linux-kernel - Re: [PATCH 1/2] x86, microcode: Do Intel microcode revision check signed

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Message-ID: <52A74AAE.70804@zytor.com>
Date:	Tue, 10 Dec 2013 09:09:02 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Andi Kleen <andi@...stfloor.org>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	linux-kernel@...r.kernel.org, x86@...nel.org,
	Andi Kleen <ak@...ux.intel.com>
Subject: Re: [PATCH 1/2] x86, microcode: Do Intel microcode revision check
 signed

On 12/10/2013 07:55 AM, Andi Kleen wrote:
> On Tue, Dec 10, 2013 at 10:30:00AM -0500, Konrad Rzeszutek Wilk wrote:
>> On Fri, Dec 06, 2013 at 01:04:02PM -0800, Andi Kleen wrote:
>>> From: Andi Kleen <ak@...ux.intel.com>
>>>
>>> The Intel SDM Vol 3 9.11.1 Microcode update states that
>>> the update revision field is signed. However we do the comparison
>>> unsigned, as the comparison gets promoted.
>>>
>>> Use a cast to really do a signed comparison of the microcode
>>> revision.
>>
>> Why not just update the struct?
> 
> It would need updating various printks I think. So I chose the simpler cast,
> as that already solves the comparison problem.
> 
> -Andi
> 

Updating the printks sounds like the right thing, too.

	-hpa

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