linux-kernel - Re: KVM warning about uncertified CPU for SMP for AMD model 2, stepping3

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Message-Id: <201003301825.57229.iggy@theiggy.com>
Date:	Tue, 30 Mar 2010 18:25:56 -0500
From:	Brian Jackson <iggy@...iggy.com>
To:	Jiri Kosina <jkosina@...e.cz>
Cc:	Ingo Molnar <mingo@...e.hu>, Andi Kleen <andi@...stfloor.org>,
	Avi Kivity <avi@...hat.com>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	Joerg Roedel <joerg.roedel@....com>,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: KVM warning about uncertified CPU for SMP for AMD model 2, stepping3

On Tuesday 30 March 2010 06:03:02 pm Jiri Kosina wrote:
> Hi,
> 
> booting 32bit guest on 32bit host on AMD system gives me the following
> warning when KVM is instructed to boot as SMP:


This has been discussed before (fairly recently). Subject was "tainted Linux 
kernel in default SMP QEMU/KVM guests". A few solutions were mentioned, so I 
won't bother boring everyone with repeating them.



> 
> 
> 
> CPU0: AMD QEMU Virtual CPU version 0.9.1 stepping 03
> Booting Node   0, Processors  #1
> Initializing CPU#1
> Leaving ESR disabled.
> Mapping cpu 1 to node 0
> ------------[ cut here ]------------
> WARNING: at linux-2.6.32/arch/x86/kernel/cpu/amd.c:187
> init_amd_k7+0x178/0x187() Hardware name:
> WARNING: This combination of AMD processors is not suitable for SMP.
> Modules linked in:
> Pid: 0, comm: swapper Not tainted 2.6.32.9-0.5-pae #1
> Call Trace:
>  [<c02069a1>] try_stack_unwind+0x1b1/0x1f0
>  [<c020596f>] dump_trace+0x3f/0xe0
>  [<c02065ab>] show_trace_log_lvl+0x4b/0x60
>  [<c02065d8>] show_trace+0x18/0x20
>  [<c052dc19>] dump_stack+0x6d/0x74
>  [<c023ebbf>] warn_slowpath_common+0x6f/0xd0
>  [<c023ec6b>] warn_slowpath_fmt+0x2b/0x30
>  [<c052875c>] init_amd_k7+0x178/0x187
>  [<c052896f>] init_amd+0x138/0x279
>  [<c0527d74>] identify_cpu+0xc2/0x223
>  [<c0527ee1>] identify_secondary_cpu+0xc/0x1a
>  [<c052b3bc>] smp_callin+0xd4/0x1a1
>  [<c052b493>] start_secondary+0xa/0xe7
> 
> 
> 
> The virtual CPU identifies itself as cpu family 6, model 2, stepping 3 in
> /proc/cpuinfo.
> 
> Model 2 is indeed not handled by amd_k7_smp_check() and thus this warning
> is spit out.
> 
> Is that correct? Model 2 refers to Pluto/Orion (K75) if I remember
> correctly, right? That one is not oficially certified for SMP by AMD?
> 
> If it is not, maybe KVM should better emulate different CPU for
> SMP-enabled configurations, right?
> On the other hand, if it is certified (I have no idea), amd_k7_smp_check()
> should handle this model properly.
> 
> Thanks,
--
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