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Date: Thu, 13 Feb 2014 06:55:33 -0800
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Fengguang Wu <fengguang.wu@intel.com>, kvm <kvm@vger.kernel.org>
CC: LKML <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [qemu64,+smep,+smap] Kernel panic - not syncing: No working init
 found.
References: <20140213124550.GA30497@localhost>
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On 02/13/2014 04:45 AM, Fengguang Wu wrote:
> Greetings,
> 
> I find that when running
> 
>         qemu-system-x86_64 -cpu qemu64,+smep,+smap
> 
> Some kernels will 100% produce this error, where the error code
> -13,-14 are -EACCES and -EFAULT:
> 
> Any ideas?
> 

I notice this is a non-SMAP kernel:

# CONFIG_X86_SMAP is not set

If the kernel turns on SMAP in CR4 even though SMAP isn't enabled in the
kernel, that is a kernel bug.  If Qemu enforces SMAP even if it is
turned off in CR4, that would be a Qemu bug.  I have reproduced the
failure locally and an am considering both possibilities now.

	-hpa