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SubjectRe: [PATCH 07/10] clocksource/drivers/hyper-v: Handle vDSO differences inline
On Wed, Jan 27, 2021 at 12:23:42PM -0800, Michael Kelley wrote:
> While the driver for the Hyper-V Reference TSC and STIMERs is architecture
> neutral, vDSO is implemented for x86/x64, but not for ARM64. Current code
> calls into utility functions under arch/x86 (and coming, under arch/arm64)
> to handle the difference.
>
> Change this approach to handle the difference inline based on whether
> VDSO_CLOCK_MODE_HVCLOCK is present. The new approach removes code under
> arch/* since the difference is tied more to the specifics of the Linux
> implementation than to the architecture.
>
> No functional change.
>
> Signed-off-by: Michael Kelley <mikelley@microsoft.com>

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>

Regards,
Boqun

> ---
> arch/x86/include/asm/mshyperv.h | 4 ----
> drivers/clocksource/hyperv_timer.c | 10 ++++++++--
> 2 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index 4d3e0c5..ed9dc56 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -27,10 +27,6 @@ static inline u64 hv_get_register(unsigned int reg)
> return value;
> }
>
> -#define hv_set_clocksource_vdso(val) \
> - ((val).vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK)
> -#define hv_enable_vdso_clocksource() \
> - vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK);
> #define hv_get_raw_timer() rdtsc_ordered()
>
> /*
> diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
> index 9425308..9cee6db 100644
> --- a/drivers/clocksource/hyperv_timer.c
> +++ b/drivers/clocksource/hyperv_timer.c
> @@ -372,7 +372,9 @@ static void resume_hv_clock_tsc(struct clocksource *arg)
>
> static int hv_cs_enable(struct clocksource *cs)
> {
> - hv_enable_vdso_clocksource();
> +#ifdef VDSO_CLOCKMODE_HVCLOCK
> + vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK);
> +#endif
> return 0;
> }
>
> @@ -385,6 +387,11 @@ static int hv_cs_enable(struct clocksource *cs)
> .suspend= suspend_hv_clock_tsc,
> .resume = resume_hv_clock_tsc,
> .enable = hv_cs_enable,
> +#ifdef VDSO_CLOCKMODE_HVCLOCK
> + .vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK,
> +#else
> + .vdso_clock_mode = VDSO_CLOCKMODE_NONE,
> +#endif
> };
>
> static u64 notrace read_hv_clock_msr(void)
> @@ -439,7 +446,6 @@ static bool __init hv_init_tsc_clocksource(void)
> tsc_msr = tsc_msr | 0x1 | (u64)phys_addr;
> hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr);
>
> - hv_set_clocksource_vdso(hyperv_cs_tsc);
> clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
>
> hv_sched_clock_offset = hv_read_reference_counter();
> --
> 1.8.3.1
>

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