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

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Message-ID: <trinity-e2afbfd4-1cb1-4052-a107-3815243fb67e-1501961202650@3capp-webde-bs09>
Date:   Sat, 5 Aug 2017 21:26:42 +0200
From:   "Sebastian Rachuj" <Rachus@....de>
To:     pbonzini@...hat.com, 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: kvm_intel fails to load on Conroe CPUs running Linux 4.12

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:

commit 2c82878b0cb38fd516fd612c67852a6bbf282003
Author: Paolo Bonzini <pbonzini@...hat.com>
Date:   Mon Mar 27 14:37:28 2017 +0200

    KVM: VMX: require virtual NMI support

    Virtual NMIs are only missing in Prescott and Yonah chips.  Both are obsolete
    for virtualization usage---Yonah is 32-bit only even---so drop vNMI emulation.

    Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>

Since the commit message only mentions Prescott and Yonah chips, I wanted to ask whether this commit is also intended to affect Conroe CPUs (which are probably still a bit more widespread). Do you see a solution to bring back support for Conroe chips?

Thank you for your hard work on the kernel!

Best regards,
Sebastian Rachuj