[PATCH v2 0/3] Add a unified parameter "nopvspin"

[Zhenzhong Duan <zhenzhong.duan@xxxxxxxxxx>]

There are cases folks want to disable spinlock optimization for
debug/test purpose. Xen and hyperv already have parameters "xen_nopvspin"
and "hv_nopvspin" to support that, but kvm doesn't.

The first patch adds that feature to KVM guest with "nopvspin".

For compatibility reason original parameters "xen_nopvspin" and
"hv_nopvspin" are retained and marked obsolete.

v2:
PATCH1: pick the print code change into seperate PATCH2,
        updated patch description             [Vitaly Kuznetsov]
PATCH2: new patch with print code change      [Vitaly Kuznetsov]
PATCH3: add Reviewed-by                       [Juergen Gross]

Thanks
Zhenzhong