Re: [PATCH v4 1/9] clocksource: arm_arch_timer: Gather KVM specific information in a structure

Daniel Lezcano
2016-03-29T17:14:16Z

On 03/24/2016 06:53 PM, 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 5152b38..62bdfe7 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -468,11 +468,16 @@ static struct cyclecounter cyclecounter = {
> .mask = CLOCKSOURCE_MASK(56),
> };
>
> -static struct timecounter timecounter;
> +static struct arch_timer_kvm_info arch_timer_kvm_info;

This structure is statically defined in this subsystem but not used in
this file and a couple of a accessors is added to let another subsystem
to access it.

That sounds there is something wrong here with the design of the current
code, virt/phys are mixed.

It isn't possible to split the virt/phys timer code respectively in
virt/kvm/arm/arch_timer.c and drivers/clocksource/arm_arch_timer.c ?

At least, 'struct arch_timer_kvm_info' should belong to
virt/kvm/arm/arch_timer.c.

> +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)
> @@ -500,7 +505,8 @@ 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
>
>

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