Hi Michael,
On Wed, May 12, 2021 at 10:37:43AM -0700, Michael Kelley wrote:
> Add architecture specific definitions and functions needed
> by the architecture independent Hyper-V clocksource driver.
> Update the Hyper-V clocksource driver to be initialized
> on ARM64.
Previously we've said that for a clocksource we must use the architected
counter, since that's necessary for things like the VDSO to work
correctly and efficiently.
Given that, I'm a bit confused that we're registering a per-cpu
clocksource that is in part based on the architected counter. Likewise,
I don't entirely follow why it's necessary to PV the clock_event_device.
Are the architected counter and timer reliable without this PV
infrastructure? Why do we need to PV either of those?
Thanks,
Mark.
>
> Signed-off-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
> Reviewed-by: Sunil Muthuswamy <sunilmut@xxxxxxxxxxxxx>
> ---
> arch/arm64/include/asm/mshyperv.h | 12 ++++++++++++
> drivers/clocksource/hyperv_timer.c | 14 ++++++++++++++
> 2 files changed, 26 insertions(+)
>
> diff --git a/arch/arm64/include/asm/mshyperv.h b/arch/arm64/include/asm/mshyperv.h
> index c448704..b17299c 100644
> --- a/arch/arm64/include/asm/mshyperv.h
> +++ b/arch/arm64/include/asm/mshyperv.h
> @@ -21,6 +21,7 @@
> #include <linux/types.h>
> #include <linux/arm-smccc.h>
> #include <asm/hyperv-tlfs.h>
> +#include <clocksource/arm_arch_timer.h>
>
> /*
> * Declare calls to get and set Hyper-V VP register values on ARM64, which
> @@ -41,6 +42,17 @@ static inline u64 hv_get_register(unsigned int reg)
> return hv_get_vpreg(reg);
> }
>
> +/* Define the interrupt ID used by STIMER0 Direct Mode interrupts. This
> + * value can't come from ACPI tables because it is needed before the
> + * Linux ACPI subsystem is initialized.
> + */
> +#define HYPERV_STIMER0_VECTOR 31
> +
> +static inline u64 hv_get_raw_timer(void)
> +{
> + return arch_timer_read_counter();
> +}
> +
> /* SMCCC hypercall parameters */
> #define HV_SMCCC_FUNC_NUMBER 1
> #define HV_FUNC_ID ARM_SMCCC_CALL_VAL( \
> diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c
> index 977fd05..270ad9c 100644
> --- a/drivers/clocksource/hyperv_timer.c
> +++ b/drivers/clocksource/hyperv_timer.c
> @@ -569,3 +569,17 @@ void __init hv_init_clocksource(void)
> hv_setup_sched_clock(read_hv_sched_clock_msr);
> }
> EXPORT_SYMBOL_GPL(hv_init_clocksource);
> +
> +/* Initialize everything on ARM64 */
> +static int __init hyperv_timer_init(struct acpi_table_header *table)
> +{
> + if (!hv_is_hyperv_initialized())
> + return -EINVAL;
> +
> + hv_init_clocksource();
> + if (hv_stimer_alloc(true))
> + return -EINVAL;
> +
> + return 0;
> +}
> +TIMER_ACPI_DECLARE(hyperv, ACPI_SIG_GTDT, hyperv_timer_init);
> --
> 1.8.3.1
>
