linux-kernel - Re: kvm_intel fails to load on Conroe CPUs running Linux 4.12

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Message-ID: <596b1df7-7fec-4acf-f19a-67ed4e1ba150@redhat.com>
Date:   Mon, 7 Aug 2017 11:43:56 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sebastian Rachuj <rachus@....de>, rkrcmar@...hat.com,
        tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: kvm_intel fails to load on Conroe CPUs running Linux 4.12

On 06/08/2017 23:23, Sebastian Rachuj wrote:
> On 06.08.2017 23:10, Paolo Bonzini wrote:
>> On 05/08/2017 21:26, Sebastian Rachuj wrote:
>>> Dear linux developers,
>>>
>>> since my upgrade from linux 4.11 to linux 4.12 the "kvm_intel" module
>>> does not load correctly anymore. "Modprobing" the kernel module gives an
>>> Input/Output error. It seems to be related to the CPU architecture and
>>> (to my knowledge) affects Conroe CPUs. I did a bisect and found the
>>> following commit as the guilty one:
>>
>> What is your cpuinfo?  I tested on a Conroe Xeon X3220 (family 6,
>> model 15, stepping 11) when I posted that patch, and it did have virtual
>> NMIs.
> 
> Thank you for looking into the issue. My cpuinfo is as follows:

Looks like Intel was already differentiating virtualization features
across SKUs.  Please run the attached script as root to see what other
things are different (apparently) between non-Xeon and Xeon Conroes.

Thanks,

Paolo

> $ cat /proc/cpuinfo
> processor    : 0
> vendor_id    : GenuineIntel
> cpu family    : 6
> model        : 15
> model name    : Intel(R) Core(TM)2 CPU          6420  @ 2.13GHz
> stepping    : 6
> microcode    : 0xc6
> cpu MHz        : 2128.000
> cache size    : 4096 KB
> physical id    : 0
> siblings    : 2
> core id        : 0
> cpu cores    : 2
> apicid        : 0
> initial apicid    : 0
> fpu        : yes
> fpu_exception    : yes
> cpuid level    : 10
> wp        : yes
> flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
> cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall
> nx lm constant_tsc arch_perfmon pebs bts rep_good nopl cpuid aperfmperf
> pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm
> tpr_shadow dtherm
> bugs        :
> bogomips    : 4275.23
> clflush size    : 64
> cache_alignment    : 64
> address sizes    : 36 bits physical, 48 bits virtual
> power management:
> 
> processor    : 1
> vendor_id    : GenuineIntel
> cpu family    : 6
> model        : 15
> model name    : Intel(R) Core(TM)2 CPU          6420  @ 2.13GHz
> stepping    : 6
> microcode    : 0xc6
> cpu MHz        : 2128.000
> cache size    : 4096 KB
> physical id    : 0
> siblings    : 2
> core id        : 1
> cpu cores    : 2
> apicid        : 1
> initial apicid    : 1
> fpu        : yes
> fpu_exception    : yes
> cpuid level    : 10
> wp        : yes
> flags        : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
> cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall
> nx lm constant_tsc arch_perfmon pebs bts rep_good nopl cpuid aperfmperf
> pni dtes64 monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm lahf_lm
> tpr_shadow dtherm
> bugs        :
> bogomips    : 4275.05
> clflush size    : 64
> cache_alignment    : 64
> address sizes    : 36 bits physical, 48 bits virtual
> power management:


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