palacios/src/palacios/vmm_lock.c

   1 /*
   2  * This file is part of the Palacios Virtual Machine Monitor developed
   3  * by the V3VEE Project with funding from the United States National
   4  * Science Foundation and the Department of Energy.
   5  *
   6  * The V3VEE Project is a joint project between Northwestern University
   7  * and the University of New Mexico.  You can find out more at
   8  * http://www.v3vee.org
   9  *
  10  * Copyright (c) 2008, Jack Lange <jarusl@cs.northwestern.edu>
  11  * Copyright (c) 2008, The V3VEE Project <http://www.v3vee.org>
  12  * All rights reserved.
  13  *
  14  * Author: Jack Lange <jarusl@cs.northwestern.edu>
  15  *
  16  * This is free software.  You are permitted to use,
  17  * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
  18  */
  19
  20 #include <palacios/vmm.h>
  21 #include <palacios/vmm_lock.h>
  22 #include <palacios/vmm_lowlevel.h>
  23
  24
  25 extern struct v3_os_hooks * os_hooks;
  26
  27
  28 int v3_lock_init(v3_lock_t * lock) {
  29     *lock = (addr_t)(os_hooks->mutex_alloc());
  30
  31     if (!(*lock)) {
  32         return -1;
  33     }
  34
  35     return 0;
  36 }
  37
  38
  39 void v3_lock_deinit(v3_lock_t * lock) {
  40     os_hooks->mutex_free((void *)*lock);
  41     *lock = 0;
  42 }
  43
  44 void v3_lock(v3_lock_t lock) {
  45     os_hooks->mutex_lock((void *)lock, 0);
  46 }
  47
  48 void v3_unlock(v3_lock_t lock) {
  49     os_hooks->mutex_unlock((void *)lock);
  50 }
  51
  52 addr_t v3_lock_irqsave(v3_lock_t lock) {
  53     return (addr_t) (os_hooks->mutex_lock_irqsave((void *)lock, 1));
  54 }
  55
  56
  57 void v3_unlock_irqrestore(v3_lock_t lock, addr_t irq_state) {
  58     os_hooks->mutex_unlock_irqrestore((void *)lock,(void*)irq_state);
  59 }
  60
  61
  62 int v3_rw_lock_init(v3_rw_lock_t *lock)
  63 {
  64     lock->reader_count=0;
  65     return v3_lock_init(&(lock->lock));
  66 }
  67
  68 void v3_rw_lock_deinit(v3_rw_lock_t *lock)
  69 {
  70     v3_lock_deinit(&(lock->lock));
  71     lock->reader_count=0;
  72 }
  73
  74 void v3_read_lock(v3_rw_lock_t *lock)
  75 {
  76     addr_t flags;
  77
  78     flags=v3_lock_irqsave(lock->lock);
  79     lock->reader_count++;
  80     v3_unlock_irqrestore(lock->lock,flags);
  81     // readers can come in after us, writers cannot
  82 }
  83 void v3_read_unlock(v3_rw_lock_t *lock)
  84 {
  85     addr_t flags;
  86
  87     flags=v3_lock_irqsave(lock->lock);
  88     lock->reader_count--;
  89     v3_unlock_irqrestore(lock->lock,flags);
  90     // readers can come in after us, and also writers if reader_count==0
  91 }
  92
  93 void v3_write_lock(v3_rw_lock_t *lock)
  94 {
  95     // a less hideous implementation is possible, of course...
  96     while (1) {
  97         v3_lock(lock->lock);
  98         if (!(lock->reader_count)) {
  99             break;
 100         }
 101         v3_unlock(lock->lock);
 102         V3_Yield();
 103     }
 104     // holding lock now - reader or writer cannot come in after us
 105 }
 106
 107 addr_t v3_write_lock_irqsave(v3_rw_lock_t *lock)
 108 {
 109     addr_t flags;
 110
 111     while (1) {
 112         flags=v3_lock_irqsave(lock->lock);
 113         if (!(lock->reader_count)) {
 114             break;
 115         }
 116         v3_unlock_irqrestore(lock->lock,flags);
 117         V3_Yield();
 118     }
 119     // holding lock now with interrupts off - reader or writer canot come in after us
 120     return flags;
 121 }
 122
 123 void v3_write_unlock(v3_rw_lock_t *lock)
 124 {
 125     // I am already holding this lock
 126     v3_unlock(lock->lock);
 127     // readers/writers can now come in
 128 }
 129
 130 void v3_write_unlock_irqrestore(v3_rw_lock_t *lock, addr_t irq_state)
 131 {
 132     // I am already holding this lock with interrupts off
 133     v3_unlock_irqrestore(lock->lock,irq_state);
 134     // readers/writers can now come in
 135 }