xref: /linux/tools/testing/selftests/kvm/arm64/arch_timer_edge_cases.c (revision 7b609187684db646d4854ada6f7e19a6420b4621)

// SPDX-License-Identifier: GPL-2.0-only
/*
 * arch_timer_edge_cases.c - Tests the aarch64 timer IRQ functionality.
 *
 * The test validates some edge cases related to the arch-timer:
 * - timers above the max TVAL value.
 * - timers in the past
 * - moving counters ahead and behind pending timers.
 * - reprograming timers.
 * - timers fired multiple times.
 * - masking/unmasking using the timer control mask.
 *
 * Copyright (c) 2021, Google LLC.
 */

#define _GNU_SOURCE

#include <pthread.h>
#include <sys/sysinfo.h>

#include "arch_timer.h"
#include "gic.h"
#include "vgic.h"

/* Depends on counter width. */
static u64 CVAL_MAX;
/* tval is a signed 32-bit int. */
static const s32 TVAL_MAX = INT32_MAX;
static const s32 TVAL_MIN = INT32_MIN;

/* After how much time we say there is no IRQ. */
static const u32 TIMEOUT_NO_IRQ_US = 50000;

/* Counter value to use as the starting one for most tests. Set to CVAL_MAX/2 */
static u64 DEF_CNT;

/* Number of runs. */
static const u32 NR_TEST_ITERS_DEF = 5;

/* Default wait test time in ms. */
static const u32 WAIT_TEST_MS = 10;

/* Default "long" wait test time in ms. */
static const u32 LONG_WAIT_TEST_MS = 100;

/* Shared with IRQ handler. */
struct test_vcpu_shared_data {
	atomic_t handled;
	atomic_t spurious;
} shared_data;

struct test_args {
	/* Virtual or physical timer and counter tests. */
	enum arch_timer timer;
	/* Delay used for most timer tests. */
	u64 wait_ms;
	/* Delay used in the test_long_timer_delays test. */
	u64 long_wait_ms;
	/* Number of iterations. */
	int iterations;
	/* Whether to test the physical timer. */
	bool test_physical;
	/* Whether to test the virtual timer. */
	bool test_virtual;
};

struct test_args test_args = {
	.wait_ms = WAIT_TEST_MS,
	.long_wait_ms = LONG_WAIT_TEST_MS,
	.iterations = NR_TEST_ITERS_DEF,
	.test_physical = true,
	.test_virtual = true,
};

static int vtimer_irq, ptimer_irq;

enum sync_cmd {
	SET_COUNTER_VALUE,
	USERSPACE_USLEEP,
	USERSPACE_SCHED_YIELD,
	USERSPACE_MIGRATE_SELF,
	NO_USERSPACE_CMD,
};

typedef void (*sleep_method_t)(enum arch_timer timer, u64 usec);

static void sleep_poll(enum arch_timer timer, u64 usec);
static void sleep_sched_poll(enum arch_timer timer, u64 usec);
static void sleep_in_userspace(enum arch_timer timer, u64 usec);
static void sleep_migrate(enum arch_timer timer, u64 usec);

sleep_method_t sleep_method[] = {
	sleep_poll,
	sleep_sched_poll,
	sleep_migrate,
	sleep_in_userspace,
};

typedef void (*irq_wait_method_t)(void);

static void wait_for_non_spurious_irq(void);
static void wait_poll_for_irq(void);
static void wait_sched_poll_for_irq(void);
static void wait_migrate_poll_for_irq(void);

irq_wait_method_t irq_wait_method[] = {
	wait_for_non_spurious_irq,
	wait_poll_for_irq,
	wait_sched_poll_for_irq,
	wait_migrate_poll_for_irq,
};

enum timer_view {
	TIMER_CVAL,
	TIMER_TVAL,
};

static void assert_irqs_handled(u32 n)
{
	int h = atomic_read(&shared_data.handled);

	__GUEST_ASSERT(h == n, "Handled %d IRQS but expected %d", h, n);
}

static void userspace_cmd(u64 cmd)
{
	GUEST_SYNC_ARGS(cmd, 0, 0, 0, 0);
}

static void userspace_migrate_vcpu(void)
{
	userspace_cmd(USERSPACE_MIGRATE_SELF);
}

static void userspace_sleep(u64 usecs)
{
	GUEST_SYNC_ARGS(USERSPACE_USLEEP, usecs, 0, 0, 0);
}

static void set_counter(enum arch_timer timer, u64 counter)
{
	GUEST_SYNC_ARGS(SET_COUNTER_VALUE, counter, timer, 0, 0);
}

static void guest_irq_handler(struct ex_regs *regs)
{
	unsigned int intid = gic_get_and_ack_irq();
	enum arch_timer timer;
	u64 cnt, cval;
	u32 ctl;
	bool timer_condition, istatus;

	if (intid == IAR_SPURIOUS) {
		atomic_inc(&shared_data.spurious);
		goto out;
	}

	if (intid == ptimer_irq)
		timer = PHYSICAL;
	else if (intid == vtimer_irq)
		timer = VIRTUAL;
	else
		goto out;

	ctl = timer_get_ctl(timer);
	cval = timer_get_cval(timer);
	cnt = timer_get_cntct(timer);
	timer_condition = cnt >= cval;
	istatus = (ctl & CTL_ISTATUS) && (ctl & CTL_ENABLE);
	GUEST_ASSERT_EQ(timer_condition, istatus);

	/* Disable and mask the timer. */
	timer_set_ctl(timer, CTL_IMASK);

	atomic_inc(&shared_data.handled);

out:
	gic_set_eoi(intid);
}

static void set_cval_irq(enum arch_timer timer, u64 cval_cycles,
			 u32 ctl)
{
	atomic_set(&shared_data.handled, 0);
	atomic_set(&shared_data.spurious, 0);
	timer_set_cval(timer, cval_cycles);
	timer_set_ctl(timer, ctl);
}

static void set_tval_irq(enum arch_timer timer, u64 tval_cycles,
			 u32 ctl)
{
	atomic_set(&shared_data.handled, 0);
	atomic_set(&shared_data.spurious, 0);
	timer_set_tval(timer, tval_cycles);
	timer_set_ctl(timer, ctl);
}

static void set_xval_irq(enum arch_timer timer, u64 xval, u32 ctl,
			 enum timer_view tv)
{
	switch (tv) {
	case TIMER_CVAL:
		set_cval_irq(timer, xval, ctl);
		break;
	case TIMER_TVAL:
		set_tval_irq(timer, xval, ctl);
		break;
	default:
		GUEST_FAIL("Could not get timer %d", timer);
	}
}

/*
 * Note that this can theoretically hang forever, so we rely on having
 * a timeout mechanism in the "runner", like:
 * tools/testing/selftests/kselftest/runner.sh.
 */
static void wait_for_non_spurious_irq(void)
{
	int h;

	local_irq_disable();

	for (h = atomic_read(&shared_data.handled); h == atomic_read(&shared_data.handled);) {
		wfi();
		local_irq_enable();
		isb(); /* handle IRQ */
		local_irq_disable();
	}
}

/*
 * Wait for an non-spurious IRQ by polling in the guest or in
 * userspace (e.g. userspace_cmd=USERSPACE_SCHED_YIELD).
 *
 * Note that this can theoretically hang forever, so we rely on having
 * a timeout mechanism in the "runner", like:
 * tools/testing/selftests/kselftest/runner.sh.
 */
static void poll_for_non_spurious_irq(enum sync_cmd usp_cmd)
{
	int h;

	local_irq_disable();

	h = atomic_read(&shared_data.handled);

	local_irq_enable();
	while (h == atomic_read(&shared_data.handled)) {
		if (usp_cmd == NO_USERSPACE_CMD)
			cpu_relax();
		else
			userspace_cmd(usp_cmd);
	}
	local_irq_disable();
}

static void wait_poll_for_irq(void)
{
	poll_for_non_spurious_irq(NO_USERSPACE_CMD);
}

static void wait_sched_poll_for_irq(void)
{
	poll_for_non_spurious_irq(USERSPACE_SCHED_YIELD);
}

static void wait_migrate_poll_for_irq(void)
{
	poll_for_non_spurious_irq(USERSPACE_MIGRATE_SELF);
}

/*
 * Sleep for usec microseconds by polling in the guest or in
 * userspace (e.g. userspace_cmd=USERSPACE_SCHEDULE).
 */
static void guest_poll(enum arch_timer test_timer, u64 usec,
		       enum sync_cmd usp_cmd)
{
	u64 cycles = usec_to_cycles(usec);
	/* Whichever timer we are testing with, sleep with the other. */
	enum arch_timer sleep_timer = 1 - test_timer;
	u64 start = timer_get_cntct(sleep_timer);

	while ((timer_get_cntct(sleep_timer) - start) < cycles) {
		if (usp_cmd == NO_USERSPACE_CMD)
			cpu_relax();
		else
			userspace_cmd(usp_cmd);
	}
}

static void sleep_poll(enum arch_timer timer, u64 usec)
{
	guest_poll(timer, usec, NO_USERSPACE_CMD);
}

static void sleep_sched_poll(enum arch_timer timer, u64 usec)
{
	guest_poll(timer, usec, USERSPACE_SCHED_YIELD);
}

static void sleep_migrate(enum arch_timer timer, u64 usec)
{
	guest_poll(timer, usec, USERSPACE_MIGRATE_SELF);
}

static void sleep_in_userspace(enum arch_timer timer, u64 usec)
{
	userspace_sleep(usec);
}

/*
 * Reset the timer state to some nice values like the counter not being close
 * to the edge, and the control register masked and disabled.
 */
static void reset_timer_state(enum arch_timer timer, u64 cnt)
{
	set_counter(timer, cnt);
	timer_set_ctl(timer, CTL_IMASK);
}

static void test_timer_xval(enum arch_timer timer, u64 xval,
			    enum timer_view tv, irq_wait_method_t wm, bool reset_state,
			    u64 reset_cnt)
{
	local_irq_disable();

	if (reset_state)
		reset_timer_state(timer, reset_cnt);

	set_xval_irq(timer, xval, CTL_ENABLE, tv);

	/* This method re-enables IRQs to handle the one we're looking for. */
	wm();

	assert_irqs_handled(1);
	local_irq_enable();
}

/*
 * The test_timer_* functions will program the timer, wait for it, and assert
 * the firing of the correct IRQ.
 *
 * These functions don't have a timeout and return as soon as they receive an
 * IRQ. They can hang (forever), so we rely on having a timeout mechanism in
 * the "runner", like: tools/testing/selftests/kselftest/runner.sh.
 */

static void test_timer_cval(enum arch_timer timer, u64 cval,
			    irq_wait_method_t wm, bool reset_state,
			    u64 reset_cnt)
{
	test_timer_xval(timer, cval, TIMER_CVAL, wm, reset_state, reset_cnt);
}

static void test_timer_tval(enum arch_timer timer, s32 tval,
			    irq_wait_method_t wm, bool reset_state,
			    u64 reset_cnt)
{
	test_timer_xval(timer, (u64)tval, TIMER_TVAL, wm, reset_state,
			reset_cnt);
}

static void test_xval_check_no_irq(enum arch_timer timer, u64 xval,
				   u64 usec, enum timer_view timer_view,
				   sleep_method_t guest_sleep)
{
	local_irq_disable();

	set_xval_irq(timer, xval, CTL_ENABLE | CTL_IMASK, timer_view);
	guest_sleep(timer, usec);

	local_irq_enable();
	isb();

	/* Assume success (no IRQ) after waiting usec microseconds */
	assert_irqs_handled(0);
}

static void test_cval_no_irq(enum arch_timer timer, u64 cval,
			     u64 usec, sleep_method_t wm)
{
	test_xval_check_no_irq(timer, cval, usec, TIMER_CVAL, wm);
}

static void test_tval_no_irq(enum arch_timer timer, s32 tval, u64 usec,
			     sleep_method_t wm)
{
	/* tval will be cast to an s32 in test_xval_check_no_irq */
	test_xval_check_no_irq(timer, (u64)tval, usec, TIMER_TVAL, wm);
}

/* Test masking/unmasking a timer using the timer mask (not the IRQ mask). */
static void test_timer_control_mask_then_unmask(enum arch_timer timer)
{
	reset_timer_state(timer, DEF_CNT);
	set_tval_irq(timer, -1, CTL_ENABLE | CTL_IMASK);

	/* Unmask the timer, and then get an IRQ. */
	local_irq_disable();
	timer_set_ctl(timer, CTL_ENABLE);
	/* This method re-enables IRQs to handle the one we're looking for. */
	wait_for_non_spurious_irq();

	assert_irqs_handled(1);
	local_irq_enable();
}

/* Check that timer control masks actually mask a timer being fired. */
static void test_timer_control_masks(enum arch_timer timer)
{
	reset_timer_state(timer, DEF_CNT);

	/* Local IRQs are not masked at this point. */

	set_tval_irq(timer, -1, CTL_ENABLE | CTL_IMASK);

	/* Assume no IRQ after waiting TIMEOUT_NO_IRQ_US microseconds */
	sleep_poll(timer, TIMEOUT_NO_IRQ_US);

	assert_irqs_handled(0);
	timer_set_ctl(timer, CTL_IMASK);
}

static void test_fire_a_timer_multiple_times(enum arch_timer timer,
					     irq_wait_method_t wm, int num)
{
	int i;

	local_irq_disable();
	reset_timer_state(timer, DEF_CNT);

	set_tval_irq(timer, 0, CTL_ENABLE);

	for (i = 1; i <= num; i++) {
		/* This method re-enables IRQs to handle the one we're looking for. */
		wm();

		/* The IRQ handler masked and disabled the timer.
		 * Enable and unmmask it again.
		 */
		timer_set_ctl(timer, CTL_ENABLE);

		assert_irqs_handled(i);
	}

	local_irq_enable();
}

static void test_timers_fired_multiple_times(enum arch_timer timer)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(irq_wait_method); i++)
		test_fire_a_timer_multiple_times(timer, irq_wait_method[i], 10);
}

/*
 * Set a timer for tval=delta_1_ms then reprogram it to
 * tval=delta_2_ms. Check that we get the timer fired. There is no
 * timeout for the wait: we use the wfi instruction.
 */
static void test_reprogramming_timer(enum arch_timer timer, irq_wait_method_t wm,
				     s32 delta_1_ms, s32 delta_2_ms)
{
	local_irq_disable();
	reset_timer_state(timer, DEF_CNT);

	/* Program the timer to DEF_CNT + delta_1_ms. */
	set_tval_irq(timer, msec_to_cycles(delta_1_ms), CTL_ENABLE);

	/* Reprogram the timer to DEF_CNT + delta_2_ms. */
	timer_set_tval(timer, msec_to_cycles(delta_2_ms));

	/* This method re-enables IRQs to handle the one we're looking for. */
	wm();

	/* The IRQ should arrive at DEF_CNT + delta_2_ms (or after). */
	GUEST_ASSERT(timer_get_cntct(timer) >=
		     DEF_CNT + msec_to_cycles(delta_2_ms));

	local_irq_enable();
	assert_irqs_handled(1);
};

static void test_reprogram_timers(enum arch_timer timer)
{
	int i;
	u64 base_wait = test_args.wait_ms;

	for (i = 0; i < ARRAY_SIZE(irq_wait_method); i++) {
		/*
		 * Ensure reprogramming works whether going from a
		 * longer time to a shorter or vice versa.
		 */
		test_reprogramming_timer(timer, irq_wait_method[i], 2 * base_wait,
					 base_wait);
		test_reprogramming_timer(timer, irq_wait_method[i], base_wait,
					 2 * base_wait);
	}
}

static void test_basic_functionality(enum arch_timer timer)
{
	s32 tval = (s32)msec_to_cycles(test_args.wait_ms);
	u64 cval = DEF_CNT + msec_to_cycles(test_args.wait_ms);
	int i;

	for (i = 0; i < ARRAY_SIZE(irq_wait_method); i++) {
		irq_wait_method_t wm = irq_wait_method[i];

		test_timer_cval(timer, cval, wm, true, DEF_CNT);
		test_timer_tval(timer, tval, wm, true, DEF_CNT);
	}
}

/*
 * This test checks basic timer behavior without actually firing timers, things
 * like: the relationship between cval and tval, tval down-counting.
 */
static void timers_sanity_checks(enum arch_timer timer, bool use_sched)
{
	reset_timer_state(timer, DEF_CNT);

	local_irq_disable();

	/* cval in the past */
	timer_set_cval(timer,
		       timer_get_cntct(timer) -
		       msec_to_cycles(test_args.wait_ms));
	if (use_sched)
		userspace_migrate_vcpu();
	GUEST_ASSERT(timer_get_tval(timer) < 0);

	/* tval in the past */
	timer_set_tval(timer, -1);
	if (use_sched)
		userspace_migrate_vcpu();
	GUEST_ASSERT(timer_get_cval(timer) < timer_get_cntct(timer));

	/* tval larger than TVAL_MAX. This requires programming with
	 * timer_set_cval instead so the value is expressible
	 */
	timer_set_cval(timer,
		       timer_get_cntct(timer) + TVAL_MAX +
		       msec_to_cycles(test_args.wait_ms));
	if (use_sched)
		userspace_migrate_vcpu();
	GUEST_ASSERT(timer_get_tval(timer) <= 0);

	/*
	 * tval larger than 2 * TVAL_MAX.
	 * Twice the TVAL_MAX completely loops around the TVAL.
	 */
	timer_set_cval(timer,
		       timer_get_cntct(timer) + 2ULL * TVAL_MAX +
		       msec_to_cycles(test_args.wait_ms));
	if (use_sched)
		userspace_migrate_vcpu();
	GUEST_ASSERT(timer_get_tval(timer) <=
		       msec_to_cycles(test_args.wait_ms));

	/* negative tval that rollovers from 0. */
	set_counter(timer, msec_to_cycles(1));
	timer_set_tval(timer, -1 * msec_to_cycles(test_args.wait_ms));
	if (use_sched)
		userspace_migrate_vcpu();
	GUEST_ASSERT(timer_get_cval(timer) >= (CVAL_MAX - msec_to_cycles(test_args.wait_ms)));

	/* tval should keep down-counting from 0 to -1. */
	timer_set_tval(timer, 0);
	sleep_poll(timer, 1);
	GUEST_ASSERT(timer_get_tval(timer) < 0);

	local_irq_enable();

	/* Mask and disable any pending timer. */
	timer_set_ctl(timer, CTL_IMASK);
}

static void test_timers_sanity_checks(enum arch_timer timer)
{
	timers_sanity_checks(timer, false);
	/* Check how KVM saves/restores these edge-case values. */
	timers_sanity_checks(timer, true);
}

static void test_set_cnt_after_tval_max(enum arch_timer timer, irq_wait_method_t wm)
{
	local_irq_disable();
	reset_timer_state(timer, DEF_CNT);

	set_cval_irq(timer,
		     (u64)TVAL_MAX +
		     msec_to_cycles(test_args.wait_ms) / 2, CTL_ENABLE);

	set_counter(timer, TVAL_MAX);

	/* This method re-enables IRQs to handle the one we're looking for. */
	wm();

	assert_irqs_handled(1);
	local_irq_enable();
}

/* Test timers set for: cval = now + TVAL_MAX + wait_ms / 2 */
static void test_timers_above_tval_max(enum arch_timer timer)
{
	u64 cval;
	int i;

	/*
	 * Test that the system is not implementing cval in terms of
	 * tval.  If that was the case, setting a cval to "cval = now
	 * + TVAL_MAX + wait_ms" would wrap to "cval = now +
	 * wait_ms", and the timer would fire immediately. Test that it
	 * doesn't.
	 */
	for (i = 0; i < ARRAY_SIZE(sleep_method); i++) {
		reset_timer_state(timer, DEF_CNT);
		cval = timer_get_cntct(timer) + TVAL_MAX +
			msec_to_cycles(test_args.wait_ms);
		test_cval_no_irq(timer, cval,
				 msecs_to_usecs(test_args.wait_ms) +
				 TIMEOUT_NO_IRQ_US, sleep_method[i]);
	}

	for (i = 0; i < ARRAY_SIZE(irq_wait_method); i++) {
		/* Get the IRQ by moving the counter forward. */
		test_set_cnt_after_tval_max(timer, irq_wait_method[i]);
	}
}

/*
 * Template function to be used by the test_move_counter_ahead_* tests.  It
 * sets the counter to cnt_1, the [c|t]val, the counter to cnt_2, and
 * then waits for an IRQ.
 */
static void test_set_cnt_after_xval(enum arch_timer timer, u64 cnt_1,
				    u64 xval, u64 cnt_2,
				    irq_wait_method_t wm, enum timer_view tv)
{
	local_irq_disable();

	set_counter(timer, cnt_1);
	timer_set_ctl(timer, CTL_IMASK);

	set_xval_irq(timer, xval, CTL_ENABLE, tv);
	set_counter(timer, cnt_2);
	/* This method re-enables IRQs to handle the one we're looking for. */
	wm();

	assert_irqs_handled(1);
	local_irq_enable();
}

/*
 * Template function to be used by the test_move_counter_ahead_* tests.  It
 * sets the counter to cnt_1, the [c|t]val, the counter to cnt_2, and
 * then waits for an IRQ.
 */
static void test_set_cnt_after_xval_no_irq(enum arch_timer timer,
					   u64 cnt_1, u64 xval,
					   u64 cnt_2,
					   sleep_method_t guest_sleep,
					   enum timer_view tv)
{
	local_irq_disable();

	set_counter(timer, cnt_1);
	timer_set_ctl(timer, CTL_IMASK);

	set_xval_irq(timer, xval, CTL_ENABLE, tv);
	set_counter(timer, cnt_2);
	guest_sleep(timer, TIMEOUT_NO_IRQ_US);

	local_irq_enable();
	isb();

	/* Assume no IRQ after waiting TIMEOUT_NO_IRQ_US microseconds */
	assert_irqs_handled(0);
	timer_set_ctl(timer, CTL_IMASK);
}

static void test_set_cnt_after_tval(enum arch_timer timer, u64 cnt_1,
				    s32 tval, u64 cnt_2,
				    irq_wait_method_t wm)
{
	test_set_cnt_after_xval(timer, cnt_1, tval, cnt_2, wm, TIMER_TVAL);
}

static void test_set_cnt_after_cval(enum arch_timer timer, u64 cnt_1,
				    u64 cval, u64 cnt_2,
				    irq_wait_method_t wm)
{
	test_set_cnt_after_xval(timer, cnt_1, cval, cnt_2, wm, TIMER_CVAL);
}

static void test_set_cnt_after_tval_no_irq(enum arch_timer timer,
					   u64 cnt_1, s32 tval,
					   u64 cnt_2, sleep_method_t wm)
{
	test_set_cnt_after_xval_no_irq(timer, cnt_1, tval, cnt_2, wm,
				       TIMER_TVAL);
}

static void test_set_cnt_after_cval_no_irq(enum arch_timer timer,
					   u64 cnt_1, u64 cval,
					   u64 cnt_2, sleep_method_t wm)
{
	test_set_cnt_after_xval_no_irq(timer, cnt_1, cval, cnt_2, wm,
				       TIMER_CVAL);
}

/* Set a timer and then move the counter ahead of it. */
static void test_move_counters_ahead_of_timers(enum arch_timer timer)
{
	int i;
	s32 tval;

	for (i = 0; i < ARRAY_SIZE(irq_wait_method); i++) {
		irq_wait_method_t wm = irq_wait_method[i];

		test_set_cnt_after_cval(timer, 0, DEF_CNT, DEF_CNT + 1, wm);
		test_set_cnt_after_cval(timer, CVAL_MAX, 1, 2, wm);

		/* Move counter ahead of negative tval. */
		test_set_cnt_after_tval(timer, 0, -1, DEF_CNT + 1, wm);
		test_set_cnt_after_tval(timer, 0, -1, TVAL_MAX, wm);
		tval = TVAL_MAX;
		test_set_cnt_after_tval(timer, 0, tval, (u64)tval + 1, wm);
	}
}

/*
 * Program a timer, mask it, and then change the tval or counter to cancel it.
 * Unmask it and check that nothing fires.
 */
static void test_move_counters_behind_timers(enum arch_timer timer)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(sleep_method); i++) {
		sleep_method_t sm = sleep_method[i];

		test_set_cnt_after_cval_no_irq(timer, DEF_CNT, DEF_CNT - 1, 0,
					       sm);
		test_set_cnt_after_tval_no_irq(timer, DEF_CNT, -1, 0, sm);
	}
}

static void test_timers_in_the_past(enum arch_timer timer)
{
	s32 tval = -1 * (s32)msec_to_cycles(test_args.wait_ms);
	u64 cval;
	int i;

	for (i = 0; i < ARRAY_SIZE(irq_wait_method); i++) {
		irq_wait_method_t wm = irq_wait_method[i];

		/* set a timer wait_ms the past. */
		cval = DEF_CNT - msec_to_cycles(test_args.wait_ms);
		test_timer_cval(timer, cval, wm, true, DEF_CNT);
		test_timer_tval(timer, tval, wm, true, DEF_CNT);

		/* Set a timer to counter=0 (in the past) */
		test_timer_cval(timer, 0, wm, true, DEF_CNT);

		/* Set a time for tval=0 (now) */
		test_timer_tval(timer, 0, wm, true, DEF_CNT);

		/* Set a timer to as far in the past as possible */
		test_timer_tval(timer, TVAL_MIN, wm, true, DEF_CNT);
	}

	/*
	 * Set the counter to wait_ms, and a tval to -wait_ms. There should be no
	 * IRQ as that tval means cval=CVAL_MAX-wait_ms.
	 */
	for (i = 0; i < ARRAY_SIZE(sleep_method); i++) {
		sleep_method_t sm = sleep_method[i];

		set_counter(timer, msec_to_cycles(test_args.wait_ms));
		test_tval_no_irq(timer, tval, TIMEOUT_NO_IRQ_US, sm);
	}
}

static void test_long_timer_delays(enum arch_timer timer)
{
	s32 tval = (s32)msec_to_cycles(test_args.long_wait_ms);
	u64 cval = DEF_CNT + msec_to_cycles(test_args.long_wait_ms);
	int i;

	for (i = 0; i < ARRAY_SIZE(irq_wait_method); i++) {
		irq_wait_method_t wm = irq_wait_method[i];

		test_timer_cval(timer, cval, wm, true, DEF_CNT);
		test_timer_tval(timer, tval, wm, true, DEF_CNT);
	}
}

static void guest_run_iteration(enum arch_timer timer)
{
	test_basic_functionality(timer);
	test_timers_sanity_checks(timer);

	test_timers_above_tval_max(timer);
	test_timers_in_the_past(timer);

	test_move_counters_ahead_of_timers(timer);
	test_move_counters_behind_timers(timer);
	test_reprogram_timers(timer);

	test_timers_fired_multiple_times(timer);

	test_timer_control_mask_then_unmask(timer);
	test_timer_control_masks(timer);
}

static void guest_code(enum arch_timer timer)
{
	int i;

	local_irq_disable();

	gic_init(GIC_V3, 1);

	timer_set_ctl(VIRTUAL, CTL_IMASK);
	timer_set_ctl(PHYSICAL, CTL_IMASK);

	gic_irq_enable(vtimer_irq);
	gic_irq_enable(ptimer_irq);
	local_irq_enable();

	for (i = 0; i < test_args.iterations; i++) {
		GUEST_SYNC(i);
		guest_run_iteration(timer);
	}

	test_long_timer_delays(timer);
	GUEST_DONE();
}

static cpu_set_t default_cpuset;

static u32 next_pcpu(void)
{
	u32 max = get_nprocs();
	u32 cur = sched_getcpu();
	u32 next = cur;
	cpu_set_t cpuset = default_cpuset;

	TEST_ASSERT(max > 1, "Need at least two physical cpus");

	do {
		next = (next + 1) % CPU_SETSIZE;
	} while (!CPU_ISSET(next, &cpuset));

	return next;
}

static void kvm_set_cntxct(struct kvm_vcpu *vcpu, u64 cnt,
			   enum arch_timer timer)
{
	if (timer == PHYSICAL)
		vcpu_set_reg(vcpu, KVM_REG_ARM_PTIMER_CNT, cnt);
	else
		vcpu_set_reg(vcpu, KVM_REG_ARM_TIMER_CNT, cnt);
}

static void handle_sync(struct kvm_vcpu *vcpu, struct ucall *uc)
{
	enum sync_cmd cmd = uc->args[1];
	u64 val = uc->args[2];
	enum arch_timer timer = uc->args[3];

	switch (cmd) {
	case SET_COUNTER_VALUE:
		kvm_set_cntxct(vcpu, val, timer);
		break;
	case USERSPACE_USLEEP:
		usleep(val);
		break;
	case USERSPACE_SCHED_YIELD:
		sched_yield();
		break;
	case USERSPACE_MIGRATE_SELF:
		pin_self_to_cpu(next_pcpu());
		break;
	default:
		break;
	}
}

static void test_run(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
{
	struct ucall uc;

	/* Start on CPU 0 */
	pin_self_to_cpu(0);

	while (true) {
		vcpu_run(vcpu);
		switch (get_ucall(vcpu, &uc)) {
		case UCALL_SYNC:
			handle_sync(vcpu, &uc);
			break;
		case UCALL_DONE:
			goto out;
		case UCALL_ABORT:
			REPORT_GUEST_ASSERT(uc);
			goto out;
		default:
			TEST_FAIL("Unexpected guest exit\n");
		}
	}

 out:
	return;
}

static void test_init_timer_irq(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
{
	ptimer_irq = vcpu_get_ptimer_irq(vcpu);
	vtimer_irq = vcpu_get_vtimer_irq(vcpu);

	sync_global_to_guest(vm, ptimer_irq);
	sync_global_to_guest(vm, vtimer_irq);

	pr_debug("ptimer_irq: %d; vtimer_irq: %d\n", ptimer_irq, vtimer_irq);
}

static void test_vm_create(struct kvm_vm **vm, struct kvm_vcpu **vcpu,
			   enum arch_timer timer)
{
	*vm = vm_create_with_one_vcpu(vcpu, guest_code);
	TEST_ASSERT(*vm, "Failed to create the test VM\n");

	vm_init_descriptor_tables(*vm);
	vm_install_exception_handler(*vm, VECTOR_IRQ_CURRENT,
				     guest_irq_handler);

	vcpu_init_descriptor_tables(*vcpu);
	vcpu_args_set(*vcpu, 1, timer);

	test_init_timer_irq(*vm, *vcpu);

	sync_global_to_guest(*vm, test_args);
	sync_global_to_guest(*vm, CVAL_MAX);
	sync_global_to_guest(*vm, DEF_CNT);
}

static void test_vm_cleanup(struct kvm_vm *vm)
{
	kvm_vm_free(vm);
}

static void test_print_help(char *name)
{
	pr_info("Usage: %s [-h] [-b] [-i iterations] [-l long_wait_ms] [-p] [-v]\n"
		, name);
	pr_info("\t-i: Number of iterations (default: %u)\n",
		NR_TEST_ITERS_DEF);
	pr_info("\t-b: Test both physical and virtual timers (default: true)\n");
	pr_info("\t-l: Delta (in ms) used for long wait time test (default: %u)\n",
	     LONG_WAIT_TEST_MS);
	pr_info("\t-w: Delta (in ms) used for wait times (default: %u)\n",
		WAIT_TEST_MS);
	pr_info("\t-p: Test physical timer (default: true)\n");
	pr_info("\t-v: Test virtual timer (default: true)\n");
	pr_info("\t-h: Print this help message\n");
}

static bool parse_args(int argc, char *argv[])
{
	int opt;

	while ((opt = getopt(argc, argv, "bhi:l:pvw:")) != -1) {
		switch (opt) {
		case 'b':
			test_args.test_physical = true;
			test_args.test_virtual = true;
			break;
		case 'i':
			test_args.iterations =
			    atoi_positive("Number of iterations", optarg);
			break;
		case 'l':
			test_args.long_wait_ms =
			    atoi_positive("Long wait time", optarg);
			break;
		case 'p':
			test_args.test_physical = true;
			test_args.test_virtual = false;
			break;
		case 'v':
			test_args.test_virtual = true;
			test_args.test_physical = false;
			break;
		case 'w':
			test_args.wait_ms = atoi_positive("Wait time", optarg);
			break;
		case 'h':
		default:
			goto err;
		}
	}

	return true;

 err:
	test_print_help(argv[0]);
	return false;
}

static void set_counter_defaults(void)
{
	const u64 MIN_ROLLOVER_SECS = 40ULL * 365 * 24 * 3600;
	u64 freq = read_sysreg(CNTFRQ_EL0);
	int width = ilog2(MIN_ROLLOVER_SECS * freq);

	width = clamp(width, 56, 64);
	CVAL_MAX = GENMASK_ULL(width - 1, 0);
	DEF_CNT = CVAL_MAX / 2;
}

int main(int argc, char *argv[])
{
	struct kvm_vcpu *vcpu;
	struct kvm_vm *vm;

	/* Tell stdout not to buffer its content */
	setbuf(stdout, NULL);

	TEST_REQUIRE(kvm_supports_vgic_v3());

	if (!parse_args(argc, argv))
		exit(KSFT_SKIP);

	sched_getaffinity(0, sizeof(default_cpuset), &default_cpuset);
	set_counter_defaults();

	if (test_args.test_virtual) {
		test_vm_create(&vm, &vcpu, VIRTUAL);
		test_run(vm, vcpu);
		test_vm_cleanup(vm);
	}

	if (test_args.test_physical) {
		test_vm_create(&vm, &vcpu, PHYSICAL);
		test_run(vm, vcpu);
		test_vm_cleanup(vm);
	}

	return 0;
}