linux-kernel - Re: [RFC/PATCH 1/5] context tracking: conditionalize guest support based on CONFIG

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Message-ID: <87fw0izxe4.fsf@linaro.org>
Date:	Tue, 26 Feb 2013 11:29:55 -0800
From:	Kevin Hilman <khilman@...aro.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	Mats Liljegren <mats.liljegren@...a.com>,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	linaro-dev@...ts.linaro.org
Subject: Re: [RFC/PATCH 1/5] context tracking: conditionalize guest support based on CONFIG_KVM

Frederic Weisbecker <fweisbec@...il.com> 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 <khilman@...aro.org>
>> ---
>>  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.

Kevin


>From 4444ce39eea21a5fc63b04a711addab2a5c63243 Mon Sep 17 00:00:00 2001
From: Kevin Hilman <khilman@...aro.org>
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 <khilman@...aro.org>
---
 kernel/context_tracking.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 74f68f4..d9c98dd 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -1,5 +1,7 @@
 #include <linux/context_tracking.h>
+#if defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
 #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 defined(CONFIG_KVM) || defined(CONFIG_KVM_MODULE)
 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

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