linux-kernel - Re: [v2 01/13] x86/microcode/intel: Prevent printing updated microcode rev multiple times

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Message-ID: <Y2iGw8U8JGMJ+aKq@a4bf019067fa.jf.intel.com>
Date:   Sun, 6 Nov 2022 20:17:07 -0800
From:   Ashok Raj <ashok.raj@...el.com>
To:     Borislav Petkov <bp@...en8.de>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        LKML Mailing List <linux-kernel@...r.kernel.org>,
        X86-kernel <x86@...nel.org>, Tony Luck <tony.luck@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Arjan van de Ven <arjan.van.de.ven@...el.com>,
        Andy Lutomirski <luto@...nel.org>,
        "Jacon Jun Pan" <jacob.jun.pan@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        "Kai Huang" <kai.huang@...el.com>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [v2 01/13] x86/microcode/intel: Prevent printing updated
 microcode rev multiple times

On Sun, Nov 06, 2022 at 02:35:58PM +0100, Borislav Petkov wrote:
> On Thu, Nov 03, 2022 at 05:58:49PM +0000, Ashok Raj wrote:
> > @@ -696,8 +697,7 @@ static int collect_cpu_info(int cpu_num, struct cpu_signature *csig)
> >  
> >  	csig->rev = c->microcode;
> >  
> > -	/* No extra locking on prev, races are harmless. */
> > -	if (csig->sig != prev.sig || csig->pf != prev.pf || csig->rev != prev.rev) {
> > +	if (bsp && csig->rev != prev.rev) {
> >  		pr_info("sig=0x%x, pf=0x%x, revision=0x%x\n",
> >  			csig->sig, csig->pf, csig->rev);
> 
> And now that we've established that we don't do mixed steppings anymore
> and the microcode revision is the same system-wide, you should simply
> drop this pr_info(), in your next patch you're adding
> 
> +static u32 early_old_rev;
> 
> That thing should simply be
> 
> /* Currently applied microcode revision */
> static u32 microcode_rev;
> 
> and you simply update that one each time you update microcode and print
> it as the previous and the new one and then write the new one into this
> var and that's it. Simple.
> 

I thought about it... Since microcode/core.c already provides this
information. Only missing part is the microcode date which the common
function doesn't seem to get this. Thought it might be useful. But I can
certainly drop it, if you think this isn't much value.