linux-kernel - Re: [PATCH] x86/amd_nb: Check for invalid SMN reads

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Message-ID: <20230510113553.GAZFuBmZbhAFkbqm1a@fat_crate.local>
Date:   Wed, 10 May 2023 13:35:53 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Yazen Ghannam <yazen.ghannam@....com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/amd_nb: Check for invalid SMN reads

On Wed, Apr 05, 2023 at 03:10:09PM -0400, Yazen Ghannam wrote:
> What do you think?

Yes, please put that as a comment over __amd_smn_rw() as to why callers
should check the retval *and* make both the read and the write
__must_check and get rid of

        if (err)
                pr_warn("Error %s SMN address 0x%x.\n",
                        (write ? "writing to" : "reading from"), address);

which won't be seen in all cases. The __must_check will force the
callers to do the proper checking which is the only sane thing to do
with such a variety of bit behaviors.

Thx.

-- 
Regards/Gruss,
    Boris.

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