linux-kernel - Re: [PATCH] x86/MCE: Prevent CPU offline for SMCA CPUs with non-core banks

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Message-ID: <87jzg4g8dm.ffs@tglx>
Date: Sun, 25 Aug 2024 13:16:37 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Yazen Ghannam <yazen.ghannam@....com>, linux-edac@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, tony.luck@...el.com, x86@...nel.org,
 avadhut.naik@....com, john.allen@....com, boris.ostrovsky@...cle.com,
 Yazen Ghannam <yazen.ghannam@....com>
Subject: Re: [PATCH] x86/MCE: Prevent CPU offline for SMCA CPUs with
 non-core banks

On Wed, Aug 21 2024 at 09:00, Yazen Ghannam wrote:
> Logical CPUs in AMD Scalable MCA (SMCA) systems can manage non-core
> banks. Each of these banks represents unique and separate hardware
> located within the system. Each bank is managed by a single logical CPU;
> they are not shared. Furthermore, the "CPU to MCA bank" assignment
> cannot be modified at run time.
>
> The MCE subsystem supports run time CPU hotplug. Many vendors have
> non-core MCA banks, so MCA settings are not cleared when a CPU is
> offlined for these vendors.
>
> Even though the non-core MCA banks remain enabled, MCA errors will not
> be handled (reported, cleared, etc.) on SMCA systems when the managing
> CPU is offline.
>
> Check if a CPU manages non-core MCA banks and, if so, prevent it from
> being taken offline.

Which in turn breaks hibernation and kexec...

Thanks,

        tglx