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.
6 * The V3VEE Project is a joint project between Northwestern University
7 * and the University of New Mexico. You can find out more at
10 * Copyright (c) 2011, Jack Lange <jacklange@cs.pitt.edu>
11 * Copyright (c) 2011, The V3VEE Project <http://www.v3vee.org>
12 * All rights reserved.
14 * Author: Jack Lange <jacklangel@cs.pitt.edu>
16 * This is free software. You are permitted to use,
17 * redistribute, and modify it as specified in the file "V3VEE_LICENSE".
21 #include <palacios/vmm_barrier.h>
22 #include <palacios/vmm.h>
23 #include <palacios/vm_guest.h>
25 int v3_init_barrier(struct v3_vm_info * vm_info) {
26 struct v3_barrier * barrier = &(vm_info->barrier);
28 memset(barrier, 0, sizeof(struct v3_barrier));
29 v3_bitmap_init(&(barrier->cpu_map), vm_info->num_cores);
30 v3_lock_init(&(barrier->lock));
35 int v3_deinit_barrier(struct v3_vm_info * vm_info) {
36 struct v3_barrier * barrier = &(vm_info->barrier);
38 v3_bitmap_deinit(&(barrier->cpu_map));
39 v3_lock_deinit(&(barrier->lock));
44 int v3_raise_barrier_nowait(struct v3_vm_info * vm_info, struct guest_info * local_core) {
45 struct v3_barrier * barrier = &(vm_info->barrier);
52 flag = v3_lock_irqsave(barrier->lock);
54 if (barrier->active == 0) {
59 v3_unlock_irqrestore(barrier->lock, flag);
62 /* If we are in a core context and the barrier has already been acquired
63 we'll be safe and let the other barrier proceed. We will still report an error
64 though to allow possible cleanups to occur at the call site.
66 if (local_core != NULL) {
67 v3_wait_at_barrier(local_core);
73 // If we are raising the barrier from a core context
74 // we have to mark ourselves blocked first to avoid deadlock
75 if (local_core != NULL) {
76 local_vcpu = local_core->vcpu_id;
77 v3_bitmap_set(&(barrier->cpu_map), local_vcpu);
81 // send out interrupts to force exits on all cores
82 for (i = 0; i < vm_info->num_cores; i++) {
83 if (vm_info->cores[i].vcpu_id != local_vcpu) {
84 v3_interrupt_cpu(vm_info, vm_info->cores[i].pcpu_id, 0);
91 int v3_wait_for_barrier(struct v3_vm_info * vm_info, struct guest_info * local_core) {
92 struct v3_barrier * barrier = &(vm_info->barrier);
96 // wait for barrier catch on all cores
97 while (all_blocked == 0) {
100 for (i = 0; i < vm_info->num_cores; i++) {
102 // Tricky: If a core is not running then it is safe to ignore it.
103 // Whenever we transition a core to the RUNNING state we MUST immediately wait on the barrier.
104 // TODO: Wrap the state transitions in functions that do this automatically
105 if (vm_info->cores[i].core_run_state != CORE_RUNNING) {
109 if (v3_bitmap_check(&(barrier->cpu_map), i) == 0) {
110 // There is still a core that is not waiting at the barrier
115 if (all_blocked == 1) {
119 v3_yield(local_core);
127 /* Barrier synchronization primitive
128 * -- This call will block until all the guest cores are waiting at a common synchronization point
129 * in a yield loop. The core will block at the sync point until the barrier is lowered.
132 * vm_info -- The VM for which the barrier is being activated
133 * local_core -- The core whose thread this function is being called from, or NULL
134 * if the calling thread is not associated with a VM's core context
137 int v3_raise_barrier(struct v3_vm_info * vm_info, struct guest_info * local_core) {
140 ret = v3_raise_barrier_nowait(vm_info, local_core);
146 return v3_wait_for_barrier(vm_info, local_core);
151 /* Lowers a barrier that has already been raised
152 * guest cores will automatically resume execution
153 * once this has been called
155 * TODO: Need someway to check that the barrier is active
158 int v3_lower_barrier(struct v3_vm_info * vm_info) {
159 struct v3_barrier * barrier = &(vm_info->barrier);
161 // Clear the active flag, so cores won't wait
164 // Clear all the cpu flags, so cores will proceed
165 v3_bitmap_reset(&(barrier->cpu_map));
172 * Syncronization point for guest cores
173 * -- called as part of the main VMM event loop for each core
174 * -- if a barrier has been activated then the core will signal
175 * it has reached the barrier and sit in a yield loop until the
176 * barrier has been lowered
178 int v3_wait_at_barrier(struct guest_info * core) {
179 struct v3_barrier * barrier = &(core->vm_info->barrier);
181 if (barrier->active == 0) {
185 V3_Print("Core %d waiting at barrier\n", core->vcpu_id);
187 /* Barrier has been activated.
188 * Wait here until it's lowered
192 // set cpu bit in barrier bitmap
193 v3_bitmap_set(&(barrier->cpu_map), core->vcpu_id);
194 V3_Print("Core %d bit set as waiting\n", core->vcpu_id);
196 // wait for cpu bit to clear
197 while (v3_bitmap_check(&(barrier->cpu_map), core->vcpu_id)) {