linux-kernel - Re: [PATCH v3 2/5] x86/microcode/intel: Allow a late-load only if a min rev is specified

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Date:   Tue, 23 Aug 2022 00:08:27 +0000
From:   Ashok Raj <ashok.raj@...el.com>
To:     Borislav Petkov <bp@...en8.de>
CC:     Thomas Gleixner <tglx@...utronix.de>,
        Tony Luck <tony.luck@...el.com>,
        Dave Hansen <dave.hansen@...el.com>,
        LKML Mailing List <linux-kernel@...r.kernel.org>,
        X86-kernel <x86@...nel.org>,
        Andy Lutomirski <luto@...capital.net>,
        Tom Lendacky <thomas.lendacky@....com>,
        Jacon Jun Pan <jacob.jun.pan@...el.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [PATCH v3 2/5] x86/microcode/intel: Allow a late-load only if a
 min rev is specified

Hi Boris

> >  struct microcode_intel {
> > diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
> > index c4b11e2fbe33..1eb202ec2302 100644
> > --- a/arch/x86/kernel/cpu/microcode/intel.c
> > +++ b/arch/x86/kernel/cpu/microcode/intel.c
> > @@ -178,6 +178,7 @@ static int microcode_sanity_check(void *mc, int print_err)
> 
> You can't do this in this function:
> 
> load_ucode_intel_bsp -> __load_ucode_intel -> scan_microcode -> microcode_sanity_check
> 
> which is the early path.

Correct, but print_err parameter is 0 when called from scan_microcode() and 1
when called from generic_load_microcode().

We do min_rev enforcement only when print_err is set.

Should I change the parameter to "late_loading" instead so the
meaning is clear. Let me know if I that's preferred.

Cheers,
Ashok