osfmk/kern/hv_support.c

   1 /*
   2  * Copyright (c) 2013 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28
  29 #include <kern/locks.h>
  30 #include <kern/task.h>
  31 #include <kern/thread.h>
  32 #include <libkern/OSAtomic.h>
  33 #include <vm/vm_pageout.h>
  34
  35 #if defined(__x86_64__) && CONFIG_VMX
  36 #include <i386/vmx/vmx_cpu.h>
  37 #endif
  38
  39 #include <kern/hv_support.h>
  40
  41 int hv_support_available = 0;
  42
  43 /* callbacks for tasks/threads with associated hv objects */
  44 hv_callbacks_t hv_callbacks = {
  45         .dispatch = NULL,               /* thread is being dispatched for execution */
  46         .preempt = NULL,                /* thread is being preempted */
  47         .thread_destroy = NULL, /* thread is being destroyed */
  48         .task_destroy = NULL,   /* task is being destroyed */
  49         .volatile_state = NULL, /* thread state is becoming volatile */
  50         .memory_pressure = NULL /* memory pressure notification */
  51 };
  52
  53 /* trap tables for hv_*_trap syscalls */
  54 static hv_trap_table_t hv_trap_table[] = {
  55         [HV_TASK_TRAP] = {
  56                 .traps = NULL,
  57                 .trap_count = 0
  58         },
  59         [HV_THREAD_TRAP] = {
  60                 .traps = NULL,
  61                 .trap_count = 0
  62         }
  63 };
  64
  65 static int hv_callbacks_enabled = 0;
  66 static int hv_mp_notify_enabled = 0;
  67 static int hv_mp_notify_destroy = 0;
  68 static lck_grp_t *hv_support_lck_grp = NULL;
  69 static lck_mtx_t *hv_support_lck_mtx = NULL;
  70 static thread_t hv_mp_notify_thread = THREAD_NULL;
  71 static void hv_mp_notify(void);
  72
  73 /* hv_support boot initialization */
  74 void
  75 hv_support_init(void) {
  76 #if defined(__x86_64__) && CONFIG_VMX
  77         hv_support_available = vmx_hv_support();
  78 #endif
  79
  80         hv_support_lck_grp = lck_grp_alloc_init("hv_support", LCK_GRP_ATTR_NULL);
  81         assert(hv_support_lck_grp);
  82
  83         hv_support_lck_mtx = lck_mtx_alloc_init(hv_support_lck_grp, LCK_ATTR_NULL);
  84         assert(hv_support_lck_mtx);
  85 }
  86
  87 /* returns true if hv_support is available on this machine */
  88 int
  89 hv_get_support(void) {
  90         return hv_support_available;
  91 }
  92
  93 /* associate an hv object with the current task */
  94 void
  95 hv_set_task_target(void *target) {
  96         current_task()->hv_task_target = target;
  97 }
  98
  99 /* associate an hv object with the current thread */
 100 void
 101 hv_set_thread_target(void *target) {
 102         current_thread()->hv_thread_target = target;
 103 }
 104
 105 /* get hv object associated with the current task */
 106 void*
 107 hv_get_task_target(void) {
 108         return current_task()->hv_task_target;
 109 }
 110
 111 /* get hv object associated with the current thread */
 112 void*
 113 hv_get_thread_target(void) {
 114         return current_thread()->hv_thread_target;
 115 }
 116
 117 /* test if a given thread state may be volatile between dispatch
 118    and preemption */
 119 int
 120 hv_get_volatile_state(hv_volatile_state_t state) {
 121         int is_volatile = 0;
 122
 123 #if (defined(__x86_64__))
 124         if (state == HV_DEBUG_STATE) {
 125                 is_volatile = (current_thread()->machine.ids != NULL);
 126         }
 127 #endif
 128
 129         return is_volatile;
 130 }
 131
 132 /* memory pressure monitor thread */
 133 static void
 134 hv_mp_notify(void) {
 135         while (1) {
 136                 mach_vm_pressure_monitor(TRUE, 0, NULL, NULL);
 137
 138                 lck_mtx_lock(hv_support_lck_mtx);
 139                 if (hv_mp_notify_destroy == 1) {
 140                         hv_mp_notify_destroy = 0;
 141                         hv_mp_notify_enabled = 0;
 142                         lck_mtx_unlock(hv_support_lck_mtx);
 143                         break;
 144                 } else {
 145                         hv_callbacks.memory_pressure(NULL);
 146                 }
 147                 lck_mtx_unlock(hv_support_lck_mtx);
 148         }
 149
 150         thread_deallocate(current_thread());
 151 }
 152
 153 /* subscribe to memory pressure notifications */
 154 kern_return_t
 155 hv_set_mp_notify(void) {
 156         kern_return_t kr;
 157
 158         lck_mtx_lock(hv_support_lck_mtx);
 159         if (hv_callbacks_enabled == 0) {
 160                 lck_mtx_unlock(hv_support_lck_mtx);
 161                 return KERN_FAILURE;
 162         }
 163
 164         if (hv_mp_notify_enabled == 1) {
 165                 hv_mp_notify_destroy = 0;
 166                 lck_mtx_unlock(hv_support_lck_mtx);
 167                 return KERN_SUCCESS;
 168         }
 169
 170         kr = kernel_thread_start((thread_continue_t) &hv_mp_notify, NULL,
 171                 &hv_mp_notify_thread);
 172
 173         if (kr == KERN_SUCCESS) {
 174                 hv_mp_notify_enabled = 1;
 175         }
 176         lck_mtx_unlock(hv_support_lck_mtx);
 177
 178         return kr;
 179 }
 180
 181 /* unsubscribe from memory pressure notifications */
 182 void
 183 hv_release_mp_notify(void) {
 184         lck_mtx_lock(hv_support_lck_mtx);
 185         if (hv_mp_notify_enabled == 1) {
 186                 hv_mp_notify_destroy = 1;
 187         }
 188         lck_mtx_unlock(hv_support_lck_mtx);
 189 }
 190
 191 /* register a list of trap handlers for the hv_*_trap syscalls */
 192 kern_return_t
 193 hv_set_traps(hv_trap_type_t trap_type, const hv_trap_t *traps,
 194         unsigned trap_count)
 195 {
 196         hv_trap_table_t *trap_table = &hv_trap_table[trap_type];
 197         kern_return_t kr = KERN_FAILURE;
 198
 199         lck_mtx_lock(hv_support_lck_mtx);
 200         if (trap_table->trap_count == 0) {
 201                 trap_table->traps = traps;
 202                 OSMemoryBarrier();
 203                 trap_table->trap_count = trap_count;
 204                 kr = KERN_SUCCESS;
 205         }
 206         lck_mtx_unlock(hv_support_lck_mtx);
 207
 208         return kr;
 209 }
 210
 211 /* release hv_*_trap traps */
 212 void
 213 hv_release_traps(hv_trap_type_t trap_type) {
 214         hv_trap_table_t *trap_table = &hv_trap_table[trap_type];
 215
 216         lck_mtx_lock(hv_support_lck_mtx);
 217         trap_table->trap_count = 0;
 218         OSMemoryBarrier();
 219         trap_table->traps = NULL;
 220         lck_mtx_unlock(hv_support_lck_mtx);
 221 }
 222
 223 /* register callbacks for certain task/thread events for tasks/threads with
 224    associated hv objects */
 225 kern_return_t
 226 hv_set_callbacks(hv_callbacks_t callbacks) {
 227         kern_return_t kr = KERN_FAILURE;
 228
 229         lck_mtx_lock(hv_support_lck_mtx);
 230         if (hv_callbacks_enabled == 0) {
 231                 hv_callbacks = callbacks;
 232                 hv_callbacks_enabled = 1;
 233                 kr = KERN_SUCCESS;
 234         }
 235         lck_mtx_unlock(hv_support_lck_mtx);
 236
 237         return kr;
 238 }
 239
 240 /* release callbacks for task/thread events */
 241 void
 242 hv_release_callbacks(void) {
 243         lck_mtx_lock(hv_support_lck_mtx);
 244         hv_callbacks = (hv_callbacks_t) {
 245                 .dispatch = NULL,
 246                 .preempt = NULL,
 247                 .thread_destroy = NULL,
 248                 .task_destroy = NULL,
 249                 .volatile_state = NULL,
 250                 .memory_pressure = NULL
 251         };
 252
 253         hv_callbacks_enabled = 0;
 254         lck_mtx_unlock(hv_support_lck_mtx);
 255 }
 256
 257 /* dispatch hv_task_trap/hv_thread_trap syscalls to trap handlers,
 258    fail for invalid index or absence of trap handlers, trap handler is
 259    responsible for validating targets */
 260 #define HV_TRAP_DISPATCH(type, index, target, argument)\
 261         ((__probable(index < hv_trap_table[type].trap_count)) ? \
 262                 hv_trap_table[type].traps[index](target, argument) \
 263                         : KERN_INVALID_ARGUMENT)
 264
 265 kern_return_t hv_task_trap(uint64_t index, uint64_t arg) {
 266         return HV_TRAP_DISPATCH(HV_TASK_TRAP, index, hv_get_task_target(), arg);
 267 }
 268
 269 kern_return_t hv_thread_trap(uint64_t index, uint64_t arg) {
 270         return HV_TRAP_DISPATCH(HV_THREAD_TRAP, index, hv_get_thread_target(), arg);
 271 }