Better support for dynamic changes to page event callbacks

[palacios.git] / palacios / src / palacios / vmm_shadow_paging.c

diff --git a/palacios/src/palacios/vmm_shadow_paging.c b/palacios/src/palacios/vmm_shadow_paging.c
index 10ed641..9650f13 100644 (file)
--- a/palacios/src/palacios/vmm_shadow_paging.c
+++ b/palacios/src/palacios/vmm_shadow_paging.c
@@ -74,19 +74,26 @@ static int shdw_pg_eq_fn(addr_t key1, addr_t key2) {
 
 static int have_callbacks(struct guest_info *core)
 {
+    // lock acquistion unnecessary
+    // caller will acquire the lock before *iterating* through the list
+    // so any race will be resolved then
     return !list_empty(&(core->vm_info->shdw_impl.event_callback_list));
 }
 
 static void dispatch_event(struct guest_info *core, struct v3_shdw_pg_event *event)
 {
     struct event_callback *cb,*temp;
-    
+
+    v3_read_lock(&(core->vm_info->shdw_impl.event_callback_lock));
+
     list_for_each_entry_safe(cb,
                             temp,
                             &(core->vm_info->shdw_impl.event_callback_list),
                             node) {
        cb->callback(core,event,cb->priv_data);
     }
+
+    v3_read_unlock(&(core->vm_info->shdw_impl.event_callback_lock));
 }
 
 
@@ -234,6 +241,7 @@ int v3_init_shdw_impl(struct v3_vm_info * vm) {
     }
 
     INIT_LIST_HEAD(&(impl_state->event_callback_list));
+    v3_rw_lock_init(&(impl_state->event_callback_lock));
    
     impl_state->current_impl = impl;
 
@@ -250,6 +258,7 @@ int v3_init_shdw_impl(struct v3_vm_info * vm) {
 int v3_deinit_shdw_impl(struct v3_vm_info * vm) {
     struct v3_shdw_pg_impl * impl = vm->shdw_impl.current_impl;
     struct event_callback *cb,*temp;
+    addr_t flags;
 
     if (impl == NULL) {
        // Shadow paging not implemented
@@ -261,6 +270,8 @@ int v3_deinit_shdw_impl(struct v3_vm_info * vm) {
        return -1;
     }
 
+    flags=v3_write_lock_irqsave(&(vm->shdw_impl.event_callback_lock));
+
     list_for_each_entry_safe(cb,
                             temp,
                             &(vm->shdw_impl.event_callback_list),
@@ -269,6 +280,10 @@ int v3_deinit_shdw_impl(struct v3_vm_info * vm) {
        V3_Free(cb);
     }
 
+    v3_write_unlock_irqrestore(&(vm->shdw_impl.event_callback_lock),flags);
+
+    v3_rw_lock_deinit(&(vm->shdw_impl.event_callback_lock));
+
     return 0;
 }
 
@@ -478,6 +493,7 @@ int v3_register_shadow_paging_event_callback(struct v3_vm_info *vm,
                                             void *priv_data)
 {
     struct event_callback *ec = V3_Malloc(sizeof(struct event_callback));
+    addr_t flags;
 
     if (!ec) { 
        PrintError(vm, VCORE_NONE, "Unable to allocate for a shadow paging event callback\n");
@@ -487,7 +503,9 @@ int v3_register_shadow_paging_event_callback(struct v3_vm_info *vm,
     ec->callback = callback;
     ec->priv_data = priv_data;
 
+    flags=v3_write_lock_irqsave(&(vm->shdw_impl.event_callback_lock));
     list_add(&(ec->node),&(vm->shdw_impl.event_callback_list));
+    v3_write_unlock_irqrestore(&(vm->shdw_impl.event_callback_lock),flags);
 
     return 0;
 
@@ -500,6 +518,9 @@ int v3_unregister_shadow_paging_event_callback(struct v3_vm_info *vm,
                                               void *priv_data)
 {
     struct event_callback *cb,*temp;
+    addr_t flags;
+
+    flags=v3_write_lock_irqsave(&(vm->shdw_impl.event_callback_lock));
 
     list_for_each_entry_safe(cb,
                             temp,
@@ -507,11 +528,14 @@ int v3_unregister_shadow_paging_event_callback(struct v3_vm_info *vm,
                             node) {
        if ((callback == cb->callback) && (priv_data == cb->priv_data)) { 
            list_del(&(cb->node));
+           v3_write_unlock_irqrestore(&(vm->shdw_impl.event_callback_lock),flags);
            V3_Free(cb);
            return 0;
        }
     }
     
+    v3_write_unlock_irqrestore(&(vm->shdw_impl.event_callback_lock),flags);
+
     PrintError(vm, VCORE_NONE, "No callback found!\n");
     
     return -1;