From: Gleb Natapov <gleb@redhat.com>
To: Bug 1208540 <1208540@bugs.launchpad.net>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [Bug 1208540] [NEW] RDMSR of register 0x345 (IA32_PERF_CAPABILITIES) fails in guest
Date: Mon, 5 Aug 2013 20:43:02 +0300 [thread overview]
Message-ID: <20130805174302.GD15901@redhat.com> (raw)
In-Reply-To: <20130805171730.1100.98667.malonedeb@wampee.canonical.com>
On Mon, Aug 05, 2013 at 05:17:30PM -0000, Jari Ruusu wrote:
> Public bug reported:
>
> I have a problem with qemu when I attempt to configure qemu in a way that
> AES-NI op-codes are enabled in quest. To do that, I have to configure qemu
> to emulate a recent CPU. But that causes a problem, because with recent
> CPUs, guest linux kernel code assumes that RDMSR of register 0x345 works.
> Qemu does not handle that correctly. Qemu does not crash. Guests running
> newer linux kernels always crash on boot with 'general protection fault' on
> RDMSR op-code that attempts to read IA32_PERF_CAPABILITIES. That "crashing"
> linux code works OK on bare metal.
>
This is not QEMU/KVM bug, this is kernel bug since it should not touch
this MSR if cpuid does not have PDCM bit. Compile your guest kernel with
paravirt support (which is a good idea for many reasons) and the crash
will disappear.
--
Gleb.
next prev parent reply other threads:[~2013-08-05 17:43 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-05 17:17 [Qemu-devel] [Bug 1208540] [NEW] RDMSR of register 0x345 (IA32_PERF_CAPABILITIES) fails in guest Jari Ruusu
2013-08-05 17:43 ` Gleb Natapov [this message]
2013-08-09 5:27 ` [Qemu-devel] [Bug 1208540] " Jari Ruusu
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