1 // SPDX-License-Identifier: GPL-2.0
5  * provided by the Hyper-V hypervisor to guest VMs, as described
6  * in the Hyper-V Top Level Functional Spec (TLFS). This driver
26 #include <asm/hyperv-tlfs.h>
35  * mechanism is used when running on older versions of Hyper-V
36  * that don't support Direct Mode. While Hyper-V provides
40  * message, stimer interrupts can be enabled earlier in the
43  * However, for legacy versions of Hyper-V when Direct Mode
50 static int stimer0_irq = -1;
63 	ce->event_handler(ce);  in hv_stimer0_isr()
69  * per-cpu interrupts, which also implies Direct Mode.
127  * hv_stimer_init - Per-cpu initialization of the clockevent
137 	ce->name = "Hyper-V clockevent";  in hv_stimer_init()
138 	ce->features = CLOCK_EVT_FEAT_ONESHOT;  in hv_stimer_init()
139 	ce->cpumask = cpumask_of(cpu);  in hv_stimer_init()
140 	ce->rating = 1000;  in hv_stimer_init()
141 	ce->set_state_shutdown = hv_ce_shutdown;  in hv_stimer_init()
142 	ce->set_state_oneshot = hv_ce_set_oneshot;  in hv_stimer_init()
143 	ce->set_next_event = hv_ce_set_next_event;  in hv_stimer_init()
153  * hv_stimer_cleanup - Per-cpu cleanup of the clockevent
163 	 * In the legacy case where Direct Mode is not enabled  in hv_stimer_cleanup()
165 	 * relatively early in the CPU offlining process. We  in hv_stimer_cleanup()
166 	 * must unbind the stimer-based clockevent device so  in hv_stimer_cleanup()
168 	 * are no longer needed in the offlining process. Note  in hv_stimer_cleanup()
174 	 * there are no other clockevent devices to fallback to.  in hv_stimer_cleanup()
189  * they don't support per-cpu IRQs (such as x86/x64).
199 /* Called only on architectures with per-cpu IRQs (i.e., not x86/x64) */
207 		pr_err("Can't register Hyper-V stimer0 GSI. Error %d", ret);  in hv_setup_stimer0_irq()
213 		"Hyper-V stimer0", &stimer0_evt);  in hv_setup_stimer0_irq()
215 		pr_err("Can't request Hyper-V stimer0 IRQ %d. Error %d",  in hv_setup_stimer0_irq()
218 		stimer0_irq = -1;  in hv_setup_stimer0_irq()
225 	if (stimer0_irq == -1) {  in hv_remove_stimer0_irq()
230 		stimer0_irq = -1;  in hv_remove_stimer0_irq()
234 /* hv_stimer_alloc - Global initialization of the clockevent and stimer0 */
241 	 * Hyper-V on x86.  In that case, return as error as Linux will use a  in hv_stimer_alloc()
245 		return -EINVAL;  in hv_stimer_alloc()
249 		return -ENOMEM;  in hv_stimer_alloc()
270 	 * Since we are in Direct Mode, stimer initialization  in hv_stimer_alloc()
271 	 * can be done now with a CPUHP value in the same range  in hv_stimer_alloc()
291  * hv_stimer_legacy_init -- Called from the VMbus driver to handle
293  * must be initialized late in the CPU onlining process.
304 	 * not ideal, but the value passed in is always the same and  in hv_stimer_legacy_init()
306 	 * clocksource driver just to set the sint in the legacy case.  in hv_stimer_legacy_init()
314  * hv_stimer_legacy_cleanup -- Called from the VMbus driver to
316  * stimer must be cleaned up early in the CPU offlining
349 		stimer0_irq = -1;  in hv_stimer_global_cleanup()
358  * Code and definitions for the Hyper-V clocksources.  Two
359  * clocksources are defined: one that reads the Hyper-V defined MSR, and
360  * the other that uses the TSC reference page feature as defined in the
362  * Hyper-V and 32-bit x86.  The TSC reference page version is preferred.
393 	return (read_hv_clock_tsc() - hv_sched_clock_offset) *  in read_hv_sched_clock_tsc()
413 	/* Re-enable the TSC page */  in resume_hv_clock_tsc()
434 	.suspend= suspend_hv_clock_tsc,
447 	 * Read the partition counter to get the current tick count. This count  in read_hv_clock_msr()
448 	 * is set to 0 when the partition is created and is incremented in  in read_hv_clock_msr()
461 	return (read_hv_clock_msr() - hv_sched_clock_offset) *  in read_hv_sched_clock_msr()
482 	 * The Hyper-V sched clock read function returns nanoseconds, not  in hv_setup_sched_clock()
483 	 * the normal 100ns units of the Hyper-V synthetic clock.  in hv_setup_sched_clock()
509 	 * If Hyper-V offers TSC_INVARIANT, then the virtualized TSC correctly  in hv_init_tsc_clocksource()
512 	 * Hyper-V Reference TSC rating, causing the generic TSC to be used.  in hv_init_tsc_clocksource()
513 	 * TSC_INVARIANT is not offered on ARM64, so the Hyper-V Reference  in hv_init_tsc_clocksource()
515 	 * While the Hyper-V MSR clocksource won't be used since the  in hv_init_tsc_clocksource()
528 	 * The Hyper-V TLFS specifies to preserve the value of reserved  in hv_init_tsc_clocksource()
529 	 * bits in registers. So read the existing value, preserve the  in hv_init_tsc_clocksource()
530 	 * low order 12 bits, and add in the guest physical address  in hv_init_tsc_clocksource()
553 	 * Hyper-V on x86.  In that case we won't have a Hyper-V  in hv_init_clocksource()