linux-kernel - Re: [PATCH 2/3] RAS/AMD/ATL: Require PRM support for future systems

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Message-ID: <20251016161037.GEaPEY_V0fbmPvspMa@fat_crate.local>
Date: Thu, 16 Oct 2025 18:10:37 +0200
From: Borislav Petkov <bp@...en8.de>
To: Yazen Ghannam <yazen.ghannam@....com>
Cc: "Rafael J. Wysocki" <rafael@...nel.org>, Len Brown <lenb@...nel.org>,
	Tony Luck <tony.luck@...el.com>, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
	Avadhut Naik <avadhut.naik@....com>,
	John Allen <john.allen@....com>,
	Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH 2/3] RAS/AMD/ATL: Require PRM support for future systems

On Mon, Oct 06, 2025 at 03:10:26PM +0000, Yazen Ghannam wrote:
> Currently, the AMD Address Translation Library will fail to load for
> new, unrecognized systems (based on Data Fabric revision). The intention
> is to prevent the code from executing on new systems and returning
> incorrect results.
> 
> Recent AMD systems may provide UEFI PRM handlers for address
> translation. This is code provided by the platform through BIOS tables.
> These are the preferred method for translation, and the Linux native
> code can be used as a fallback.
> 
> Future AMD systems are expected to provide PRM handlers by default. And
> Linux native code will not be used.
> 
> Adjust the ATL init code so that new, unrecognized systems will default
> to using PRM handlers only.
> 
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> ---
>  drivers/ras/amd/atl/internal.h | 10 +++++++++-
>  drivers/ras/amd/atl/prm.c      | 10 ++++++++++
>  drivers/ras/amd/atl/system.c   | 12 ++++++------
>  drivers/ras/amd/atl/umc.c      |  2 +-
>  4 files changed, 26 insertions(+), 8 deletions(-)

Try to simplify this this way:

Drop prm_check() and set prm_only *after* acpi_prm_handler_available() returns
true. Then use ->prm_only everywhere instead.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette