linux-kernel - Re: [PATCH] x86/microcode/intel: Quieten down microcode updates on large systems

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: <20160610095439.GA6706@pd.tnic>
Date:	Fri, 10 Jun 2016 11:54:39 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	x86@...nel.org, hmh@....eng.br, elliott@....com,
	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH] x86/microcode/intel: Quieten down microcode updates on
 large systems

On Thu, Jun 09, 2016 at 06:41:41AM -0700, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> On large systems the microcode driver is very noisy, because it prints
> a line for each CPU. The lines are redundant because because usually
> all CPUs are updated to the same microcode revision.
> 
> All other subsystems have been patched previously to not print
> a line for each CPU. Only the microcode driver is left.
> 
> Only print an microcode revision update when something changed. This results
> in typically only a single line being printed.
> 
> v2: Change message to "One or more CPUs"
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>  arch/x86/kernel/cpu/microcode/intel.c | 25 ++++++++++++++++++-------
>  1 file changed, 18 insertions(+), 7 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
> index cbb3cf0..54f5f6c 100644
> --- a/arch/x86/kernel/cpu/microcode/intel.c
> +++ b/arch/x86/kernel/cpu/microcode/intel.c
> @@ -794,6 +794,7 @@ void reload_ucode_intel(void)
>  
>  static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
>  {
> +	static struct cpu_signature prev;
>  	struct cpuinfo_x86 *c = &cpu_data(cpu_num);
>  	unsigned int val[2];
>  
> @@ -808,8 +809,14 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
>  	}
>  
>  	csig->rev = c->microcode;
> -	pr_info("CPU%d sig=0x%x, pf=0x%x, revision=0x%x\n",
> -		cpu_num, csig->sig, csig->pf, csig->rev);
> +
> +	/* No extra locking on prev, races are harmless. */
> +	if (csig->sig != prev.sig || csig->pf != prev.pf ||
> +	    csig->rev != prev.rev) {
> +		pr_info("One or more CPUs sig=0x%x, pf=0x%x, revision=0x%x\n",

This "One or more CPUs" is just silly. I've removed it while applying.
This way, there's no mentioning of CPUs and people can check
/proc/cpuinfo for that.

Thanks.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.