Re: [PATCH v4 15/18] KVM: arm64: selftests: Add arch_timer test

[Raghavendra Rao Ananta]

On Wed, Sep 8, 2021 at 10:51 PM Oliver Upton <oupton@xxxxxxxxxx> wrote:
>
> 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.
>
Correct me if I'm wrong, but aren't these the default INTIDs? And I
believe KVM follows the same. Or are you just concerned since these
are not defined as a part of UAPI, and have a potential to change?

Regards,
Raghavendra
> > +#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
> >