KVM: arm64: selftests: Add arch_timer test

Add a KVM selftest to validate the arch_timer functionality.
Primarily, the test sets up periodic timer interrupts and
validates the basic architectural expectations upon its receipt.

The test provides command-line options to configure the period
of the timer, number of iterations, and number of vCPUs.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20211007233439.1826892-15-rananta@google.com

tools/testing/selftests/kvm/.gitignore

 # SPDX-License-Identifier: GPL-2.0-only
+/aarch64/arch_timer
 /aarch64/debug-exceptions
 /aarch64/get-reg-list
 /aarch64/psci_cpu_on_test

tools/testing/selftests/kvm/Makefile

@@ -86,6 +86,7 @@ TEST_GEN_PROGS_x86_64 += set_memory_region_test
 TEST_GEN_PROGS_x86_64 += steal_time
 TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test
 
+TEST_GEN_PROGS_aarch64 += aarch64/arch_timer
 TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
 TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/psci_cpu_on_test

tools/testing/selftests/kvm/aarch64/arch_timer.c

+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch_timer.c - Tests the aarch64 timer IRQ functionality
+ *
+ * The test validates both the virtual and physical timer IRQs using
+ * CVAL and TVAL registers. This consitutes the four stages in the test.
+ * The guest's main thread configures the timer interrupt for a stage
+ * and waits for it to fire, with a timeout equal to the timer period.
+ * It asserts that the timeout doesn't exceed the timer period.
+ *
+ * On the other hand, upon receipt of an interrupt, the guest's interrupt
+ * handler validates the interrupt by checking if the architectural state
+ * is in compliance with the specifications.
+ *
+ * The test provides command-line options to configure the timer's
+ * period (-p), number of vCPUs (-n), and iterations per stage (-i).
+ *
+ * Copyright (c) 2021, Google LLC.
+ */
+
+#define _GNU_SOURCE
+
+#include <stdlib.h>
+#include <pthread.h>
+#include <linux/kvm.h>
+#include <linux/sizes.h>
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "delay.h"
+#include "arch_timer.h"
+#include "gic.h"
+#include "vgic.h"
+
+#define NR_VCPUS_DEF			4
+#define NR_TEST_ITERS_DEF		5
+#define TIMER_TEST_PERIOD_MS_DEF	10
+#define TIMER_TEST_ERR_MARGIN_US	100
+
+struct test_args {
+	int nr_vcpus;
+	int nr_iter;
+	int timer_period_ms;
+};
+
+static struct test_args test_args = {
+	.nr_vcpus = NR_VCPUS_DEF,
+	.nr_iter = NR_TEST_ITERS_DEF,
+	.timer_period_ms = TIMER_TEST_PERIOD_MS_DEF,
+};
+
+#define msecs_to_usecs(msec)		((msec) * 1000LL)
+
+#define GICD_BASE_GPA			0x8000000ULL
+#define GICR_BASE_GPA			0x80A0000ULL
+
+enum guest_stage {
+	GUEST_STAGE_VTIMER_CVAL = 1,
+	GUEST_STAGE_VTIMER_TVAL,
+	GUEST_STAGE_PTIMER_CVAL,
+	GUEST_STAGE_PTIMER_TVAL,
+	GUEST_STAGE_MAX,
+};
+
+/* Shared variables between host and guest */
+struct test_vcpu_shared_data {
+	int nr_iter;
+	enum guest_stage guest_stage;
+	uint64_t xcnt;
+};
+
+struct test_vcpu {
+	uint32_t vcpuid;
+	pthread_t pt_vcpu_run;
+	struct kvm_vm *vm;
+};
+
+static struct test_vcpu test_vcpu[KVM_MAX_VCPUS];
+static struct test_vcpu_shared_data vcpu_shared_data[KVM_MAX_VCPUS];
+
+static int vtimer_irq, ptimer_irq;
+
+static void
+guest_configure_timer_action(struct test_vcpu_shared_data *shared_data)
+{
+	switch (shared_data->guest_stage) {
+	case GUEST_STAGE_VTIMER_CVAL:
+		timer_set_next_cval_ms(VIRTUAL, test_args.timer_period_ms);
+		shared_data->xcnt = timer_get_cntct(VIRTUAL);
+		timer_set_ctl(VIRTUAL, CTL_ENABLE);
+		break;
+	case GUEST_STAGE_VTIMER_TVAL:
+		timer_set_next_tval_ms(VIRTUAL, test_args.timer_period_ms);
+		shared_data->xcnt = timer_get_cntct(VIRTUAL);
+		timer_set_ctl(VIRTUAL, CTL_ENABLE);
+		break;
+	case GUEST_STAGE_PTIMER_CVAL:
+		timer_set_next_cval_ms(PHYSICAL, test_args.timer_period_ms);
+		shared_data->xcnt = timer_get_cntct(PHYSICAL);
+		timer_set_ctl(PHYSICAL, CTL_ENABLE);
+		break;
+	case GUEST_STAGE_PTIMER_TVAL:
+		timer_set_next_tval_ms(PHYSICAL, test_args.timer_period_ms);
+		shared_data->xcnt = timer_get_cntct(PHYSICAL);
+		timer_set_ctl(PHYSICAL, CTL_ENABLE);
+		break;
+	default:
+		GUEST_ASSERT(0);
+	}
+}
+
+static void guest_validate_irq(unsigned int intid,
+				struct test_vcpu_shared_data *shared_data)
+{
+	enum guest_stage stage = shared_data->guest_stage;
+	uint64_t xcnt = 0, xcnt_diff_us, cval = 0;
+	unsigned long xctl = 0;
+	unsigned int timer_irq = 0;
+
+	if (stage == GUEST_STAGE_VTIMER_CVAL ||
+		stage == GUEST_STAGE_VTIMER_TVAL) {
+		xctl = timer_get_ctl(VIRTUAL);
+		timer_set_ctl(VIRTUAL, CTL_IMASK);
+		xcnt = timer_get_cntct(VIRTUAL);
+		cval = timer_get_cval(VIRTUAL);
+		timer_irq = vtimer_irq;
+	} else if (stage == GUEST_STAGE_PTIMER_CVAL ||
+		stage == GUEST_STAGE_PTIMER_TVAL) {
+		xctl = timer_get_ctl(PHYSICAL);
+		timer_set_ctl(PHYSICAL, CTL_IMASK);
+		xcnt = timer_get_cntct(PHYSICAL);
+		cval = timer_get_cval(PHYSICAL);
+		timer_irq = ptimer_irq;
+	} else {
+		GUEST_ASSERT(0);
+	}
+
+	xcnt_diff_us = cycles_to_usec(xcnt - shared_data->xcnt);
+
+	/* Make sure we are dealing with the correct timer IRQ */
+	GUEST_ASSERT_2(intid == timer_irq, intid, timer_irq);
+
+	/* Basic 'timer condition met' check */
+	GUEST_ASSERT_3(xcnt >= cval, xcnt, cval, xcnt_diff_us);
+	GUEST_ASSERT_1(xctl & CTL_ISTATUS, xctl);
+}
+
+static void guest_irq_handler(struct ex_regs *regs)
+{
+	unsigned int intid = gic_get_and_ack_irq();
+	uint32_t cpu = guest_get_vcpuid();
+	struct test_vcpu_shared_data *shared_data = &vcpu_shared_data[cpu];
+
+	guest_validate_irq(intid, shared_data);
+
+	WRITE_ONCE(shared_data->nr_iter, shared_data->nr_iter + 1);
+
+	gic_set_eoi(intid);
+}
+
+static void guest_run_stage(struct test_vcpu_shared_data *shared_data,
+				enum guest_stage stage)
+{
+	uint32_t irq_iter, config_iter;
+
+	shared_data->guest_stage = stage;
+	shared_data->nr_iter = 0;
+
+	for (config_iter = 0; config_iter < test_args.nr_iter; config_iter++) {
+		/* Setup the next interrupt */
+		guest_configure_timer_action(shared_data);
+
+		/* Setup a timeout for the interrupt to arrive */
+		udelay(msecs_to_usecs(test_args.timer_period_ms) +
+			TIMER_TEST_ERR_MARGIN_US);
+
+		irq_iter = READ_ONCE(shared_data->nr_iter);
+		GUEST_ASSERT_2(config_iter + 1 == irq_iter,
+				config_iter + 1, irq_iter);
+	}
+}
+
+static void guest_code(void)
+{
+	uint32_t cpu = guest_get_vcpuid();
+	struct test_vcpu_shared_data *shared_data = &vcpu_shared_data[cpu];
+
+	local_irq_disable();
+
+	gic_init(GIC_V3, test_args.nr_vcpus,
+		(void *)GICD_BASE_GPA, (void *)GICR_BASE_GPA);
+
+	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();
+
+	guest_run_stage(shared_data, GUEST_STAGE_VTIMER_CVAL);
+	guest_run_stage(shared_data, GUEST_STAGE_VTIMER_TVAL);
+	guest_run_stage(shared_data, GUEST_STAGE_PTIMER_CVAL);
+	guest_run_stage(shared_data, GUEST_STAGE_PTIMER_TVAL);
+
+	GUEST_DONE();
+}
+
+static void *test_vcpu_run(void *arg)
+{
+	struct ucall uc;
+	struct test_vcpu *vcpu = arg;
+	struct kvm_vm *vm = vcpu->vm;
+	uint32_t vcpuid = vcpu->vcpuid;
+	struct test_vcpu_shared_data *shared_data = &vcpu_shared_data[vcpuid];
+
+	vcpu_run(vm, vcpuid);
+
+	switch (get_ucall(vm, vcpuid, &uc)) {
+	case UCALL_SYNC:
+	case UCALL_DONE:
+		break;
+	case UCALL_ABORT:
+		sync_global_from_guest(vm, *shared_data);
+		TEST_FAIL("%s at %s:%ld\n\tvalues: %lu, %lu; %lu, vcpu: %u; stage: %u; iter: %u",
+			(const char *)uc.args[0], __FILE__, uc.args[1],
+			uc.args[2], uc.args[3], uc.args[4], vcpuid,
+			shared_data->guest_stage, shared_data->nr_iter);
+		break;
+	default:
+		TEST_FAIL("Unexpected guest exit\n");
+	}
+
+	return NULL;
+}
+
+static void test_run(struct kvm_vm *vm)
+{
+	int i, ret;
+
+	for (i = 0; i < test_args.nr_vcpus; i++) {
+		ret = pthread_create(&test_vcpu[i].pt_vcpu_run, NULL,
+				test_vcpu_run, &test_vcpu[i]);
+		TEST_ASSERT(!ret, "Failed to create vCPU-%d pthread\n", i);
+	}
+
+	for (i = 0; i < test_args.nr_vcpus; i++)
+		pthread_join(test_vcpu[i].pt_vcpu_run, NULL);
+}
+
+static void test_init_timer_irq(struct kvm_vm *vm)
+{
+	/* Timer initid should be same for all the vCPUs, so query only vCPU-0 */
+	int vcpu0_fd = vcpu_get_fd(vm, 0);
+
+	kvm_device_access(vcpu0_fd, KVM_ARM_VCPU_TIMER_CTRL,
+			KVM_ARM_VCPU_TIMER_IRQ_PTIMER, &ptimer_irq, false);
+	kvm_device_access(vcpu0_fd, KVM_ARM_VCPU_TIMER_CTRL,
+			KVM_ARM_VCPU_TIMER_IRQ_VTIMER, &vtimer_irq, false);
+
+	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 struct kvm_vm *test_vm_create(void)
+{
+	struct kvm_vm *vm;
+	unsigned int i;
+	int nr_vcpus = test_args.nr_vcpus;
+
+	vm = vm_create_default_with_vcpus(nr_vcpus, 0, 0, guest_code, NULL);
+
+	vm_init_descriptor_tables(vm);
+	vm_install_exception_handler(vm, VECTOR_IRQ_CURRENT, guest_irq_handler);
+
+	for (i = 0; i < nr_vcpus; i++) {
+		vcpu_init_descriptor_tables(vm, i);
+
+		test_vcpu[i].vcpuid = i;
+		test_vcpu[i].vm = vm;
+	}
+
+	ucall_init(vm, NULL);
+	test_init_timer_irq(vm);
+	vgic_v3_setup(vm, nr_vcpus, GICD_BASE_GPA, GICR_BASE_GPA);
+
+	/* Make all the test's cmdline args visible to the guest */
+	sync_global_to_guest(vm, test_args);
+
+	return vm;
+}
+
+static void test_print_help(char *name)
+{
+	pr_info("Usage: %s [-h] [-n nr_vcpus] [-i iterations] [-p timer_period_ms]\n",
+		name);
+	pr_info("\t-n: Number of vCPUs to configure (default: %u; max: %u)\n",
+		NR_VCPUS_DEF, KVM_MAX_VCPUS);
+	pr_info("\t-i: Number of iterations per stage (default: %u)\n",
+		NR_TEST_ITERS_DEF);
+	pr_info("\t-p: Periodicity (in ms) of the guest timer (default: %u)\n",
+		TIMER_TEST_PERIOD_MS_DEF);
+	pr_info("\t-h: print this help screen\n");
+}
+
+static bool parse_args(int argc, char *argv[])
+{
+	int opt;
+
+	while ((opt = getopt(argc, argv, "hn:i:p:")) != -1) {
+		switch (opt) {
+		case 'n':
+			test_args.nr_vcpus = atoi(optarg);
+			if (test_args.nr_vcpus <= 0) {
+				pr_info("Positive value needed for -n\n");
+				goto err;
+			} else if (test_args.nr_vcpus > KVM_MAX_VCPUS) {
+				pr_info("Max allowed vCPUs: %u\n",
+					KVM_MAX_VCPUS);
+				goto err;
+			}
+			break;
+		case 'i':
+			test_args.nr_iter = atoi(optarg);
+			if (test_args.nr_iter <= 0) {
+				pr_info("Positive value needed for -i\n");
+				goto err;
+			}
+			break;
+		case 'p':
+			test_args.timer_period_ms = atoi(optarg);
+			if (test_args.timer_period_ms <= 0) {
+				pr_info("Positive value needed for -p\n");
+				goto err;
+			}
+			break;
+		case 'h':
+		default:
+			goto err;
+		}
+	}
+
+	return true;
+
+err:
+	test_print_help(argv[0]);
+	return false;
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_vm *vm;
+
+	/* Tell stdout not to buffer its content */
+	setbuf(stdout, NULL);
+
+	if (!parse_args(argc, argv))
+		exit(KSFT_SKIP);
+
+	vm = test_vm_create();
+	test_run(vm);
+	kvm_vm_free(vm);
+
+	return 0;
+}