linux-hardening - Re: [PATCH v3 08/10] perf/x86/rapl: Modify the generic variable names to *

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240705092416.GB11386@noisy.programming.kicks-ass.net>
Date: Fri, 5 Jul 2024 11:24:16 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: "Zhang, Rui" <rui.zhang@...el.com>
Cc: "Dhananjay.Ugwekar@....com" <Dhananjay.Ugwekar@....com>,
	"gautham.shenoy@....com" <gautham.shenoy@....com>,
	"alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>,
	"ananth.narayan@....com" <ananth.narayan@....com>,
	"dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
	"ravi.bangoria@....com" <ravi.bangoria@....com>,
	"Hunter, Adrian" <adrian.hunter@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"mingo@...hat.com" <mingo@...hat.com>,
	"oleksandr@...alenko.name" <oleksandr@...alenko.name>,
	"irogers@...gle.com" <irogers@...gle.com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"gustavoars@...nel.org" <gustavoars@...nel.org>,
	"kan.liang@...ux.intel.com" <kan.liang@...ux.intel.com>,
	"kees@...nel.org" <kees@...nel.org>,
	"sandipan.das@....com" <sandipan.das@....com>,
	"mark.rutland@....com" <mark.rutland@....com>,
	"linux-perf-users@...r.kernel.org" <linux-perf-users@...r.kernel.org>,
	"linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>,
	"bp@...en8.de" <bp@...en8.de>, "acme@...nel.org" <acme@...nel.org>,
	"kprateek.nayak@....com" <kprateek.nayak@....com>,
	"jolsa@...nel.org" <jolsa@...nel.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"namhyung@...nel.org" <namhyung@...nel.org>
Subject: Re: [PATCH v3 08/10] perf/x86/rapl: Modify the generic variable
 names to *_pkg*

On Fri, Jul 05, 2024 at 02:18:30AM +0000, Zhang, Rui wrote:

> > > > I have a doubt about this, won't the future Intel multi-die
> > > > systems 
> > > > have die-scope for the RAPL PMU like Casecadelake-AP?
> > > 
> > > For future multi-die systems that I know, the RAPL is still package
> > > scope 
> > 
> > I think in that case we can go with rule 2, it would be future proof
> > for Intel systems. If you agree, I can make the change in next
> > version.
> > 
> > Something like below?,
> > 
> > -#define rapl_pmu_is_pkg_scope()                         \
> > -        (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || 
> > \                                                                    
> >                                                                      
> >                          
> > -        boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)
> > 
> > +#define rapl_pmu_is_die_scope()                        \
> > +       (boot_cpu_data.x86_model_id == CASCADELAKE)
> > 
> sounds good to me. Just a reminder that using boot_cpu_data.vfm is a
> better choice here.
> 
> And it would be great to get Peter' view on this.

Peter is confused :-) So you're saying that:

 - old Intel is pkg wide (it has no DIE enumeration)
 - Cascadelake (part of the skylake refresh) is per-DIE
 - modern Intel is pkg wide (they have no DIE enumeration)
 - future Intel will be pkg wide

And this works because for everything that does not enumerate a specific
DIE topology, it ends up begin the same as the PKG topology.

But what about future products that have DIE but are not CASCADE (what
about COOPERLAKE) ?

If this really is a one off for CASCADE, then yes, I think we should be
doing what Dhananjay suggests, and then the PKG naming is fine.