linux-kernel - Re: [PATCH 11/16] x86/cpu: Print VMX features as separate line item in /proc/cpuinfo

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Date:   Mon, 7 Oct 2019 12:56:38 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Peter Zijlstra <peterz@...radead.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Tony Luck <tony.luck@...el.com>,
        Tony W Wang-oc <TonyWWang-oc@...oxin.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-edac@...r.kernel.org,
        Borislav Petkov <bp@...e.de>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Subject: Re: [PATCH 11/16] x86/cpu: Print VMX features as separate line item
 in /proc/cpuinfo

On Mon, Oct 07, 2019 at 07:12:37PM +0200, Paolo Bonzini wrote:
> On 04/10/19 23:56, Sean Christopherson wrote:
> > diff --git a/arch/x86/kernel/cpu/proc.c b/arch/x86/kernel/cpu/proc.c
> > index cb2e49810d68..4eec8889b0ff 100644
> > --- a/arch/x86/kernel/cpu/proc.c
> > +++ b/arch/x86/kernel/cpu/proc.c
> > @@ -7,6 +7,10 @@
> >  
> >  #include "cpu.h"
> >  
> > +#ifdef CONFIG_X86_VMX_FEATURE_NAMES
> > +extern const char * const x86_vmx_flags[NVMXINTS*32];
> > +#endif
> > +
> >  /*
> >   *	Get CPU information for use by the procfs.
> >   */
> > @@ -102,6 +106,17 @@ static int show_cpuinfo(struct seq_file *m, void *v)
> >  		if (cpu_has(c, i) && x86_cap_flags[i] != NULL)
> >  			seq_printf(m, " %s", x86_cap_flags[i]);
> 
> I'm afraid this is going to break some scripts in the wild.  I would
> simply remove the seq_puts below.

Can you elaborate?  I'm having trouble connecting the dots...

> Paolo
> 
> > +#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
> > +
> >  	seq_puts(m, "\nbugs\t\t:");
> >  	for (i = 0; i < 32*NBUGINTS; i++) {
> >  		unsigned int bug_bit = 32*NCAPINTS + i;