diff mbox

KVM: allow host header to be included even for !CONFIG_KVM

Message ID 878v5ggv3s.fsf@linaro.org (mailing list archive)
State New, archived
Headers show

Commit Message

Kevin Hilman March 22, 2013, 12:02 a.m. UTC
Gleb Natapov <gleb@redhat.com> writes:

> On Thu, Mar 21, 2013 at 02:33:13PM -0500, Scott Wood wrote:
>> On 03/21/2013 02:16:00 PM, Gleb Natapov wrote:
>> >On Thu, Mar 21, 2013 at 01:42:34PM -0500, Scott Wood wrote:
>> >> On 03/21/2013 09:27:14 AM, Kevin Hilman wrote:
>> >> >Gleb Natapov <gleb@redhat.com> writes:
>> >> >
>> >> >> On Wed, Mar 20, 2013 at 06:58:41PM -0500, Scott Wood wrote:
>> >> >>> 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?
>> >> >>>
>> >> >> Kevin,
>> >> >>
>> >> >>  What compilation failure this patch fixes? I presume
>> >something ARM
>> >> >> related.
>> >> >
>> >> >Not specficially ARM related, but more context tracking related
>> >since
>> >> >kernel/context_tracking.c pulls in kvm_host.h, which attempts to
>> >> >pull in
>> >> ><asm/kvm*.h> which may not exist on some platforms.
>> >> >
>> >> >At least for ARM, KVM support was added in v3.9 so this patch can
>> >> >probably be dropped since the non-KVM builds on ARM now work.
>> >But any
>> >> >platform without the <asm/kvm*.h> will still be broken when
>> >trying to
>> >> >build the context tracker.
>> >>
>> >> Maybe other platforms should get empty asm/kvm*.h files.  Is there
>> >> anything from those files that the linux/kvm*.h headers need to
>> >> build?
>> >>
>> >arch things. kvm_vcpu_arch, kvm_arch_memory_slot, kvm_arch etc.
>> 
>> Could define them as empty structs.
>> 
> Isn't is simpler for kernel/context_tracking.c to define empty
> __guest_enter()/__guest_exit() if !CONFIG_KVM.

I proposed something like that in an earlier version but Frederic asked
me to propose a fix to the KVM headers instead.

Just in case fixing the context tracking subsystem is preferred, 
the patch below fixes the problem also.

Kevin

From f22995a262144d0d61705fa72134694d911283eb Mon Sep 17 00:00:00 2001
From: Kevin Hilman <khilman@linaro.org>
Date: Thu, 21 Mar 2013 16:57:14 -0700
Subject: [PATCH] context_tracking: fix !CONFIG_KVM compile: add stub guest
 enter/exit

When KVM is not enabled, or not available on a platform, the KVM
headers should not be included.  Instead, just define stub
__guest_[enter|exit] functions.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Kevin Hilman <khilman@linaro.org>
---
 kernel/context_tracking.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Gleb Natapov March 24, 2013, 10:21 a.m. UTC | #1
On Thu, Mar 21, 2013 at 05:02:15PM -0700, Kevin Hilman wrote:
> Gleb Natapov <gleb@redhat.com> writes:
> 
> > On Thu, Mar 21, 2013 at 02:33:13PM -0500, Scott Wood wrote:
> >> On 03/21/2013 02:16:00 PM, Gleb Natapov wrote:
> >> >On Thu, Mar 21, 2013 at 01:42:34PM -0500, Scott Wood wrote:
> >> >> On 03/21/2013 09:27:14 AM, Kevin Hilman wrote:
> >> >> >Gleb Natapov <gleb@redhat.com> writes:
> >> >> >
> >> >> >> On Wed, Mar 20, 2013 at 06:58:41PM -0500, Scott Wood wrote:
> >> >> >>> 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?
> >> >> >>>
> >> >> >> Kevin,
> >> >> >>
> >> >> >>  What compilation failure this patch fixes? I presume
> >> >something ARM
> >> >> >> related.
> >> >> >
> >> >> >Not specficially ARM related, but more context tracking related
> >> >since
> >> >> >kernel/context_tracking.c pulls in kvm_host.h, which attempts to
> >> >> >pull in
> >> >> ><asm/kvm*.h> which may not exist on some platforms.
> >> >> >
> >> >> >At least for ARM, KVM support was added in v3.9 so this patch can
> >> >> >probably be dropped since the non-KVM builds on ARM now work.
> >> >But any
> >> >> >platform without the <asm/kvm*.h> will still be broken when
> >> >trying to
> >> >> >build the context tracker.
> >> >>
> >> >> Maybe other platforms should get empty asm/kvm*.h files.  Is there
> >> >> anything from those files that the linux/kvm*.h headers need to
> >> >> build?
> >> >>
> >> >arch things. kvm_vcpu_arch, kvm_arch_memory_slot, kvm_arch etc.
> >> 
> >> Could define them as empty structs.
> >> 
> > Isn't is simpler for kernel/context_tracking.c to define empty
> > __guest_enter()/__guest_exit() if !CONFIG_KVM.
> 
> I proposed something like that in an earlier version but Frederic asked
> me to propose a fix to the KVM headers instead.
> 
> Just in case fixing the context tracking subsystem is preferred, 
> the patch below fixes the problem also.
> 
The patch that broke PPC build was reverted. Frederic can you get the
patch below?

> Kevin
> 
> >From f22995a262144d0d61705fa72134694d911283eb Mon Sep 17 00:00:00 2001
> From: Kevin Hilman <khilman@linaro.org>
> Date: Thu, 21 Mar 2013 16:57:14 -0700
> Subject: [PATCH] context_tracking: fix !CONFIG_KVM compile: add stub guest
>  enter/exit
> 
> When KVM is not enabled, or not available on a platform, the KVM
> headers should not be included.  Instead, just define stub
> __guest_[enter|exit] functions.
> 
> Cc: Frederic Weisbecker <fweisbec@gmail.com>
> Signed-off-by: Kevin Hilman <khilman@linaro.org>
> ---
>  kernel/context_tracking.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
> index 65349f0..64b0f80 100644
> --- a/kernel/context_tracking.c
> +++ b/kernel/context_tracking.c
> @@ -15,12 +15,18 @@
>   */
>  
>  #include <linux/context_tracking.h>
> -#include <linux/kvm_host.h>
>  #include <linux/rcupdate.h>
>  #include <linux/sched.h>
>  #include <linux/hardirq.h>
>  #include <linux/export.h>
>  
> +#if IS_ENABLED(CONFIG_KVM)
> +#include <linux/kvm_host.h>
> +#else
> +#define __guest_enter()
> +#define __guest_exit()
> +#endif
> +
>  DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
>  #ifdef CONFIG_CONTEXT_TRACKING_FORCE
>  	.active = true,
> -- 
> 1.8.2

--
			Gleb.
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diff mbox

Patch

diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c
index 65349f0..64b0f80 100644
--- a/kernel/context_tracking.c
+++ b/kernel/context_tracking.c
@@ -15,12 +15,18 @@ 
  */
 
 #include <linux/context_tracking.h>
-#include <linux/kvm_host.h>
 #include <linux/rcupdate.h>
 #include <linux/sched.h>
 #include <linux/hardirq.h>
 #include <linux/export.h>
 
+#if IS_ENABLED(CONFIG_KVM)
+#include <linux/kvm_host.h>
+#else
+#define __guest_enter()
+#define __guest_exit()
+#endif
+
 DEFINE_PER_CPU(struct context_tracking, context_tracking) = {
 #ifdef CONFIG_CONTEXT_TRACKING_FORCE
 	.active = true,