linux-kernel - Re: [PATCH] x86/kernel/cpu/amd.c: don't apply the 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]

Message-ID: <20170712134706.GA20584@nazgul.tnic>
Date:   Wed, 12 Jul 2017 15:47:06 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Mikulas Patocka <mpatocka@...hat.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/kernel/cpu/amd.c: don't apply the lahf_lm workaround
 in a hypervisor

On Wed, Jul 12, 2017 at 03:19:56AM -0400, Mikulas Patocka wrote:
> When I start a virtual machine, kvm complains about accesses to an unknown
> MSR ("vcpu0 unhandled rdmsr: 0xc001100d"). This is caused by the code in
> init_amd_k8 that tries to work around a BIOS bug that incorrectly sets
> lahf_lm.

No need - there are a lot of qemu configurations which cause the
unhandled MSR warning so no need to pollute the kernel unnecessarily.
The warning is harmless at that.

-- 
Regards/Gruss,
    Boris.

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