Subject: [RFC/PATCH 1/5] context tracking: conditionalize guest support based on CONFIG_KVM

From: [email-masked] (Kevin Hilman)
Date: Wed, 27 Feb 2013 06:24:03 -0800

Namhyung Kim <[email-masked]> writes:

> 2013-02-26 (?), 11:29 -0800, Kevin Hilman:
>> Frederic Weisbecker <[email-masked]> writes:
>> 
>> > On Wed, Feb 20, 2013 at 11:41:38AM -0800, Kevin Hilman wrote:
>> >> So that it can build on !KVM systems too.
>> >> 
>> >> Signed-off-by: Kevin Hilman <[email-masked]>
>> >> ---
>> >>  kernel/context_tracking.c | 4 ++++
>> >>  1 file changed, 4 insertions(+)
>> >> 
>> >> diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
>> >> index 74f68f4..6fe96b1 100644
>> >> --- a/kernel/context_tracking.c
>> >> +++ b/kernel/context_tracking.c
>> >> @@ -1,5 +1,7 @@
>> >>  #include <linux/context_tracking.h>
>> >> +#ifdef CONFIG_KVM
>> >>  #include <linux/kvm_host.h>
>> >> +#endif
>> >
>> > The header should take care of the off-case, no need to ifdef its inclusion.
>> 
>> In their current form, the headers will not build on platforms without
>> KVM support.  For example, these platforms (like ARM) don't even have
>> <asm/kvm.h> or <asm/kvm_host.h>.
>> 
>> >>  #include <linux/rcupdate.h>
>> >>  #include <linux/sched.h>
>> >>  #include <linux/hardirq.h>
>> >> @@ -62,6 +64,7 @@ void user_exit(void)
>> >>  	local_irq_restore(flags);
>> >>  }
>> >>  
>> >> +#ifdef CONFIG_KVM
>> >>  void guest_enter(void)
>> >>  {
>> >>  	if (vtime_accounting_enabled())
>> >> @@ -79,6 +82,7 @@ void guest_exit(void)
>> >>  		__guest_exit();
>> >>  }
>> >>  EXPORT_SYMBOL_GPL(guest_exit);
>> >> +#endif
>> >
>> > Kvm might be built as a module so we can't actually do this unfortunately.
>> 
>> Ah, right.  How bout using 
>> 
>> #if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
>> 
>> for both conditionals above?  Updated patch below.
>
> This is what IS_ENABLED(CONFIG_KVM) is for.

Right, updated patch below.

Kevin

>>From 61e35f069a64c03a2bce348487d41072aeb9f36b Mon Sep 17 00:00:00 2001
From: Kevin Hilman <[email-masked]>
Date: Thu, 14 Feb 2013 10:17:37 -0800
Subject: [PATCH] context tracking: conditionalize guest support based on
 CONFIG_KVM

So that it can build on !KVM systems too.

Signed-off-by: Kevin Hilman <[email-masked]>
---
 kernel/context_tracking.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 74f68f4..fda6cd6 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -1,5 +1,7 @@
 #include <linux/context_tracking.h>
+#if IS_ENABLED(CONFIG_KVM)
 #include <linux/kvm_host.h>
+#endif
 #include <linux/rcupdate.h>
 #include <linux/sched.h>
 #include <linux/hardirq.h>
@@ -62,6 +64,7 @@ void user_exit(void)
 	local_irq_restore(flags);
 }
 
+#if IS_ENABLED(CONFIG_KVM)
 void guest_enter(void)
 {
 	if (vtime_accounting_enabled())
@@ -79,6 +82,7 @@ void guest_exit(void)
 		__guest_exit();
 }
 EXPORT_SYMBOL_GPL(guest_exit);
+#endif
 
 void context_tracking_task_switch(struct task_struct *prev,
 			     struct task_struct *next)
-- 
1.8.1.2