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

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Date:   Tue, 8 Nov 2022 15:06:20 -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

Hi Boris,

On Mon, Nov 07, 2022 at 07:47:37PM +0100, Borislav Petkov wrote:
> On Mon, Nov 07, 2022 at 04:12:59PM +0000, Ashok Raj wrote:
> > Only missing is the ucode date, not a big deal missing it.
> 
> Yes, it isn't. One can find it out another way:
> 
> $ iucode-tool -l /lib/firmware/intel-ucode/06-9c-00
> microcode bundle 1: /lib/firmware/intel-ucode/06-9c-00
> selected microcodes:
>   001/001: sig 0x000906c0, pf_mask 0x01, 2022-02-19, rev 0x24000023, size 20480
>   					 ^^^^^^^^^^

That's correct, my thought as well. Did you get a chance to review rest of
the patches? 

Thought I'll wait for more comments before I send the next rev.

Patch2 is a simple fix that you suggested.

Patch3 is a bug fix. I suspect some earlier upstream reports of ucode 
failure after update (early loading) might be related. The symptom is 
similar, but those are too old to followup. I got into a similare situation
when i tried to update an incompatible uCode from initrd and system hung.

I'm not positive, but seems highly likely. The following are early loading
failures, not late loading.

https://bugs.launchpad.net/ubuntu/+source/intel-microcode/+bug/1911959

https://forums.linuxmint.com/viewtopic.php?p=1827032#1827032

https://askubuntu.com/questions/1291486/boot-crash-after-latest-update-of-intel-microcode-nov-11-2020

Patch 4 is also a bugfix, today when we reload the same ucode even though
nothing changes it seems to think some feature is new. When i added some
more debug it turned out SGX was probably turned off by OS, but enumerated
by microcode. So it always reports 

Cheers,
Ashok