfo using VMX_FEATURES

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Date:   Thu, 12 Dec 2019 13:26:46 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Sean Christopherson <sean.j.christopherson@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Tony Luck <tony.luck@...el.com>,
        Tony W Wang-oc <TonyWWang-oc@...oxin.com>,
        Len Brown <lenb@...nel.org>, Shuah Khan <shuah@...nel.org>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-edac@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kselftest@...r.kernel.org,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Subject: Re: [PATCH v4 11/19] x86/cpu: Print VMX flags in /proc/cpuinfo using
 VMX_FEATURES_*

On Wed, Nov 27, 2019 at 05:40:08PM -0800, Sean Christopherson wrote:
> Add support for generating VMX feature names in capflags.c and use the
> resulting x86_vmx_flags to print the VMX flags in /proc/cpuinfo.  Don't
> print VMX flags if no bits are set in word 0, which holds Pin Controls.
> Pin Control's INTR and NMI exiting are fundamental pillars of VMX, if
> they are not supported then the CPU is broken, it does not actually
> support VMX, or the kernel wasn't built with support for the target CPU.
> 
> Print the features in a dedicated "vmx flags" line to avoid polluting
> the common "flags" and to avoid having to prefix all flags with "vmx_",
> which results in horrendously long names.
> 
> Keep synthetic VMX flags in cpufeatures to preserve /proc/cpuinfo's ABI
> for those flags.  This means that "flags" and "vmx flags" will have
> duplicate entries for tpr_shadow (virtual_tpr), vnmi (virtual_nmis),
> ept, flexpriority, vpid and ept_ad, but caps the pollution of "flags" at
> those six VMX features.  The vendor specific code that populates the
> synthetic flags will be consolidated in a future patch to futher
								^

further

> +#ifdef CONFIG_X86_VMX_FEATURE_NAMES
> +	if (cpu_has(c, X86_FEATURE_VMX) && c->vmx_capability[0]) {
> +		seq_puts(m, "\nvmx flags\t:");
> +		for (i = 0; i < 32*NVMXINTS; i++) {
> +			if (test_bit(i, (unsigned long *)c->vmx_capability) &&
> +			    x86_vmx_flags[i] != NULL)
> +				seq_printf(m, " %s", x86_vmx_flags[i]);
> +		}
> +	}
> +#endif

Oh well, some could be shorter:

vmx flags       : virtual_nmis preemption_timer invvpid ept_x_only ept_ad ept_1gb flexpriority tsc_offsetting virtual_tpr mtf virt_apic_accesses ept vpid unrestricted_guest ple shadow_vmcs pml mode_based_ept_exec

virtual_nmis		-> vnmis
preemption_timer	-> preempt_tmr
flexpriority		-> flexprio
tsc_offsetting		-> tsc_ofs
virtual_tpr		-> vtpr
virt_apic_accesses	-> vapic
unrestricted_guest	-> unres_guest

and so on. Those are just my examples - I betcha the SDM is more
creative here with abbreviations. But you guys are going to grep for
them. If it were me, I'd save on typing. :-)

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette