Currently include/linux/kvm.h is not considered by make headers_install,
because Kbuild cannot handle " unifdef-$(CONFIG_FOO) += foo.h. This problem
was introduced by

commit fb56dbb31c4738a3918db81fd24da732ce3b4ae6
Author: Avi Kivity
Date: Sun Dec 2 10:50:06 2007 +0200

KVM: Export include/linux/kvm.h only if $ARCH actually supports KVM

Currently, make headers_check barfs due to , which
includes, not existing. Rather than add a zillion s, export kvm.
only if the arch actually supports it.

Signed-off-by: Avi Kivity

which makes this an 2.6.25 regression.

One way of solving the issue is to enhance Kbuild, but Avi and David conviced
me, that changing headers_install is not the way to go. This patch changes
the definition for linux/kvm.h to unifdef-y.

If  unifdef-y is used for linux/kvm.h "make headers_check" will fail on all
architectures without asm/kvm.h. Therefore, this patch also provides
asm/kvm.h on all architectures.

Signed-off-by: Christian Borntraeger
Acked-by: Avi Kivity
Cc: Sam Ravnborg
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds