// SPDX-License-Identifier: GPL-2.0 /* * Clocksource driver for the synthetic counter and timers * provided by the Hyper-V hypervisor to guest VMs, as described * in the Hyper-V Top Level Functional Spec (TLFS). This driver * is instruction set architecture independent. * * Copyright (C) 2019, Microsoft, Inc. * * Author:  Michael Kelley <mikelley@microsoft.com> */ #include <linux/percpu.h>#include <linux/cpumask.h>#include <linux/clockchips.h>#include <linux/clocksource.h>#include <linux/sched_clock.h>#include <linux/mm.h>#include <linux/cpuhotplug.h>#include <linux/interrupt.h>#include <linux/irq.h>#include <linux/acpi.h>#include <linux/hyperv.h>#include <clocksource/hyperv_timer.h>#include <asm/hyperv-tlfs.h>#include <asm/mshyperv.h> static struct clock_event_device __percpu *hv_clock_event;static u64 hv_sched_clock_offset __ro_after_init; /* * If false, we're using the old mechanism for stimer0 interrupts * where it sends a VMbus message when it expires. The old * mechanism is used when running on older versions of Hyper-V * that don't support Direct Mode. While Hyper-V provides * four stimer's per CPU, Linux uses only stimer0. * * Because Direct Mode does not require processing a VMbus * message, stimer interrupts can be enabled earlier in the * process of booting a CPU, and consistent with when timer * interrupts are enabled for other clocksource drivers. * However, for legacy versions of Hyper-V when Direct Mode * is not enabled, setting up stimer interrupts must be * delayed until VMbus is initialized and can process the * interrupt message. */static bool direct_mode_enabled; static int stimer0_irq = -1;static int stimer0_message_sint;static DEFINE_PER_CPU(long, stimer0_evt); /* * Common code for stimer0 interrupts coming via Direct Mode or * as a VMbus message. */void hv_stimer0_isr(void){	struct clock_event_device *ce; 	ce = this_cpu_ptr(hv_clock_event);	ce->event_handler(ce);}EXPORT_SYMBOL_GPL(hv_stimer0_isr); /* * stimer0 interrupt handler for architectures that support * per-cpu interrupts, which also implies Direct Mode. */static irqreturn_t hv_stimer0_percpu_isr(int irq, void *dev_id){	hv_stimer0_isr();	return IRQ_HANDLED;} static int hv_ce_set_next_event(unsigned long delta,				struct clock_event_device *evt){	u64 current_tick; 	current_tick = hv_read_reference_counter();	current_tick += delta;	hv_set_register(HV_REGISTER_STIMER0_COUNT, current_tick);	return 0;} static int hv_ce_shutdown(struct clock_event_device *evt){	hv_set_register(HV_REGISTER_STIMER0_COUNT, 0);	hv_set_register(HV_REGISTER_STIMER0_CONFIG, 0);	if (direct_mode_enabled && stimer0_irq >= 0)		disable_percpu_irq(stimer0_irq); 	return 0;} static int hv_ce_set_oneshot(struct clock_event_device *evt){	union hv_stimer_config timer_cfg; 	timer_cfg.as_uint64 = 0;	timer_cfg.enable = 1;	timer_cfg.auto_enable = 1;	if (direct_mode_enabled) {		/*		 * When it expires, the timer will directly interrupt		 * on the specified hardware vector/IRQ.		 */		timer_cfg.direct_mode = 1;		timer_cfg.apic_vector = HYPERV_STIMER0_VECTOR;		if (stimer0_irq >= 0)			enable_percpu_irq(stimer0_irq, IRQ_TYPE_NONE);	} else {		/*		 * When it expires, the timer will generate a VMbus message,		 * to be handled by the normal VMbus interrupt handler.		 */		timer_cfg.direct_mode = 0;		timer_cfg.sintx = stimer0_message_sint;	}	hv_set_register(HV_REGISTER_STIMER0_CONFIG, timer_cfg.as_uint64);	return 0;} /* * hv_stimer_init - Per-cpu initialization of the clockevent */static int hv_stimer_init(unsigned int cpu){	struct clock_event_device *ce; 	if (!hv_clock_event)		return 0; 	ce = per_cpu_ptr(hv_clock_event, cpu);	ce->name = "Hyper-V clockevent";	ce->features = CLOCK_EVT_FEAT_ONESHOT;	ce->cpumask = cpumask_of(cpu);	ce->rating = 1000;	ce->set_state_shutdown = hv_ce_shutdown;	ce->set_state_oneshot = hv_ce_set_oneshot;	ce->set_next_event = hv_ce_set_next_event; 	clockevents_config_and_register(ce,					HV_CLOCK_HZ,					HV_MIN_DELTA_TICKS,					HV_MAX_MAX_DELTA_TICKS);	return 0;} /* * hv_stimer_cleanup - Per-cpu cleanup of the clockevent */int hv_stimer_cleanup(unsigned int cpu){	struct clock_event_device *ce; 	if (!hv_clock_event)		return 0; 	/*	 * In the legacy case where Direct Mode is not enabled	 * (which can only be on x86/64), stimer cleanup happens	 * relatively early in the CPU offlining process. We	 * must unbind the stimer-based clockevent device so	 * that the LAPIC timer can take over until clockevents	 * are no longer needed in the offlining process. Note	 * that clockevents_unbind_device() eventually calls	 * hv_ce_shutdown().	 *	 * The unbind should not be done when Direct Mode is	 * enabled because we may be on an architecture where	 * there are no other clockevent devices to fallback to.	 */	ce = per_cpu_ptr(hv_clock_event, cpu);	if (direct_mode_enabled)		hv_ce_shutdown(ce);	else		clockevents_unbind_device(ce, cpu); 	return 0;}EXPORT_SYMBOL_GPL(hv_stimer_cleanup); /* * These placeholders are overridden by arch specific code on * architectures that need special setup of the stimer0 IRQ because * they don't support per-cpu IRQs (such as x86/x64). */void __weak hv_setup_stimer0_handler(void (*handler)(void)){}; void __weak hv_remove_stimer0_handler(void){}; /* Called only on architectures with per-cpu IRQs (i.e., not x86/x64) */static int hv_setup_stimer0_irq(void){	int ret; 	ret = acpi_register_gsi(NULL, HYPERV_STIMER0_VECTOR,			ACPI_EDGE_SENSITIVE, ACPI_ACTIVE_HIGH);	if (ret < 0) {		pr_err("Can't register Hyper-V stimer0 GSI. Error %d", ret);		return ret;	}	stimer0_irq = ret; 	ret = request_percpu_irq(stimer0_irq, hv_stimer0_percpu_isr,		"Hyper-V stimer0", &stimer0_evt);	if (ret) {		pr_err("Can't request Hyper-V stimer0 IRQ %d. Error %d",			stimer0_irq, ret);		acpi_unregister_gsi(stimer0_irq);		stimer0_irq = -1;	}	return ret;} static void hv_remove_stimer0_irq(void){	if (stimer0_irq == -1) {		hv_remove_stimer0_handler();	} else {		free_percpu_irq(stimer0_irq, &stimer0_evt);		acpi_unregister_gsi(stimer0_irq);		stimer0_irq = -1;	}} /* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */int hv_stimer_alloc(bool have_percpu_irqs){	int ret; 	/*	 * Synthetic timers are always available except on old versions of	 * Hyper-V on x86.  In that case, return as error as Linux will use a	 * clockevent based on emulated LAPIC timer hardware.	 */	if (!(ms_hyperv.features & HV_MSR_SYNTIMER_AVAILABLE))		return -EINVAL; 	hv_clock_event = alloc_percpu(struct clock_event_device);	if (!hv_clock_event)		return -ENOMEM; 	direct_mode_enabled = ms_hyperv.misc_features &			HV_STIMER_DIRECT_MODE_AVAILABLE; 	/*	 * If Direct Mode isn't enabled, the remainder of the initialization	 * is done later by hv_stimer_legacy_init()	 */	if (!direct_mode_enabled)		return 0; 	if (have_percpu_irqs) {		ret = hv_setup_stimer0_irq();		if (ret)			goto free_clock_event;	} else {		hv_setup_stimer0_handler(hv_stimer0_isr);	} 	/*	 * Since we are in Direct Mode, stimer initialization	 * can be done now with a CPUHP value in the same range	 * as other clockevent devices.	 */	ret = cpuhp_setup_state(CPUHP_AP_HYPERV_TIMER_STARTING,			"clockevents/hyperv/stimer:starting",			hv_stimer_init, hv_stimer_cleanup);	if (ret < 0) {		hv_remove_stimer0_irq();		goto free_clock_event;	}	return ret; free_clock_event:	free_percpu(hv_clock_event);	hv_clock_event = NULL;	return ret;}EXPORT_SYMBOL_GPL(hv_stimer_alloc); /* * hv_stimer_legacy_init -- Called from the VMbus driver to handle * the case when Direct Mode is not enabled, and the stimer * must be initialized late in the CPU onlining process. * */void hv_stimer_legacy_init(unsigned int cpu, int sint){	if (direct_mode_enabled)		return; 	/*	 * This function gets called by each vCPU, so setting the	 * global stimer_message_sint value each time is conceptually	 * not ideal, but the value passed in is always the same and	 * it avoids introducing yet another interface into this	 * clocksource driver just to set the sint in the legacy case.	 */	stimer0_message_sint = sint;	(void)hv_stimer_init(cpu);}EXPORT_SYMBOL_GPL(hv_stimer_legacy_init); /* * hv_stimer_legacy_cleanup -- Called from the VMbus driver to * handle the case when Direct Mode is not enabled, and the * stimer must be cleaned up early in the CPU offlining * process. */void hv_stimer_legacy_cleanup(unsigned int cpu){	if (direct_mode_enabled)		return;	(void)hv_stimer_cleanup(cpu);}EXPORT_SYMBOL_GPL(hv_stimer_legacy_cleanup); /* * Do a global cleanup of clockevents for the cases of kexec and * vmbus exit */void hv_stimer_global_cleanup(void){	int	cpu; 	/*	 * hv_stime_legacy_cleanup() will stop the stimer if Direct	 * Mode is not enabled, and fallback to the LAPIC timer.	 */	for_each_present_cpu(cpu) {		hv_stimer_legacy_cleanup(cpu);	} 	if (!hv_clock_event)		return; 	if (direct_mode_enabled) {		cpuhp_remove_state(CPUHP_AP_HYPERV_TIMER_STARTING);		hv_remove_stimer0_irq();		stimer0_irq = -1;	}	free_percpu(hv_clock_event);	hv_clock_event = NULL; }EXPORT_SYMBOL_GPL(hv_stimer_global_cleanup); /* * Code and definitions for the Hyper-V clocksources.  Two * clocksources are defined: one that reads the Hyper-V defined MSR, and * the other that uses the TSC reference page feature as defined in the * TLFS.  The MSR version is for compatibility with old versions of * Hyper-V and 32-bit x86.  The TSC reference page version is preferred. */ static union {	struct ms_hyperv_tsc_page page;	u8 reserved[PAGE_SIZE];} tsc_pg __aligned(PAGE_SIZE); static struct ms_hyperv_tsc_page *tsc_page = &tsc_pg.page;static unsigned long tsc_pfn; unsigned long hv_get_tsc_pfn(void){	return tsc_pfn;}EXPORT_SYMBOL_GPL(hv_get_tsc_pfn); struct ms_hyperv_tsc_page *hv_get_tsc_page(void){	return tsc_page;}EXPORT_SYMBOL_GPL(hv_get_tsc_page); static u64 notrace read_hv_clock_tsc(void){	u64 current_tick = hv_read_tsc_page(hv_get_tsc_page()); 	if (current_tick == U64_MAX)		current_tick = hv_get_register(HV_REGISTER_TIME_REF_COUNT); 	return current_tick;} static u64 notrace read_hv_clock_tsc_cs(struct clocksource *arg){	return read_hv_clock_tsc();} static u64 notrace read_hv_sched_clock_tsc(void){	return (read_hv_clock_tsc() - hv_sched_clock_offset) *		(NSEC_PER_SEC / HV_CLOCK_HZ);} static void suspend_hv_clock_tsc(struct clocksource *arg){	union hv_reference_tsc_msr tsc_msr; 	/* Disable the TSC page */	tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);	tsc_msr.enable = 0;	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);}  static void resume_hv_clock_tsc(struct clocksource *arg){	union hv_reference_tsc_msr tsc_msr; 	/* Re-enable the TSC page */	tsc_msr.as_uint64 = hv_get_register(HV_REGISTER_REFERENCE_TSC);	tsc_msr.enable = 1;	tsc_msr.pfn = tsc_pfn;	hv_set_register(HV_REGISTER_REFERENCE_TSC, tsc_msr.as_uint64);} #ifdef HAVE_VDSO_CLOCKMODE_HVCLOCKstatic int hv_cs_enable(struct clocksource *cs){	vclocks_set_used(VDSO_CLOCKMODE_HVCLOCK);	return 0;}#endif static struct clocksource hyperv_cs_tsc = {	.name	= "hyperv_clocksource_tsc_page",	.rating	= 500,	.read	= read_hv_clock_tsc_cs,	.mask	= CLOCKSOURCE_MASK(64),	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,	.suspend= suspend_hv_clock_tsc,	.resume	= resume_hv_clock_tsc,#ifdef HAVE_VDSO_CLOCKMODE_HVCLOCK	.enable = hv_cs_enable,	.vdso_clock_mode = VDSO_CLOCKMODE_HVCLOCK,#else	.vdso_clock_mode = VDSO_CLOCKMODE_NONE,#endif}; static u64 notrace read_hv_clock_msr(void){	/*	 * Read the partition counter to get the current tick count. This count	 * is set to 0 when the partition is created and is incremented in	 * 100 nanosecond units.	 */	return hv_get_register(HV_REGISTER_TIME_REF_COUNT);} static u64 notrace read_hv_clock_msr_cs(struct clocksource *arg){	return read_hv_clock_msr();} static u64 notrace read_hv_sched_clock_msr(void){	return (read_hv_clock_msr() - hv_sched_clock_offset) *		(NSEC_PER_SEC / HV_CLOCK_HZ);} static struct clocksource hyperv_cs_msr = {	.name	= "hyperv_clocksource_msr",	.rating	= 500,	.read	= read_hv_clock_msr_cs,	.mask	= CLOCKSOURCE_MASK(64),	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,}; /* * Reference to pv_ops must be inline so objtool * detection of noinstr violations can work correctly. */#ifdef CONFIG_GENERIC_SCHED_CLOCKstatic __always_inline void hv_setup_sched_clock(void *sched_clock){	/*	 * We're on an architecture with generic sched clock (not x86/x64).	 * The Hyper-V sched clock read function returns nanoseconds, not	 * the normal 100ns units of the Hyper-V synthetic clock.	 */	sched_clock_register(sched_clock, 64, NSEC_PER_SEC);}#elif defined CONFIG_PARAVIRTstatic __always_inline void hv_setup_sched_clock(void *sched_clock){	/* We're on x86/x64 *and* using PV ops */	paravirt_set_sched_clock(sched_clock);}

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