On 29/07/2017 14:35, Denis Plotnikov wrote:
> The parameter is a pointer which is used to store cycles stamp value
> used for time calulation on pvclock reading.
>
> This is a part of the work aiming to move to a more simple scheme of
> masterclock related values calculation in KVM.
>
> Signed-off-by: Denis Plotnikov <dplotnikov@xxxxxxxxxxxxx>
> ---
> arch/x86/include/asm/pvclock.h | 2 +-
> arch/x86/kernel/kvmclock.c | 2 +-
> arch/x86/kernel/pvclock.c | 12 +++++++++---
> arch/x86/xen/time.c | 2 +-
> 4 files changed, 12 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
> index 448cfe1..147b411 100644
> --- a/arch/x86/include/asm/pvclock.h
> +++ b/arch/x86/include/asm/pvclock.h
> @@ -14,7 +14,7 @@ static inline struct pvclock_vsyscall_time_info *pvclock_pvti_cpu0_va(void)
> #endif
>
> /* some helper functions for xen and kvm pv clock sources */
> -u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src);
> +u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src, u64 *cycles);
> u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src);
> void pvclock_set_flags(u8 flags);
> unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src);
> diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
> index d889676..f5cfc5d 100644
> --- a/arch/x86/kernel/kvmclock.c
> +++ b/arch/x86/kernel/kvmclock.c
> @@ -91,7 +91,7 @@ static u64 kvm_clock_read(void)
> preempt_disable_notrace();
> cpu = smp_processor_id();
> src = &hv_clock[cpu].pvti;
> - ret = pvclock_clocksource_read(src);
> + ret = pvclock_clocksource_read(src, NULL);
> preempt_enable_notrace();
> return ret;
> }
> diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
> index 5c3f6d6..a2c554a 100644
> --- a/arch/x86/kernel/pvclock.c
> +++ b/arch/x86/kernel/pvclock.c
> @@ -73,19 +73,24 @@ u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src)
> return flags & valid_flags;
> }
>
> -u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src)
> +u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src, u64 *cycles)
> {
> unsigned version;
> u64 ret;
> u64 last;
> u8 flags;
> + u64 tsc;
>
> do {
> version = pvclock_read_begin(src);
> - ret = __pvclock_read_cycles(src, rdtsc_ordered());
> + tsc = rdtsc_ordered();
> + ret = __pvclock_read_cycles(src, tsc);
> flags = src->flags;
> } while (pvclock_read_retry(src, version));
>
> + if (cycles)
> + *cycles = tsc;
> +
> if (unlikely((flags & PVCLOCK_GUEST_STOPPED) != 0)) {
> src->flags &= ~PVCLOCK_GUEST_STOPPED;
> pvclock_touch_watchdogs();
> @@ -136,7 +141,8 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock,
> rmb(); /* fetch time before checking version */
> } while ((wall_clock->version & 1) || (version != wall_clock->version));
>
> - delta = pvclock_clocksource_read(vcpu_time); /* time since system boot */
> + /* time since system boot */
> + delta = pvclock_clocksource_read(vcpu_time, NULL);
> delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec;
>
> now.tv_nsec = do_div(delta, NSEC_PER_SEC);
> diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
> index 1ecb05d..145ac9a 100644
> --- a/arch/x86/xen/time.c
> +++ b/arch/x86/xen/time.c
> @@ -46,7 +46,7 @@ u64 xen_clocksource_read(void)
>
> preempt_disable_notrace();
> src = &__this_cpu_read(xen_vcpu)->time;
> - ret = pvclock_clocksource_read(src);
> + ret = pvclock_clocksource_read(src, NULL);
> preempt_enable_notrace();
> return ret;
> }
>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
