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

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Date:   Mon, 7 Aug 2017 19:50:02 +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 07/08/2017 19:17, Sebastian Rachuj wrote:
>>>
>>> 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.
> 
> Here you are, I hope it helps:

Not much to say, unfortunately.  It's pretty much the same capabilities
as a Prescott/Cedar Mill processor, except that it has MSR bitmaps.  It
also lacks FlexPriority compared to the Conroe I had checked.

It's not great that even the revert patch doesn't apply cleanly---this
is *not* necessarily a boring area of the hypervisor...

Given the rarity of your machine I'm currently leaning towards _not_
reverting the change.  I'll check another non-Xeon Core 2 tomorrow that
is from December 2008 (IIRC).  If that one also lacks vNMI, or if I get
other reports, I suppose I will have to reconsider that.

Paolo