vmbus_et.c revision 300993 
1/*-
2 * Copyright (c) 2015,2016 Microsoft Corp.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *      notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *      notice, this list of conditions and the following disclaimer in the
12 *      documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/dev/hyperv/vmbus/hv_et.c 300993 2016-05-30 09:35:36Z sephe $");
29
30#include <sys/param.h>
31#include <sys/bus.h>
32#include <sys/kernel.h>
33#include <sys/module.h>
34#include <sys/proc.h>
35#include <sys/systm.h>
36#include <sys/smp.h>
37#include <sys/time.h>
38#include <sys/timeet.h>
39
40#include <dev/hyperv/vmbus/hyperv_reg.h>
41#include <dev/hyperv/vmbus/hyperv_var.h>
42#include <dev/hyperv/vmbus/vmbus_var.h>
43
44#define VMBUS_ET_NAME			"hvet"
45
46#define MSR_HV_STIMER0_CFG_SINT		\
47	((((uint64_t)VMBUS_SINT_TIMER) << MSR_HV_STIMER_CFG_SINT_SHIFT) & \
48	 MSR_HV_STIMER_CFG_SINT_MASK)
49
50/*
51 * Two additionally required features:
52 * - SynIC is needed for interrupt generation.
53 * - Time reference counter is needed to set ABS reference count to
54 *   STIMER0_COUNT.
55 */
56#define CPUID_HV_ET_MASK		(CPUID_HV_MSR_TIME_REFCNT |	\
57					 CPUID_HV_MSR_SYNIC |		\
58					 CPUID_HV_MSR_SYNTIMER)
59
60static struct eventtimer	vmbus_et;
61
62static __inline uint64_t
63hyperv_sbintime2count(sbintime_t time)
64{
65	struct timespec val;
66
67	val = sbttots(time);
68	return (val.tv_sec * HYPERV_TIMER_FREQ) +
69	    (val.tv_nsec / HYPERV_TIMER_NS_FACTOR);
70}
71
72static int
73vmbus_et_start(struct eventtimer *et __unused, sbintime_t first,
74    sbintime_t period __unused)
75{
76	uint64_t current;
77
78	current = rdmsr(MSR_HV_TIME_REF_COUNT);
79	current += hyperv_sbintime2count(first);
80	wrmsr(MSR_HV_STIMER0_COUNT, current);
81
82	return (0);
83}
84
85void
86vmbus_et_intr(struct trapframe *frame)
87{
88	struct trapframe *oldframe;
89	struct thread *td;
90
91	if (vmbus_et.et_active) {
92		td = curthread;
93		td->td_intr_nesting_level++;
94		oldframe = td->td_intr_frame;
95		td->td_intr_frame = frame;
96		vmbus_et.et_event_cb(&vmbus_et, vmbus_et.et_arg);
97		td->td_intr_frame = oldframe;
98		td->td_intr_nesting_level--;
99	}
100}
101
102static void
103vmbus_et_identify(driver_t *driver, device_t parent)
104{
105	if (device_get_unit(parent) != 0 ||
106	    device_find_child(parent, VMBUS_ET_NAME, -1) != NULL ||
107	    (hyperv_features & CPUID_HV_ET_MASK) != CPUID_HV_ET_MASK)
108		return;
109
110	device_add_child(parent, VMBUS_ET_NAME, -1);
111}
112
113static int
114vmbus_et_probe(device_t dev)
115{
116	device_set_desc(dev, "Hyper-V event timer");
117
118	return (BUS_PROBE_NOWILDCARD);
119}
120
121static void
122vmbus_et_config(void *arg __unused)
123{
124	/*
125	 * Make sure that STIMER0 is really disabled before writing
126	 * to STIMER0_CONFIG.
127	 *
128	 * "Writing to the configuration register of a timer that
129	 *  is already enabled may result in undefined behaviour."
130	 */
131	for (;;) {
132		uint64_t val;
133
134		/* Stop counting, and this also implies disabling STIMER0 */
135		wrmsr(MSR_HV_STIMER0_COUNT, 0);
136
137		val = rdmsr(MSR_HV_STIMER0_CONFIG);
138		if ((val & MSR_HV_STIMER_CFG_ENABLE) == 0)
139			break;
140		cpu_spinwait();
141	}
142	wrmsr(MSR_HV_STIMER0_CONFIG,
143	    MSR_HV_STIMER_CFG_AUTOEN | MSR_HV_STIMER0_CFG_SINT);
144}
145
146static int
147vmbus_et_attach(device_t dev)
148{
149	/* TODO: use independent IDT vector */
150
151	vmbus_et.et_name = "Hyper-V";
152	vmbus_et.et_flags = ET_FLAGS_ONESHOT | ET_FLAGS_PERCPU;
153	vmbus_et.et_quality = 1000;
154	vmbus_et.et_frequency = HYPERV_TIMER_FREQ;
155	vmbus_et.et_min_period = (0x00000001ULL << 32) / HYPERV_TIMER_FREQ;
156	vmbus_et.et_max_period = (0xfffffffeULL << 32) / HYPERV_TIMER_FREQ;
157	vmbus_et.et_start = vmbus_et_start;
158
159	/*
160	 * Delay a bit to make sure that MSR_HV_TIME_REF_COUNT will
161	 * not return 0, since writing 0 to STIMER0_COUNT will disable
162	 * STIMER0.
163	 */
164	DELAY(100);
165	smp_rendezvous(NULL, vmbus_et_config, NULL, NULL);
166
167	return (et_register(&vmbus_et));
168}
169
170static int
171vmbus_et_detach(device_t dev)
172{
173	return (et_deregister(&vmbus_et));
174}
175
176static device_method_t vmbus_et_methods[] = {
177	DEVMETHOD(device_identify,	vmbus_et_identify),
178	DEVMETHOD(device_probe,		vmbus_et_probe),
179	DEVMETHOD(device_attach,	vmbus_et_attach),
180	DEVMETHOD(device_detach,	vmbus_et_detach),
181
182	DEVMETHOD_END
183};
184
185static driver_t vmbus_et_driver = {
186	VMBUS_ET_NAME,
187	vmbus_et_methods,
188	0
189};
190
191static devclass_t vmbus_et_devclass;
192DRIVER_MODULE(hv_et, vmbus, vmbus_et_driver, vmbus_et_devclass, NULL, NULL);
193MODULE_VERSION(hv_et, 1);
194