linux-kernel - Re: [qemu64,+smep,+smap] WARNING: CPU: 1 PID: 0 at arch/x86/kernel/cpu/amd.c:220 init

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Date:	Fri, 07 Mar 2014 14:11:50 -0800
From:	"H. Peter Anvin" <hpa@...ux.intel.com>
To:	Dave Jones <davej@...hat.com>, Borislav Petkov <bp@...en8.de>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [qemu64,+smep,+smap] WARNING: CPU: 1 PID: 0 at arch/x86/kernel/cpu/amd.c:220
 init_amd()

On 03/07/2014 02:06 PM, Dave Jones wrote:
> On Fri, Mar 07, 2014 at 10:38:56PM +0100, Borislav Petkov wrote:
> 
>  > * Another option would be if we change the f/m/s of "qemu64" so that
>  > the test doesn't fire.
>  > 
>  > What also makes me wonder is why is this thing even called qemu64?? AMD
>  > family 6 was 32-bit only CPUs so 64 is kinda wrong IMO. I mean, the
>  > kernel code is in "ifdef CONFIG_X86_32" block so "qemu64" is patently
>  > wrong naming.
> 
> Additionally, fam:6 model:6 stepping 3 never existed in the real world afaict.
> I used to keep x86info's stepping db pretty up to date, and that only has knowledge
> of stepping 1 & 2.[*]  Modelling qemu on something from the real world might be
> a better idea than inventing new special cases.
> 
>  > Oh, and the thing has CPUID_EXT2_LM which is also a WTH moment for me.
>  > Paolo, what's going on here?
> 
> Yeah, this is a mess, there should be no family < 0xf with LM set.
> 
> 	Dave

For AMD, at least.  Intel obviously have a bunch of chips with family ==
6 and LM.

Perhaps Fengguang should switch from "qemu64,+smep,+smap" to something
like "Haswell,+smep,+smap" instead for the time being at least?

	-hpa

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