linux-kernel - Re: [PATCH] x86: clear incorrectly forced X86_FEATURE_LAHF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 8 Aug 2009 17:42:46 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Borislav Petkov <petkovbb@...glemail.com>,
	Kevin Winchester <kjwinchester@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Yinghai Lu <yinghai@...nel.org>,
	Andreas Herrmann <andreas.herrmann3@....com>,
	LKML <linux-kernel@...r.kernel.org>, borislav.petkov@....com
Subject: Re: [PATCH] x86: clear incorrectly forced X86_FEATURE_LAHF_LM flag


* Borislav Petkov <petkovbb@...glemail.com> wrote:

> > +
> > +		/*
> > +		 * Some BIOSes incorrectly set this feature, but only
> > +		 * Revision E (with Extended Model = 2) actually supports
> > +		 * it.
> > +		 */
> > +		if (!(level & 0x00020000))
> > +			clear_cpu_cap(c, X86_FEATURE_LAHF_LM);
> 
> let me check this internally next week because it seems that 
> according to the Fam 0xf RevGuide 
> (http://support.amd.com/us/Processor_TechDocs/25759.pdf) erratum 
> 110 applies to atleast 3 CPU revisions with extended model 0x1 
> too.

Ok, mind resending the patch (or dropping it) if you figured that 
out? We need to be careful about restoring CPU erratum workarounds 
that BIOSen install ... these things are very hard to test and easy 
to get wrong.

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/