Re: [PATCH v10 3/7] arm64: hyperv: Add Hyper-V clocksource/clockevent support
From: Mark Rutland <mark.rutland@arm.com>
Date: 2021-05-14 12:37:20
Also in:
linux-arm-kernel, linux-efi, lkml
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.
quoted hunk ↗ jump to hunk
Signed-off-by: Michael Kelley <redacted> Reviewed-by: Sunil Muthuswamy <redacted> --- 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