linux-kernel - Re: [RFC PATCH 06/15] x86/microcode: Update the Intel processor flag scan check

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: <20241221091104.GBZ2aGKIXUMlpmrbQW@fat_crate.local>
Date: Sat, 21 Dec 2024 10:11:04 +0100
From: Borislav Petkov <bp@...en8.de>
To: Sohil Mehta <sohil.mehta@...el.com>
Cc: x86@...nel.org, Dave Hansen <dave.hansen@...ux.intel.com>,
	Tony Luck <tony.luck@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H . Peter Anvin" <hpa@...or.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>, Andy Lutomirski <luto@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Fenghua Yu <fenghua.yu@...el.com>, Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>, Zhang Rui <rui.zhang@...el.com>,
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-hwmon@...r.kernel.org
Subject: Re: [RFC PATCH 06/15] x86/microcode: Update the Intel processor flag
 scan check

On Fri, Dec 20, 2024 at 09:37:01PM +0000, Sohil Mehta wrote:
> The check whether to read IA32_PLATFORM_ID MSR is misleading. It doesn't
> seem to consider family while comparing the model number. This works
> because init_intel_microcode() bails out if the processor family is less
> than 6. It is better to update the current check to specifically include
> family 6.
> 
> Ideally, a VFM check would make it more readable. But, there isn't a
> macro to derive VFM from sig.
> 
> Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
> ---
>  arch/x86/kernel/cpu/microcode/intel.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
> index f3d534807d91..734819a12d5f 100644
> --- a/arch/x86/kernel/cpu/microcode/intel.c
> +++ b/arch/x86/kernel/cpu/microcode/intel.c
> @@ -74,7 +74,8 @@ void intel_collect_cpu_info(struct cpu_signature *sig)
>  	sig->pf = 0;
>  	sig->rev = intel_get_microcode_revision();
>  
> -	if (x86_model(sig->sig) >= 5 || x86_family(sig->sig) > 6) {
> +	/* TODO: Simplify this using a VFM check? */

No TODOs. Take your time and do it right from the get-go please.

-- 
Regards/Gruss,
    Boris.

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