Re: [PATCH v4 15/18] KVM: arm64: selftests: Add arch_timer test
From: Oliver Upton
Date: Thu Sep 09 2021 - 01:51:34 EST
On Thu, Sep 09, 2021 at 01:38:15AM +0000, Raghavendra Rao Ananta wrote:
> 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@xxxxxxxxxx>
> Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/.gitignore | 1 +
> tools/testing/selftests/kvm/Makefile | 1 +
> .../selftests/kvm/aarch64/arch_timer.c | 351 ++++++++++++++++++
> 3 files changed, 353 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/aarch64/arch_timer.c
>
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 98053d3afbda..c6058df0cd18 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -1,4 +1,5 @@
> # SPDX-License-Identifier: GPL-2.0-only
> +/aarch64/arch_timer
> /aarch64/debug-exceptions
> /aarch64/get-reg-list
> /aarch64/psci_cpu_on_test
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 8342f65c1d96..46d43e706b20 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -84,6 +84,7 @@ 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
> diff --git a/tools/testing/selftests/kvm/aarch64/arch_timer.c b/tools/testing/selftests/kvm/aarch64/arch_timer.c
> new file mode 100644
> index 000000000000..6141c387e6dc
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/aarch64/arch_timer.c
> @@ -0,0 +1,351 @@
> +// 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 VTIMER_IRQ 27
> +#define PTIMER_IRQ 30
I don't know if these are guaranteed, necessarily. Probably safest to
determine the IRQ# from the KVM_ARM_VCPU_TIMER_IRQ_{P,V}TIMER vCPU
device attributes. Either that or write these values to the attributes.
> +#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 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 = 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 = 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 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);
> + vm_vcpuid_map_init(vm);
> + vgic_v3_setup(vm, 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;
> +}
> --
> 2.33.0.153.gba50c8fa24-goog
>