linux-kernel - Re: [PATCH 1/3] x86/amd_nb: Add support for HSMP mailbox access

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Message-ID: <YTEQzIVfY/A1uy32@zn.tnic>
Date:   Thu, 2 Sep 2021 19:58:36 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Naveen Krishna Chatradhi <nchatrad@....com>
Cc:     linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
        x86@...nel.org, linux@...ck-us.net, yazen.ghannam@....com,
        mingo@...hat.com, nathan.fontenot@....com, lewis.carroll@....com,
        Ingo Molnar <mingo@...nel.org>,
        Jean Delvare <jdelvare@...e.com>
Subject: Re: [PATCH 1/3] x86/amd_nb: Add support for HSMP mailbox access

On Thu, Sep 02, 2021 at 11:11:53PM +0530, Naveen Krishna Chatradhi wrote:
> On Fam19h server CPUs from AMD an HSMP (Host System Management Port)
> mailbox interface is added to monitor and manage the CPU parameters.

Mailbox? Hmm, that rings a bell. There's drivers/mailbox/ with a bunch
of drivers in there. Those are

"Mailbox is a framework to control hardware communication between
on-chip processors through queued messages and interrupt driven
signals."

I wonder if that HSMP thing can be wrapped like a mailbox driver...

If not, I still don't like it being slapped in amd_nb.c where it would
be built in on *all* AMD hardware which is kinda too much.

You could make it a separate driver module called amd_hsmp.ko which
loads only on the appropriate hw and uses amd_nb.c for detection only
like the other drivers, for example.

-- 
Regards/Gruss,
    Boris.

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