Re: [PATCH v7 10/12] KVM: selftests: aarch64: Introduce vpmu_counter_access test

[Raghavendra Rao Ananta <rananta@google.com>]

Hi Eric,

On Tue, Oct 17, 2023 at 7:51 AM Eric Auger <eauger@redhat.com> wrote:
>
> Hi Raghavendra,
> On 10/10/23 01:08, Raghavendra Rao Ananta wrote:
> > From: Reiji Watanabe <reijiw@google.com>
> >
> > Introduce vpmu_counter_access test for arm64 platforms.
> > The test configures PMUv3 for a vCPU, sets PMCR_EL0.N for the vCPU,
> > and check if the guest can consistently see the same number of the
> > PMU event counters (PMCR_EL0.N) that userspace sets.
> > This test case is done with each of the PMCR_EL0.N values from
> > 0 to 31 (With the PMCR_EL0.N values greater than the host value,
> > the test expects KVM_SET_ONE_REG for the PMCR_EL0 to fail).
> >
> > Signed-off-by: Reiji Watanabe <reijiw@google.com>
> > Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
> > ---
> >  tools/testing/selftests/kvm/Makefile          |   1 +
> >  .../kvm/aarch64/vpmu_counter_access.c         | 247 ++++++++++++++++++
> >  2 files changed, 248 insertions(+)
> >  create mode 100644 tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c
> >
> > diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> > index a3bb36fb3cfc..416700aa196c 100644
> > --- a/tools/testing/selftests/kvm/Makefile
> > +++ b/tools/testing/selftests/kvm/Makefile
> > @@ -149,6 +149,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/smccc_filter
> >  TEST_GEN_PROGS_aarch64 += aarch64/vcpu_width_config
> >  TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
> >  TEST_GEN_PROGS_aarch64 += aarch64/vgic_irq
> > +TEST_GEN_PROGS_aarch64 += aarch64/vpmu_counter_access
> >  TEST_GEN_PROGS_aarch64 += access_tracking_perf_test
> >  TEST_GEN_PROGS_aarch64 += demand_paging_test
> >  TEST_GEN_PROGS_aarch64 += dirty_log_test
> > diff --git a/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c b/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c
> > new file mode 100644
> > index 000000000000..58949b17d76e
> > --- /dev/null
> > +++ b/tools/testing/selftests/kvm/aarch64/vpmu_counter_access.c
> > @@ -0,0 +1,247 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +/*
> > + * vpmu_counter_access - Test vPMU event counter access
> > + *
> > + * Copyright (c) 2022 Google LLC.
> 2023 ;-)
Will fix in v8.
> > + *
> > + * This test checks if the guest can see the same number of the PMU event
> > + * counters (PMCR_EL0.N) that userspace sets.
> > + * This test runs only when KVM_CAP_ARM_PMU_V3 is supported on the host.
> > + */
> > +#include <kvm_util.h>
> > +#include <processor.h>
> > +#include <test_util.h>
> > +#include <vgic.h>
> > +#include <perf/arm_pmuv3.h>
> > +#include <linux/bitfield.h>
> > +
> > +/* The max number of the PMU event counters (excluding the cycle counter) */
> > +#define ARMV8_PMU_MAX_GENERAL_COUNTERS       (ARMV8_PMU_MAX_COUNTERS - 1)
> > +
> > +struct vpmu_vm {
> > +     struct kvm_vm *vm;
> > +     struct kvm_vcpu *vcpu;
> > +     int gic_fd;
> > +};
> > +
> > +static struct vpmu_vm vpmu_vm;
> > +
> > +static uint64_t get_pmcr_n(uint64_t pmcr)
> > +{
> > +     return (pmcr >> ARMV8_PMU_PMCR_N_SHIFT) & ARMV8_PMU_PMCR_N_MASK;
> > +}
> > +
> > +static void set_pmcr_n(uint64_t *pmcr, uint64_t pmcr_n)
> > +{
> > +     *pmcr = *pmcr & ~(ARMV8_PMU_PMCR_N_MASK << ARMV8_PMU_PMCR_N_SHIFT);
> > +     *pmcr |= (pmcr_n << ARMV8_PMU_PMCR_N_SHIFT);
> > +}
> > +
> > +static void guest_sync_handler(struct ex_regs *regs)
> > +{
> > +     uint64_t esr, ec;
> > +
> > +     esr = read_sysreg(esr_el1);
> > +     ec = (esr >> ESR_EC_SHIFT) & ESR_EC_MASK;
> > +     __GUEST_ASSERT(0, "PC: 0x%lx; ESR: 0x%lx; EC: 0x%lx", regs->pc, esr, ec);
> > +}
> > +
> > +/*
> > + * The guest is configured with PMUv3 with @expected_pmcr_n number of
> > + * event counters.
> > + * Check if @expected_pmcr_n is consistent with PMCR_EL0.N.
> > + */
> > +static void guest_code(uint64_t expected_pmcr_n)
> > +{
> > +     uint64_t pmcr, pmcr_n;
> > +
> > +     __GUEST_ASSERT(expected_pmcr_n <= ARMV8_PMU_MAX_GENERAL_COUNTERS,
> > +                     "Expected PMCR.N: 0x%lx; ARMv8 general counters: 0x%lx",
> > +                     expected_pmcr_n, ARMV8_PMU_MAX_GENERAL_COUNTERS);
> > +
> > +     pmcr = read_sysreg(pmcr_el0);
> > +     pmcr_n = get_pmcr_n(pmcr);
> > +
> > +     /* Make sure that PMCR_EL0.N indicates the value userspace set */
> > +     __GUEST_ASSERT(pmcr_n == expected_pmcr_n,
> > +                     "Expected PMCR.N: 0x%lx, PMCR.N: 0x%lx",
> > +                     pmcr_n, expected_pmcr_n);
> > +
> > +     GUEST_DONE();
> > +}
> > +
> > +#define GICD_BASE_GPA        0x8000000ULL
> > +#define GICR_BASE_GPA        0x80A0000ULL
> > +
> > +/* Create a VM that has one vCPU with PMUv3 configured. */
> > +static void create_vpmu_vm(void *guest_code)
> > +{
> > +     struct kvm_vcpu_init init;
> > +     uint8_t pmuver, ec;
> > +     uint64_t dfr0, irq = 23;
> > +     struct kvm_device_attr irq_attr = {
> > +             .group = KVM_ARM_VCPU_PMU_V3_CTRL,
> > +             .attr = KVM_ARM_VCPU_PMU_V3_IRQ,
> > +             .addr = (uint64_t)&irq,
> > +     };
> > +     struct kvm_device_attr init_attr = {
> > +             .group = KVM_ARM_VCPU_PMU_V3_CTRL,
> > +             .attr = KVM_ARM_VCPU_PMU_V3_INIT,
> > +     };
> > +
> > +     /* The test creates the vpmu_vm multiple times. Ensure a clean state */
> > +     memset(&vpmu_vm, 0, sizeof(vpmu_vm));
> > +
> > +     vpmu_vm.vm = vm_create(1);
> > +     vm_init_descriptor_tables(vpmu_vm.vm);
> > +     for (ec = 0; ec < ESR_EC_NUM; ec++) {
> > +             vm_install_sync_handler(vpmu_vm.vm, VECTOR_SYNC_CURRENT, ec,
> > +                                     guest_sync_handler);
> > +     }
> > +
> > +     /* Create vCPU with PMUv3 */
> > +     vm_ioctl(vpmu_vm.vm, KVM_ARM_PREFERRED_TARGET, &init);
> > +     init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
> > +     vpmu_vm.vcpu = aarch64_vcpu_add(vpmu_vm.vm, 0, &init, guest_code);
> > +     vcpu_init_descriptor_tables(vpmu_vm.vcpu);
> > +     vpmu_vm.gic_fd = vgic_v3_setup(vpmu_vm.vm, 1, 64,
> > +                                     GICD_BASE_GPA, GICR_BASE_GPA);
> __TEST_REQUIRE(vpmu_vm.gic_fd >= 0, "Failed to create vgic-v3, skipping");
> as done in some other tests
>
I'll add this in v8.
> > +
> > +     /* Make sure that PMUv3 support is indicated in the ID register */
> > +     vcpu_get_reg(vpmu_vm.vcpu,
> > +                  KVM_ARM64_SYS_REG(SYS_ID_AA64DFR0_EL1), &dfr0);
> > +     pmuver = FIELD_GET(ARM64_FEATURE_MASK(ID_AA64DFR0_PMUVER), dfr0);
> > +     TEST_ASSERT(pmuver != ID_AA64DFR0_PMUVER_IMP_DEF &&
> > +                 pmuver >= ID_AA64DFR0_PMUVER_8_0,
> > +                 "Unexpected PMUVER (0x%x) on the vCPU with PMUv3", pmuver);
> > +
> > +     /* Initialize vPMU */
> > +     vcpu_ioctl(vpmu_vm.vcpu, KVM_SET_DEVICE_ATTR, &irq_attr);
> > +     vcpu_ioctl(vpmu_vm.vcpu, KVM_SET_DEVICE_ATTR, &init_attr);
> > +}
> > +
> > +static void destroy_vpmu_vm(void)
> > +{
> > +     close(vpmu_vm.gic_fd);
> > +     kvm_vm_free(vpmu_vm.vm);
> > +}
> > +
> > +static void run_vcpu(struct kvm_vcpu *vcpu, uint64_t pmcr_n)
> > +{
> > +     struct ucall uc;
> > +
> > +     vcpu_args_set(vcpu, 1, pmcr_n);
> > +     vcpu_run(vcpu);
> > +     switch (get_ucall(vcpu, &uc)) {
> > +     case UCALL_ABORT:
> > +             REPORT_GUEST_ASSERT(uc);
> > +             break;
> > +     case UCALL_DONE:
> > +             break;
> > +     default:
> > +             TEST_FAIL("Unknown ucall %lu", uc.cmd);
> > +             break;
> > +     }
> > +}
> > +
> > +/*
> > + * Create a guest with one vCPU, set the PMCR_EL0.N for the vCPU to @pmcr_n,
> > + * and run the test.
> > + */
> > +static void run_test(uint64_t pmcr_n)
> > +{
> > +     struct kvm_vcpu *vcpu;
> > +     uint64_t sp, pmcr;
> > +     struct kvm_vcpu_init init;
> > +
> > +     pr_debug("Test with pmcr_n %lu\n", pmcr_n);
> > +     create_vpmu_vm(guest_code);
> > +
> > +     vcpu = vpmu_vm.vcpu;
> > +
> > +     /* Save the initial sp to restore them later to run the guest again */
> > +     vcpu_get_reg(vcpu, ARM64_CORE_REG(sp_el1), &sp);
> > +
> > +     /* Update the PMCR_EL0.N with @pmcr_n */
> > +     vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), &pmcr);
> > +     set_pmcr_n(&pmcr, pmcr_n);
> > +     vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), pmcr);
> > +
> > +     run_vcpu(vcpu, pmcr_n);
> > +
> > +     /*
> > +      * Reset and re-initialize the vCPU, and run the guest code again to
> > +      * check if PMCR_EL0.N is preserved.
> > +      */
> > +     vm_ioctl(vpmu_vm.vm, KVM_ARM_PREFERRED_TARGET, &init);
> > +     init.features[0] |= (1 << KVM_ARM_VCPU_PMU_V3);
> > +     aarch64_vcpu_setup(vcpu, &init);
> > +     vcpu_init_descriptor_tables(vcpu);
> > +     vcpu_set_reg(vcpu, ARM64_CORE_REG(sp_el1), sp);
> > +     vcpu_set_reg(vcpu, ARM64_CORE_REG(regs.pc), (uint64_t)guest_code);
> > +
> > +     run_vcpu(vcpu, pmcr_n);
> > +
> > +     destroy_vpmu_vm();
> > +}
> > +
> > +/*
> > + * Create a guest with one vCPU, and attempt to set the PMCR_EL0.N for
> > + * the vCPU to @pmcr_n, which is larger than the host value.
> > + * The attempt should fail as @pmcr_n is too big to set for the vCPU.
> > + */
> > +static void run_error_test(uint64_t pmcr_n)
> > +{
> > +     struct kvm_vcpu *vcpu;
> > +     uint64_t pmcr, pmcr_orig;
> > +
> > +     pr_debug("Error test with pmcr_n %lu (larger than the host)\n", pmcr_n);
> > +     create_vpmu_vm(guest_code);
> > +     vcpu = vpmu_vm.vcpu;
> > +
> > +     vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), &pmcr_orig);
> > +     pmcr = pmcr_orig;
> > +
> > +     /*
> > +      * Setting a larger value of PMCR.N should not modify the field, and
> > +      * return a success.
> > +      */
> > +     set_pmcr_n(&pmcr, pmcr_n);
> > +     vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), pmcr);
> > +     vcpu_get_reg(vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), &pmcr);
> > +     TEST_ASSERT(pmcr_orig == pmcr,
> > +                 "PMCR.N modified by KVM to a larger value (PMCR: 0x%lx) for pmcr_n: 0x%lx\n",
> > +                 pmcr, pmcr_n);
> nit: you could introduce a set_pmcr_n() routine  which creates the
> vpmu_vm and set the PMCR.N and check whether the setting is applied. An
> arg could tell the helper whether this is supposed to fail. This could
> be used in both run_error_test and run_test which both mostly use the
> same code.
Good idea. I'll think about it..

Thank you.
Raghavendra
> > +
> > +     destroy_vpmu_vm();
> > +}
> > +
> > +/*
> > + * Return the default number of implemented PMU event counters excluding
> > + * the cycle counter (i.e. PMCR_EL0.N value) for the guest.
> > + */
> > +static uint64_t get_pmcr_n_limit(void)
> > +{
> > +     uint64_t pmcr;
> > +
> > +     create_vpmu_vm(guest_code);
> > +     vcpu_get_reg(vpmu_vm.vcpu, KVM_ARM64_SYS_REG(SYS_PMCR_EL0), &pmcr);
> > +     destroy_vpmu_vm();
> > +     return get_pmcr_n(pmcr);
> > +}
> > +
> > +int main(void)
> > +{
> > +     uint64_t i, pmcr_n;
> > +
> > +     TEST_REQUIRE(kvm_has_cap(KVM_CAP_ARM_PMU_V3));
> > +
> > +     pmcr_n = get_pmcr_n_limit();
> > +     for (i = 0; i <= pmcr_n; i++)
> > +             run_test(i);
> > +
> > +     for (i = pmcr_n + 1; i < ARMV8_PMU_MAX_COUNTERS; i++)
> > +             run_error_test(i);
> > +
> > +     return 0;
> > +}
>
> Besides this looks good to me.
>
> Thanks
>
> Eric
>