This is xnu-4903.221.2. See this file in:
/*
 * Copyright (c) 2016 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */

#include <vm/vm_page.h>
#include <vm/pmap.h>
#include <kern/ledger.h>
#include <kern/thread.h>


extern ledger_template_t task_ledger_template;

kern_return_t test_pmap_enter_disconnect(unsigned int num_loops);
kern_return_t test_pmap_iommu_disconnect(void);

#define PMAP_TEST_VA (0xDEAD << PAGE_SHIFT)

typedef struct {
	pmap_t pmap;
	volatile boolean_t stop;
	ppnum_t pn;
} pmap_test_thread_args;	

static pmap_t
pmap_create_wrapper() {
	pmap_t new_pmap = NULL;
	ledger_t ledger;
	assert(task_ledger_template != NULL);
	if ((ledger = ledger_instantiate(task_ledger_template, LEDGER_CREATE_ACTIVE_ENTRIES)) == NULL)
		return NULL;
        new_pmap = pmap_create(ledger, 0, FALSE);
	ledger_dereference(ledger);
	return new_pmap;
}

static void
pmap_disconnect_thread(void *arg, wait_result_t __unused wres) {
	pmap_test_thread_args *args = arg;
	do {
		pmap_disconnect(args->pn);
	} while (!args->stop);
	thread_wakeup((event_t)args);
}

kern_return_t
test_pmap_enter_disconnect(unsigned int num_loops)
{
	kern_return_t kr = KERN_SUCCESS;
	thread_t disconnect_thread;
	pmap_t new_pmap = pmap_create_wrapper();
	if (new_pmap == NULL)
		return KERN_FAILURE;
	vm_page_t m = vm_page_grab();
	if (m == VM_PAGE_NULL) {
		pmap_destroy(new_pmap);
		return KERN_FAILURE;
	}
	ppnum_t phys_page = VM_PAGE_GET_PHYS_PAGE(m);
	pmap_test_thread_args args = {new_pmap, FALSE, phys_page};
	kern_return_t res = kernel_thread_start(pmap_disconnect_thread, &args, &disconnect_thread);
	if (res) {
		pmap_destroy(new_pmap);
		vm_page_lock_queues();
		vm_page_free(m);
		vm_page_unlock_queues();
		return res;
	}
	thread_deallocate(disconnect_thread);

	while (num_loops-- != 0) {
		kr = pmap_enter(new_pmap, PMAP_TEST_VA, phys_page,
		                VM_PROT_READ | VM_PROT_WRITE, VM_PROT_NONE, VM_WIMG_USE_DEFAULT, FALSE);
		assert(kr == KERN_SUCCESS);
	}

	assert_wait((event_t)&args, THREAD_UNINT);
	args.stop = TRUE;
	thread_block(THREAD_CONTINUE_NULL);

	pmap_remove(new_pmap, PMAP_TEST_VA, PMAP_TEST_VA + PAGE_SIZE);
	vm_page_lock_queues();
	vm_page_free(m);
	vm_page_unlock_queues();
	pmap_destroy(new_pmap);
	return KERN_SUCCESS;
}

kern_return_t
test_pmap_iommu_disconnect(void)
{
	return KERN_SUCCESS;
}