linux-kernel - Re: [PATCH 1/2] x86/mce: Disable preemption for CPER decoding

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Message-ID: <5f40b5f0-3e19-5cf3-5bd3-eafa4d036119@amd.com>
Date:   Fri, 23 Jun 2023 12:14:00 -0400
From:   Yazen Ghannam <yazen.ghannam@....com>
To:     Borislav Petkov <bp@...en8.de>, "Luck, Tony" <tony.luck@...el.com>
Cc:     yazen.ghannam@....com,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH 1/2] x86/mce: Disable preemption for CPER decoding

On 6/23/2023 12:01 PM, Borislav Petkov wrote:
> On Fri, Jun 23, 2023 at 03:44:06PM +0000, Luck, Tony wrote:
>> There is (or was) support for mixed stepping in the microcode update
>> code. Not sure if Boris and Ashok came to any agreement on keeping it.
> 
> Yap, needs to stay on AMD as the loader has always supported it.
> 

I don't understand this. Maybe it's a wording thing. I see the following 
in a PPR document.

Section: Mixed Processor Revision Supports

AMD Family XXh Models XXh processors with different OPNs or different 
revisions cannot be mixed in a multiprocessor system. If the BIOS 
detects an unsupported configuration, the system will halt prior to X86 
core release and signal a port 80 error code.

Is stepping not included in this statement?

Or do you mean that we can support mixed microcode systems? Meaning the 
processors are identical but with different microcode versions.

Thanks,
Yazen