vm: implement lazy-attach cow-duplication of vm-objects attached to a controller

syscall/dispatch.c

@@ -47,6 +47,12 @@ static const virt_addr_t syscall_table[] = {
 	SYSCALL_TABLE_ENTRY(
 		VM_CONTROLLER_CREATE_OBJECT,
 		vm_controller_create_object),
+	SYSCALL_TABLE_ENTRY(
+		VM_CONTROLLER_PREPARE_ATTACH,
+		vm_controller_prepare_attach),
+	SYSCALL_TABLE_ENTRY(
+		VM_CONTROLLER_FINISH_ATTACH,
+		vm_controller_finish_attach),
 	SYSCALL_TABLE_ENTRY(
 		VM_CONTROLLER_DETACH_OBJECT,
 		vm_controller_detach_object),

syscall/task.c

@@ -506,8 +506,9 @@ kern_status_t sys_task_duplicate(
 	struct task *new_task = task_create(
 		self->t_name,
 		strlen(self->t_name),
-		NULL);
+		child_handle_table);
 	if (!new_task) {
+		handle_table_destroy(child_handle_table);
 		put_current_task(self);
 		return KERN_NO_MEMORY;
 	}

syscall/vm-controller.c

@@ -32,7 +32,7 @@ kern_status_t sys_vm_controller_create(kern_handle_t *out)
 
 kern_status_t sys_vm_controller_recv(
 	kern_handle_t ctrl_handle,
-	equeue_packet_page_request_t *out)
+	equeue_packet_vm_request_t *out)
 {
 	struct task *self = get_current_task();
 
@@ -209,6 +209,116 @@ kern_status_t sys_vm_controller_create_object(
 	return KERN_OK;
 }
 
+kern_status_t sys_vm_controller_prepare_attach(
+	kern_handle_t ctrl_handle,
+	uint64_t req_id,
+	kern_handle_t *out_vmo)
+{
+	struct task *self = get_current_task();
+	if (!out_vmo || !validate_access_w(self, out_vmo, sizeof *out_vmo)) {
+		return KERN_MEMORY_FAULT;
+	}
+
+	kern_status_t status = KERN_OK;
+	unsigned long flags;
+	task_lock_irqsave(self, &flags);
+
+	struct object *ctrl_obj = NULL;
+	handle_flags_t ctrl_flags = 0;
+	status = task_resolve_handle(self, ctrl_handle, &ctrl_obj, &ctrl_flags);
+	if (status != KERN_OK) {
+		task_unlock_irqrestore(self, flags);
+		put_current_task(self);
+		return status;
+	}
+
+	struct handle *out_slot = NULL;
+	kern_handle_t out_handle = KERN_HANDLE_INVALID;
+	status = handle_table_alloc_handle(
+		self->t_handles,
+		KERN_HANDLE_INVALID,
+		&out_slot,
+		&out_handle);
+	if (status != KERN_OK) {
+		object_unref(ctrl_obj);
+		task_unlock_irqrestore(self, flags);
+		put_current_task(self);
+		return status;
+	}
+
+	struct vm_controller *ctrl = vm_controller_cast(ctrl_obj);
+	task_unlock_irqrestore(self, flags);
+
+	if (!ctrl) {
+		object_unref(ctrl_obj);
+		return KERN_INVALID_ARGUMENT;
+	}
+
+	vm_controller_lock_irqsave(ctrl, &flags);
+
+	struct vm_object *vmo = NULL;
+	status = vm_controller_prepare_attach(ctrl, req_id, &vmo);
+	vm_controller_unlock_irqrestore(ctrl, flags);
+
+	object_unref(ctrl_obj);
+	if (status != KERN_OK) {
+		task_lock_irqsave(self, &flags);
+		handle_table_free_handle(self->t_handles, out_handle);
+		task_unlock_irqrestore(self, flags);
+
+		return status;
+	}
+
+	out_slot->h_object = &vmo->vo_base;
+	put_current_task(self);
+
+	*out_vmo = out_handle;
+
+	return KERN_OK;
+}
+
+kern_status_t sys_vm_controller_finish_attach(
+	kern_handle_t ctrl_handle,
+	uint64_t req_id,
+	equeue_key_t new_key)
+{
+	struct task *self = get_current_task();
+
+	kern_status_t status = KERN_OK;
+	unsigned long flags;
+	task_lock_irqsave(self, &flags);
+
+	struct object *ctrl_obj = NULL;
+	handle_flags_t ctrl_flags = 0;
+	status = task_resolve_handle(self, ctrl_handle, &ctrl_obj, &ctrl_flags);
+	if (status != KERN_OK) {
+		task_unlock_irqrestore(self, flags);
+		put_current_task(self);
+		return status;
+	}
+
+	struct vm_controller *ctrl = vm_controller_cast(ctrl_obj);
+	task_unlock_irqrestore(self, flags);
+	put_current_task(self);
+
+	if (!ctrl) {
+		object_unref(ctrl_obj);
+		return KERN_INVALID_ARGUMENT;
+	}
+
+	vm_controller_lock_irqsave(ctrl, &flags);
+
+	status = vm_controller_finish_attach(ctrl, req_id, new_key);
+	vm_controller_unlock_irqrestore(ctrl, flags);
+
+	object_unref(ctrl_obj);
+	if (status != KERN_OK) {
+		return status;
+	}
+
+	return KERN_OK;
+}
+
 kern_status_t sys_vm_controller_detach_object(
 	kern_handle_t ctrl_handle,
 	kern_handle_t vmo_handle)
@@ -315,6 +425,8 @@ kern_status_t sys_vm_controller_supply_pages(
 
 	vm_controller_lock_irqsave(ctrl, &flags);
 	vm_object_lock_pair(src, dst);
+	equeue_key_t requester_key = dst->vo_key;
+
 	status = vm_controller_supply_pages(
 		ctrl,
 		dst,
@@ -323,6 +435,12 @@ kern_status_t sys_vm_controller_supply_pages(
 		src_offset,
 		count);
 	vm_object_unlock_pair(src, dst);
+	vm_controller_fulfill_requests(
+		ctrl,
+		requester_key,
+		dst_offset,
+		count,
+		status);
 	vm_controller_unlock_irqrestore(ctrl, flags);
 
 	object_unref(ctrl_obj);