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[PATCH v3 1/9] clocksource: arm_arch_timer: Gather KVM specific information in a structure

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  [PATCH v3 1/9] clocksource: arm_arch_timer: Gather KVM specific information in a structure Julien Grall <julien.grall@arm.com> - 2016-03-08 12:40 +0100
    Re: [PATCH v3 1/9] clocksource: arm_arch_timer: Gather KVM specific  information in a structure Christoffer Dall <christoffer.dall@linaro.org> - 2016-03-09 04:30 +0100
      Re: [PATCH v3 1/9] clocksource: arm_arch_timer: Gather KVM specific  information in a structure Julien Grall <julien.grall@arm.com> - 2016-03-09 06:40 +0100

#1352912 — [PATCH v3 1/9] clocksource: arm_arch_timer: Gather KVM specific information in a structure

Introduce a structure which are filled up by the arch timer driver and
used by the virtual timer in KVM.

The first member of this structure will be the timecounter. More members
will be added later.

A stub for the new helper isn't introduced because KVM requires the arch
timer for both ARM64 and ARM32.

The function arch_timer_get_timecounter is kept for the time being and
will be dropped in a subsequent patch.

Signed-off-by: Julien Grall <julien.grall@arm.com>

---
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>

    Changes in v3:
        - Rename the patch
        - Move the KVM changes and removal of arch_timer_get_timecounter
        in separate patches.
---
 drivers/clocksource/arm_arch_timer.c | 12 +++++++++---
 include/clocksource/arm_arch_timer.h |  5 +++++
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index ffe9d1c..b7ab588 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -456,11 +456,16 @@ static struct cyclecounter cyclecounter = {
 	.mask	= CLOCKSOURCE_MASK(56),
 };
 
-static struct timecounter timecounter;
+static struct arch_timer_kvm_info arch_timer_kvm_info;
+
+struct arch_timer_kvm_info *arch_timer_get_kvm_info(void)
+{
+	return &arch_timer_kvm_info;
+}
 
 struct timecounter *arch_timer_get_timecounter(void)
 {
-	return &timecounter;
+	return &arch_timer_kvm_info.timecounter;
 }
 
 static void __init arch_counter_register(unsigned type)
@@ -488,7 +493,8 @@ static void __init arch_counter_register(unsigned type)
 	clocksource_register_hz(&clocksource_counter, arch_timer_rate);
 	cyclecounter.mult = clocksource_counter.mult;
 	cyclecounter.shift = clocksource_counter.shift;
-	timecounter_init(&timecounter, &cyclecounter, start_count);
+	timecounter_init(&arch_timer_kvm_info.timecounter,
+			 &cyclecounter, start_count);
 
 	/* 56 bits minimum, so we assume worst case rollover */
 	sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
index 25d0914..9101ed6b 100644
--- a/include/clocksource/arm_arch_timer.h
+++ b/include/clocksource/arm_arch_timer.h
@@ -49,11 +49,16 @@ enum arch_timer_reg {
 
 #define ARCH_TIMER_EVT_STREAM_FREQ	10000	/* 100us */
 
+struct arch_timer_kvm_info {
+	struct timecounter timecounter;
+};
+
 #ifdef CONFIG_ARM_ARCH_TIMER
 
 extern u32 arch_timer_get_rate(void);
 extern u64 (*arch_timer_read_counter)(void);
 extern struct timecounter *arch_timer_get_timecounter(void);
+extern struct arch_timer_kvm_info *arch_timer_get_kvm_info(void);
 
 #else
 
-- 
1.9.1

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#1353761 — Re: [PATCH v3 1/9] clocksource: arm_arch_timer: Gather KVM specific information in a structure

On Tue, Mar 08, 2016 at 11:29:25AM +0000, Julien Grall wrote:
> Introduce a structure which are filled up by the arch timer driver and
> used by the virtual timer in KVM.
> 
> The first member of this structure will be the timecounter. More members
> will be added later.
> 
> A stub for the new helper isn't introduced because KVM requires the arch
> timer for both ARM64 and ARM32.
> 
> The function arch_timer_get_timecounter is kept for the time being and
> will be dropped in a subsequent patch.
> 
> Signed-off-by: Julien Grall <julien.grall@arm.com>
> 
> ---
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Marc Zyngier <marc.zyngier@arm.com>
> 
>     Changes in v3:
>         - Rename the patch
>         - Move the KVM changes and removal of arch_timer_get_timecounter
>         in separate patches.
> ---
>  drivers/clocksource/arm_arch_timer.c | 12 +++++++++---
>  include/clocksource/arm_arch_timer.h |  5 +++++
>  2 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index ffe9d1c..b7ab588 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -456,11 +456,16 @@ static struct cyclecounter cyclecounter = {
>  	.mask	= CLOCKSOURCE_MASK(56),
>  };
>  
> -static struct timecounter timecounter;
> +static struct arch_timer_kvm_info arch_timer_kvm_info;
> +
> +struct arch_timer_kvm_info *arch_timer_get_kvm_info(void)

borderline bikeshedding question:

does it make sense that the info the arch timer code exports is labeled
to be kvm-specific?  In other words, could we imagine another subsystem
using this timer info some time and is there a more generic term that
would be more appropriate?


otherwise it looks fine to me.

-Christoffer

> +{
> +	return &arch_timer_kvm_info;
> +}
>  
>  struct timecounter *arch_timer_get_timecounter(void)
>  {
> -	return &timecounter;
> +	return &arch_timer_kvm_info.timecounter;
>  }
>  
>  static void __init arch_counter_register(unsigned type)
> @@ -488,7 +493,8 @@ static void __init arch_counter_register(unsigned type)
>  	clocksource_register_hz(&clocksource_counter, arch_timer_rate);
>  	cyclecounter.mult = clocksource_counter.mult;
>  	cyclecounter.shift = clocksource_counter.shift;
> -	timecounter_init(&timecounter, &cyclecounter, start_count);
> +	timecounter_init(&arch_timer_kvm_info.timecounter,
> +			 &cyclecounter, start_count);
>  
>  	/* 56 bits minimum, so we assume worst case rollover */
>  	sched_clock_register(arch_timer_read_counter, 56, arch_timer_rate);
> diff --git a/include/clocksource/arm_arch_timer.h b/include/clocksource/arm_arch_timer.h
> index 25d0914..9101ed6b 100644
> --- a/include/clocksource/arm_arch_timer.h
> +++ b/include/clocksource/arm_arch_timer.h
> @@ -49,11 +49,16 @@ enum arch_timer_reg {
>  
>  #define ARCH_TIMER_EVT_STREAM_FREQ	10000	/* 100us */
>  
> +struct arch_timer_kvm_info {
> +	struct timecounter timecounter;
> +};
> +
>  #ifdef CONFIG_ARM_ARCH_TIMER
>  
>  extern u32 arch_timer_get_rate(void);
>  extern u64 (*arch_timer_read_counter)(void);
>  extern struct timecounter *arch_timer_get_timecounter(void);
> +extern struct arch_timer_kvm_info *arch_timer_get_kvm_info(void);
>  
>  #else
>  
> -- 
> 1.9.1
> 

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#1353818 — Re: [PATCH v3 1/9] clocksource: arm_arch_timer: Gather KVM specific information in a structure

Hi Christoffer,

On 09/03/2016 10:23, Christoffer Dall wrote:
> On Tue, Mar 08, 2016 at 11:29:25AM +0000, Julien Grall wrote:
>> -static struct timecounter timecounter;
>> +static struct arch_timer_kvm_info arch_timer_kvm_info;
>> +
>> +struct arch_timer_kvm_info *arch_timer_get_kvm_info(void)
>
> borderline bikeshedding question:
>
> does it make sense that the info the arch timer code exports is labeled
> to be kvm-specific?  In other words, could we imagine another subsystem
> using this timer info some time and is there a more generic term that
> would be more appropriate?

I can't see any other usage. I would keep the function name KVM specific 
until someone really need similar information.

Cheers,

-- 
Julien Grall

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