linux-kernel - Re: 4.15.17 regression: bisected: timeout during microcode update

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Date:   Wed, 18 Apr 2018 06:53:30 -0700
From:   "Raj, Ashok" <ashok.raj@...el.com>
To:     Borislav Petkov <bp@...e.de>
Cc:     Vitezslav Samel <vitezslav@...el.cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, Ashok Raj <ashok.raj@...el.com>
Subject: Re: 4.15.17 regression: bisected: timeout during microcode update

On Wed, Apr 18, 2018 at 02:22:12PM +0200, Borislav Petkov wrote:
> On Wed, Apr 18, 2018 at 02:08:40PM +0200, Vitezslav Samel wrote:
> > I switched to firmware-in-kernel early loading and that works OK.

firmware-in-kernel means you compile your microcode image in linux?

Can you tell me which distro you are using? The ones we used 
doesn't do late-loading (i.e echo 1 > /sys/devices/system/cpu/microcode/reload)

I suspect that might be the problem. 

- Can you remove your builtin microcode, 
- rename the /lib/firmware/intel-ucode so we don't find it during late
loading. 
- let the system boot completely
- then rename the intel-ucode back for this test.
- write 1 to reload and see if that update succeeds or fails?


> 
> Ok, and keep using that from now on.
> 
> People should all move away from that late loading dance. I'm saying
> that in case someone else reads this on lkml.
> 
> > But still, the reported issue is regression in 4.15.17 and 4.16+.
> 
> Oh, I know it is a regression.
> 
> @Ashok: anything particular about his microcode revision not being able
> to stomach late loading?

nothing about the microcode itself comes to mind. I'm wondering if this 
similar to the Arch linux that used late-load during booting might be an issue.