kvm_intel fails to load on Conroe CPUs running Linux 4.12

[Sebastian Rachuj]

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@xxxxxxxxxx>
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@xxxxxxxxxx>

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