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

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Message-ID: <20140307055035.GA5230@localhost>
Date:	Fri, 7 Mar 2014 13:50:35 +0800
From:	Fengguang Wu <fengguang.wu@...el.com>
To:	"H. Peter Anvin" <hpa@...ux.intel.com>
Cc:	Andreas Herrmann <andreas.herrmann3@....com>,
	Ingo Molnar <mingo@...e.hu>,
	Borislav Petkov <borislav.petkov@....com>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [qemu64,+smep,+smap] WARNING: CPU: 1 PID: 0 at
 arch/x86/kernel/cpu/amd.c:220 init_amd()

On Thu, Mar 06, 2014 at 09:03:50PM -0800, H. Peter Anvin wrote:
> On 03/06/2014 05:58 PM, Fengguang Wu wrote:
> > Hi all,
> > 
> > I find the below WARNING shows up only in
> > 
> >         qemu-system-x86_64 -cpu qemu64,+smep,+smap
> > 
> 
> Yes, it is because Qemu doesn't show the AMD-specific SMP CPUID bit.
> It's harmless in that sense.
> 
> Unfortunately these things are hard to fix in Qemu.

OK. As an alternative, is it possible to pass one of the below CPUID flags in
the Qemu command line, so as to quiet the warning?

% qemu-system-x86_64 -cpu help
x86           qemu64  QEMU Virtual CPU version 1.6.1                  
x86           phenom  AMD Phenom(tm) 9550 Quad-Core Processor         
x86         core2duo  Intel(R) Core(TM)2 Duo CPU     T7700  @ 2.40GHz 
x86            kvm64  Common KVM processor                            
x86           qemu32  QEMU Virtual CPU version 1.6.1                  
x86            kvm32  Common 32-bit KVM processor                     
x86          coreduo  Genuine Intel(R) CPU           T2600  @ 2.16GHz 
x86              486                                                  
x86          pentium                                                  
x86         pentium2                                                  
x86         pentium3                                                  
x86           athlon  QEMU Virtual CPU version 1.6.1                  
x86             n270  Intel(R) Atom(TM) CPU N270   @ 1.60GHz          
x86           Conroe  Intel Celeron_4x0 (Conroe/Merom Class Core 2)   
x86           Penryn  Intel Core 2 Duo P9xxx (Penryn Class Core 2)    
x86          Nehalem  Intel Core i7 9xx (Nehalem Class Core i7)       
x86         Westmere  Westmere E56xx/L56xx/X56xx (Nehalem-C)          
x86      SandyBridge  Intel Xeon E312xx (Sandy Bridge)                
x86          Haswell  Intel Core Processor (Haswell)                  
x86       Opteron_G1  AMD Opteron 240 (Gen 1 Class Opteron)           
x86       Opteron_G2  AMD Opteron 22xx (Gen 2 Class Opteron)          
x86       Opteron_G3  AMD Opteron 23xx (Gen 3 Class Opteron)          
x86       Opteron_G4  AMD Opteron 62xx class CPU                      
x86       Opteron_G5  AMD Opteron 63xx class CPU                      
x86             host  KVM processor with all supported host features (only available in KVM mode)

Recognized CPUID flags:
  pbe ia64 tm ht ss sse2 sse fxsr mmx acpi ds clflush pn pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de vme fpu
  hypervisor rdrand f16c avx osxsave xsave aes tsc-deadline popcnt movbe x2apic sse4.2|sse4_2 sse4.1|sse4_1 dca pcid pdcm xtpr cx16 fma cid ssse3 tm2 est smx vmx ds_cpl monitor dtes64 pclmulqdq|pclmuldq pni|sse3
  smap adx rdseed rtm invpcid erms bmi2 smep avx2 hle bmi1 fsgsbase
  3dnow 3dnowext lm|i64 rdtscp pdpe1gb fxsr_opt|ffxsr mmxext nx|xd syscall
  perfctr_nb perfctr_core topoext tbm nodeid_msr tce fma4 lwp wdt skinit xop ibs osvw 3dnowprefetch misalignsse sse4a abm cr8legacy extapic svm cmp_legacy lahf_lm
  pmm-en pmm phe-en phe ace2-en ace2 xcrypt-en xcrypt xstore-en xstore
  kvm_pv_eoi kvm_steal_time kvm_asyncpf kvmclock kvm_mmu kvm_nopiodelay kvmclock
  pfthreshold pause_filter decodeassists flushbyasid vmcb_clean tsc_scale nrip_save svm_lock lbrv npt

Thanks,
Fengguang
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