1 /* 2 * CDDL HEADER START 3 * 4 * The contents of this file are subject to the terms of the 5 * Common Development and Distribution License (the "License"). 6 * You may not use this file except in compliance with the License. 7 * 8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE 9 * or http://www.opensolaris.org/os/licensing. 10 * See the License for the specific language governing permissions 11 * and limitations under the License. 12 * 13 * When distributing Covered Code, include this CDDL HEADER in each 14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE. 15 * If applicable, add the following below this CDDL HEADER, with the 16 * fields enclosed by brackets "[]" replaced with your own identifying 17 * information: Portions Copyright [yyyy] [name of copyright owner] 18 * 19 * CDDL HEADER END 20 */ 21 22 /* 23 * Copyright 2009 Sun Microsystems, Inc. All rights reserved. 24 * Use is subject to license terms. 25 * Copyright 2016 Joyent, Inc. 26 */ 27 28 #include <sys/types.h> 29 #include <sys/clock.h> 30 #include <sys/panic.h> 31 #include <sys/atomic.h> 32 #include <sys/hypervisor.h> 33 34 #include <sys/archsystm.h> 35 36 /* 37 * On the hypervisor, we have a virtualized system time based upon the 38 * information provided for each VCPU, which is updated every time it is 39 * scheduled onto a real CPU. Thus, none of the traditional code in 40 * i86pc/os/timestamp.c applies, our gethrtime() implementation is run through 41 * the PSM, and there is no scaling step to apply. 42 * 43 * However, the platform does not guarantee monotonicity; thus we have to fake 44 * this up, which is a deeply unpleasant thing to have to do. 45 * 46 * Note that the virtualized interface still relies on the current TSC to 47 * calculate the time in nanoseconds since the VCPU was scheduled, and is thus 48 * subject to all the problems with that. For the most part, the hypervisor is 49 * supposed to deal with them. 50 * 51 * Another wrinkle involves suspend/resume/migration. If we come back and time 52 * is apparently less, we may have resumed on a different machine or on the 53 * same machine after a reboot. In this case we need to maintain an addend to 54 * ensure time continues reasonably. Otherwise we could end up taking a very 55 * long time to expire cyclics in the heap. Thus we have two functions: 56 * 57 * xpv_getsystime() 58 * 59 * The unadulterated system time from the hypervisor. This is only to be 60 * used when programming the hypervisor (setting a timer or calculating 61 * the TOD). 62 * 63 * xpv_gethrtime() 64 * 65 * This is the monotonic hrtime counter to be used by everything else such 66 * as the cyclic subsystem. We should never pass an hrtime directly into 67 * a hypervisor interface, as hrtime_addend may well be non-zero. 68 */ 69 70 int hrtime_fake_mt = 1; 71 static volatile hrtime_t hrtime_last; 72 static hrtime_t hrtime_suspend_time; 73 static hrtime_t hrtime_addend; 74 75 volatile uint32_t hres_lock; 76 hrtime_t hres_last_tick; 77 int64_t hrestime_adj; 78 volatile timestruc_t hrestime; 79 80 /* 81 * These functions are used in DTrace probe context, and must be removed from 82 * fbt consideration. Currently fbt ignores all weak symbols, so this will 83 * achieve that. 84 */ 85 #pragma weak xpv_gethrtime = dtrace_xpv_gethrtime 86 #pragma weak xpv_getsystime = dtrace_xpv_getsystime 87 #pragma weak dtrace_gethrtime = dtrace_xpv_gethrtime 88 #pragma weak tsc_read = dtrace_xpv_gethrtime 89 90 hrtime_t 91 dtrace_xpv_getsystime(void) 92 { 93 vcpu_time_info_t *src; 94 vcpu_time_info_t __vti, *dst = &__vti; 95 uint64_t tsc_delta; 96 uint64_t tsc; 97 hrtime_t result; 98 uint32_t stamp; 99 100 src = &CPU->cpu_m.mcpu_vcpu_info->time; 101 102 /* 103 * Loop until version has not been changed during our update, and a Xen 104 * update is not under way (lowest bit is set). 105 */ 106 do { 107 dst->version = src->version; 108 stamp = CPU->cpu_m.mcpu_istamp; 109 110 membar_consumer(); 111 112 dst->tsc_timestamp = src->tsc_timestamp; 113 dst->system_time = src->system_time; 114 dst->tsc_to_system_mul = src->tsc_to_system_mul; 115 dst->tsc_shift = src->tsc_shift; 116 117 /* 118 * Note that this use of the -actual- TSC register 119 * should probably be the SOLE one in the system on this 120 * paravirtualized platform. 121 */ 122 tsc = __rdtsc_insn(); 123 tsc_delta = tsc - dst->tsc_timestamp; 124 125 membar_consumer(); 126 127 } while (((src->version & 1) | (dst->version ^ src->version)) || 128 CPU->cpu_m.mcpu_istamp != stamp); 129 130 if (dst->tsc_shift >= 0) 131 tsc_delta <<= dst->tsc_shift; 132 else if (dst->tsc_shift < 0) 133 tsc_delta >>= -dst->tsc_shift; 134 135 result = dst->system_time + 136 ((uint64_t)(tsc_delta * (uint64_t)dst->tsc_to_system_mul) >> 32); 137 138 return (result); 139 } 140 141 hrtime_t 142 dtrace_xpv_gethrtime(void) 143 { 144 hrtime_t result = xpv_getsystime() + hrtime_addend; 145 146 if (hrtime_fake_mt) { 147 hrtime_t last; 148 do { 149 last = hrtime_last; 150 if (result < last) 151 result = last + 1; 152 } while (atomic_cas_64((volatile uint64_t *)&hrtime_last, 153 last, result) != last); 154 } 155 156 return (result); 157 } 158 159 void 160 xpv_time_suspend(void) 161 { 162 hrtime_suspend_time = xpv_getsystime(); 163 } 164 165 void 166 xpv_time_resume(void) 167 { 168 hrtime_t delta = xpv_getsystime() - hrtime_suspend_time; 169 170 if (delta < 0) 171 hrtime_addend += -delta; 172 } 173