linux-kernel - Re: [PATCH] x86/microcode: allow non-root reading of microcode version and processor flags

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Message-ID: <20180827040620.GB14577@nazgul.tnic>
Date:   Mon, 27 Aug 2018 06:06:20 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Jacek Tomaka <jacek.tomaka@...zta.fm>
Cc:     Jacek Tomaka <jacekt@...eo.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/microcode: allow non-root reading of microcode
 version and processor flags

On Sun, Aug 26, 2018 at 08:23:48PM +0800, Jacek Tomaka wrote:
> I am trying to get microcode version from user space. Reading it
> from /proc/cpuinfo requires greping/awking to extract the bits of
> information that are readily available in microcode/version.

If the only reason is because you find it hard to grep/awk, I won't
take it.

> Any reason why the same piece of information has different access
> permissions, depending on the way it is accessed?

I don't see any particular reason in the original commit which added it:

  9a4b9efa1d39 ("[PATCH] x86 microcode: add sysfs and hotplug support")

except maybe because the reload interface is root-only so making the
others root-only too, made sense.

However, we've made the microcode revision available to everyone in
/proc/cpuinfo, in the meantime, so I guess there's no point in keeping
the version file root-only anymore. And I guess the processor flags too,
while we're at it.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
--