Re: [PATCH] KVM: allow host header to be included even for !CONFIG_KVM

[Scott Wood <scottwood@freescale.com>]

On 03/14/2013 07:13:46 PM, Kevin Hilman wrote:
> The new context tracking subsystem unconditionally includes kvm_host.h
> headers for the guest enter/exit macros.  This causes a compile
> failure when KVM is not enabled.
> 
> Fix by adding an IS_ENABLED(CONFIG_KVM) check to kvm_host so it can
> be included/compiled even when KVM is not enabled.
> 
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Signed-off-by: Kevin Hilman <khilman@linaro.org>
> ---
> Applies on v3.9-rc2
> 
>  include/linux/kvm_host.h | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)

This broke the PPC non-KVM build, which was relying on stub functions  
in kvm_ppc.h, which relies on "struct vcpu" in kvm_host.h.

Why can't the entirety kvm_host.h be included regardless of CONFIG_KVM,  
just like most other feature-specific headers?  Why can't the if/else  
just go around the functions that you want to stub out for non-KVM  
builds?

-Scott