linux-kernel - Re: Fix built-in early-load Intel microcode alignment

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Message-Id: <5C216684-6FDF-41B5-9F51-89DC295F6DDC@amacapital.net>
Date:   Wed, 15 Jan 2020 11:00:29 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Jari Ruusu <jari.ruusu@...il.com>
Cc:     Luis Chamberlain <mcgrof@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Fenghua Yu <fenghua.yu@...el.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        johannes.berg@...el.com, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: Fix built-in early-load Intel microcode alignment



> On Jan 15, 2020, at 10:46 AM, Jari Ruusu <jari.ruusu@...il.com> wrote:
> 
> On 1/15/20, Luis Chamberlain <mcgrof@...nel.org> wrote:
>>> On Mon, Jan 13, 2020 at 09:58:25PM +0200, Jari Ruusu wrote:
>>> Before that 16-byte alignment patch was applied, my only one
>>> microcode built-in BLOB was "accidentally" 16-byte aligned.
>> 
>> How did it accidentially get 16-byte aligned?
> 
> Old code aligned it to 8-bytes.
> There is 50/50-chance of it also being 16-byte aligned.
> So it ended up being both 8-byte and 16-byte aligned.
> 
>> Also, how do you *know* something is broken right now?
> 
> I haven't spotted brokenness in Linux microcode loader other
> than that small alignment issue.
> 
> However, I can confirm that there are 2 microcode updates newer
> than what my laptop computer's latest BIOS includes. Both newer
> ones (20191115 and 20191112) are unstable on my laptop computer
> i5-7200U (fam 6 model 142 step 9 pf 0x80). Hard lockups with both
> of them. Back to BIOS microcode for now.
> 

Hard lockup when loaded or hard lockup after loading?

> -- 
> Jari Ruusu  4096R/8132F189 12D6 4C3A DCDA 0AA4 27BD  ACDF F073 3C80 8132 F189