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Diffstat (limited to '')
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c new file mode 100644 index 000000000000..ea4e259a1e2e --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c @@ -0,0 +1,479 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Test for x86 KVM_SET_PMU_EVENT_FILTER. + * + * Copyright (C) 2022, Google LLC. + * + * This work is licensed under the terms of the GNU GPL, version 2. + * + * Verifies the expected behavior of allow lists and deny lists for + * virtual PMU events. + */ + +#define _GNU_SOURCE /* for program_invocation_short_name */ +#include "test_util.h" +#include "kvm_util.h" +#include "processor.h" + +/* + * In lieu of copying perf_event.h into tools... + */ +#define ARCH_PERFMON_EVENTSEL_OS (1ULL << 17) +#define ARCH_PERFMON_EVENTSEL_ENABLE (1ULL << 22) + +union cpuid10_eax { + struct { + unsigned int version_id:8; + unsigned int num_counters:8; + unsigned int bit_width:8; + unsigned int mask_length:8; + } split; + unsigned int full; +}; + +union cpuid10_ebx { + struct { + unsigned int no_unhalted_core_cycles:1; + unsigned int no_instructions_retired:1; + unsigned int no_unhalted_reference_cycles:1; + unsigned int no_llc_reference:1; + unsigned int no_llc_misses:1; + unsigned int no_branch_instruction_retired:1; + unsigned int no_branch_misses_retired:1; + } split; + unsigned int full; +}; + +/* End of stuff taken from perf_event.h. */ + +/* Oddly, this isn't in perf_event.h. */ +#define ARCH_PERFMON_BRANCHES_RETIRED 5 + +#define NUM_BRANCHES 42 + +/* + * This is how the event selector and unit mask are stored in an AMD + * core performance event-select register. Intel's format is similar, + * but the event selector is only 8 bits. + */ +#define EVENT(select, umask) ((select & 0xf00UL) << 24 | (select & 0xff) | \ + (umask & 0xff) << 8) + +/* + * "Branch instructions retired", from the Intel SDM, volume 3, + * "Pre-defined Architectural Performance Events." + */ + +#define INTEL_BR_RETIRED EVENT(0xc4, 0) + +/* + * "Retired branch instructions", from Processor Programming Reference + * (PPR) for AMD Family 17h Model 01h, Revision B1 Processors, + * Preliminary Processor Programming Reference (PPR) for AMD Family + * 17h Model 31h, Revision B0 Processors, and Preliminary Processor + * Programming Reference (PPR) for AMD Family 19h Model 01h, Revision + * B1 Processors Volume 1 of 2. + */ + +#define AMD_ZEN_BR_RETIRED EVENT(0xc2, 0) + +/* + * This event list comprises Intel's eight architectural events plus + * AMD's "retired branch instructions" for Zen[123] (and possibly + * other AMD CPUs). + */ +static const uint64_t event_list[] = { + EVENT(0x3c, 0), + EVENT(0xc0, 0), + EVENT(0x3c, 1), + EVENT(0x2e, 0x4f), + EVENT(0x2e, 0x41), + EVENT(0xc4, 0), + EVENT(0xc5, 0), + EVENT(0xa4, 1), + AMD_ZEN_BR_RETIRED, +}; + +/* + * If we encounter a #GP during the guest PMU sanity check, then the guest + * PMU is not functional. Inform the hypervisor via GUEST_SYNC(0). + */ +static void guest_gp_handler(struct ex_regs *regs) +{ + GUEST_SYNC(0); +} + +/* + * Check that we can write a new value to the given MSR and read it back. + * The caller should provide a non-empty set of bits that are safe to flip. + * + * Return on success. GUEST_SYNC(0) on error. + */ +static void check_msr(uint32_t msr, uint64_t bits_to_flip) +{ + uint64_t v = rdmsr(msr) ^ bits_to_flip; + + wrmsr(msr, v); + if (rdmsr(msr) != v) + GUEST_SYNC(0); + + v ^= bits_to_flip; + wrmsr(msr, v); + if (rdmsr(msr) != v) + GUEST_SYNC(0); +} + +static void intel_guest_code(void) +{ + check_msr(MSR_CORE_PERF_GLOBAL_CTRL, 1); + check_msr(MSR_P6_EVNTSEL0, 0xffff); + check_msr(MSR_IA32_PMC0, 0xffff); + GUEST_SYNC(1); + + for (;;) { + uint64_t br0, br1; + + wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0); + wrmsr(MSR_P6_EVNTSEL0, ARCH_PERFMON_EVENTSEL_ENABLE | + ARCH_PERFMON_EVENTSEL_OS | INTEL_BR_RETIRED); + wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 1); + br0 = rdmsr(MSR_IA32_PMC0); + __asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES})); + br1 = rdmsr(MSR_IA32_PMC0); + GUEST_SYNC(br1 - br0); + } +} + +/* + * To avoid needing a check for CPUID.80000001:ECX.PerfCtrExtCore[bit 23], + * this code uses the always-available, legacy K7 PMU MSRs, which alias to + * the first four of the six extended core PMU MSRs. + */ +static void amd_guest_code(void) +{ + check_msr(MSR_K7_EVNTSEL0, 0xffff); + check_msr(MSR_K7_PERFCTR0, 0xffff); + GUEST_SYNC(1); + + for (;;) { + uint64_t br0, br1; + + wrmsr(MSR_K7_EVNTSEL0, 0); + wrmsr(MSR_K7_EVNTSEL0, ARCH_PERFMON_EVENTSEL_ENABLE | + ARCH_PERFMON_EVENTSEL_OS | AMD_ZEN_BR_RETIRED); + br0 = rdmsr(MSR_K7_PERFCTR0); + __asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES})); + br1 = rdmsr(MSR_K7_PERFCTR0); + GUEST_SYNC(br1 - br0); + } +} + +/* + * Run the VM to the next GUEST_SYNC(value), and return the value passed + * to the sync. Any other exit from the guest is fatal. + */ +static uint64_t run_vcpu_to_sync(struct kvm_vcpu *vcpu) +{ + struct kvm_run *run = vcpu->run; + struct ucall uc; + + vcpu_run(vcpu); + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, + "Exit_reason other than KVM_EXIT_IO: %u (%s)\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + get_ucall(vcpu, &uc); + TEST_ASSERT(uc.cmd == UCALL_SYNC, + "Received ucall other than UCALL_SYNC: %lu", uc.cmd); + return uc.args[1]; +} + +/* + * In a nested environment or if the vPMU is disabled, the guest PMU + * might not work as architected (accessing the PMU MSRs may raise + * #GP, or writes could simply be discarded). In those situations, + * there is no point in running these tests. The guest code will perform + * a sanity check and then GUEST_SYNC(success). In the case of failure, + * the behavior of the guest on resumption is undefined. + */ +static bool sanity_check_pmu(struct kvm_vcpu *vcpu) +{ + bool success; + + vm_install_exception_handler(vcpu->vm, GP_VECTOR, guest_gp_handler); + success = run_vcpu_to_sync(vcpu); + vm_install_exception_handler(vcpu->vm, GP_VECTOR, NULL); + + return success; +} + +static struct kvm_pmu_event_filter *alloc_pmu_event_filter(uint32_t nevents) +{ + struct kvm_pmu_event_filter *f; + int size = sizeof(*f) + nevents * sizeof(f->events[0]); + + f = malloc(size); + TEST_ASSERT(f, "Out of memory"); + memset(f, 0, size); + f->nevents = nevents; + return f; +} + + +static struct kvm_pmu_event_filter * +create_pmu_event_filter(const uint64_t event_list[], + int nevents, uint32_t action) +{ + struct kvm_pmu_event_filter *f; + int i; + + f = alloc_pmu_event_filter(nevents); + f->action = action; + for (i = 0; i < nevents; i++) + f->events[i] = event_list[i]; + + return f; +} + +static struct kvm_pmu_event_filter *event_filter(uint32_t action) +{ + return create_pmu_event_filter(event_list, + ARRAY_SIZE(event_list), + action); +} + +/* + * Remove the first occurrence of 'event' (if any) from the filter's + * event list. + */ +static struct kvm_pmu_event_filter *remove_event(struct kvm_pmu_event_filter *f, + uint64_t event) +{ + bool found = false; + int i; + + for (i = 0; i < f->nevents; i++) { + if (found) + f->events[i - 1] = f->events[i]; + else + found = f->events[i] == event; + } + if (found) + f->nevents--; + return f; +} + +static void test_without_filter(struct kvm_vcpu *vcpu) +{ + uint64_t count = run_vcpu_to_sync(vcpu); + + if (count != NUM_BRANCHES) + pr_info("%s: Branch instructions retired = %lu (expected %u)\n", + __func__, count, NUM_BRANCHES); + TEST_ASSERT(count, "Allowed PMU event is not counting"); +} + +static uint64_t test_with_filter(struct kvm_vcpu *vcpu, + struct kvm_pmu_event_filter *f) +{ + vm_ioctl(vcpu->vm, KVM_SET_PMU_EVENT_FILTER, f); + return run_vcpu_to_sync(vcpu); +} + +static void test_amd_deny_list(struct kvm_vcpu *vcpu) +{ + uint64_t event = EVENT(0x1C2, 0); + struct kvm_pmu_event_filter *f; + uint64_t count; + + f = create_pmu_event_filter(&event, 1, KVM_PMU_EVENT_DENY); + count = test_with_filter(vcpu, f); + + free(f); + if (count != NUM_BRANCHES) + pr_info("%s: Branch instructions retired = %lu (expected %u)\n", + __func__, count, NUM_BRANCHES); + TEST_ASSERT(count, "Allowed PMU event is not counting"); +} + +static void test_member_deny_list(struct kvm_vcpu *vcpu) +{ + struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_DENY); + uint64_t count = test_with_filter(vcpu, f); + + free(f); + if (count) + pr_info("%s: Branch instructions retired = %lu (expected 0)\n", + __func__, count); + TEST_ASSERT(!count, "Disallowed PMU Event is counting"); +} + +static void test_member_allow_list(struct kvm_vcpu *vcpu) +{ + struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_ALLOW); + uint64_t count = test_with_filter(vcpu, f); + + free(f); + if (count != NUM_BRANCHES) + pr_info("%s: Branch instructions retired = %lu (expected %u)\n", + __func__, count, NUM_BRANCHES); + TEST_ASSERT(count, "Allowed PMU event is not counting"); +} + +static void test_not_member_deny_list(struct kvm_vcpu *vcpu) +{ + struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_DENY); + uint64_t count; + + remove_event(f, INTEL_BR_RETIRED); + remove_event(f, AMD_ZEN_BR_RETIRED); + count = test_with_filter(vcpu, f); + free(f); + if (count != NUM_BRANCHES) + pr_info("%s: Branch instructions retired = %lu (expected %u)\n", + __func__, count, NUM_BRANCHES); + TEST_ASSERT(count, "Allowed PMU event is not counting"); +} + +static void test_not_member_allow_list(struct kvm_vcpu *vcpu) +{ + struct kvm_pmu_event_filter *f = event_filter(KVM_PMU_EVENT_ALLOW); + uint64_t count; + + remove_event(f, INTEL_BR_RETIRED); + remove_event(f, AMD_ZEN_BR_RETIRED); + count = test_with_filter(vcpu, f); + free(f); + if (count) + pr_info("%s: Branch instructions retired = %lu (expected 0)\n", + __func__, count); + TEST_ASSERT(!count, "Disallowed PMU Event is counting"); +} + +/* + * Verify that setting KVM_PMU_CAP_DISABLE prevents the use of the PMU. + * + * Note that KVM_CAP_PMU_CAPABILITY must be invoked prior to creating VCPUs. + */ +static void test_pmu_config_disable(void (*guest_code)(void)) +{ + struct kvm_vcpu *vcpu; + int r; + struct kvm_vm *vm; + + r = kvm_check_cap(KVM_CAP_PMU_CAPABILITY); + if (!(r & KVM_PMU_CAP_DISABLE)) + return; + + vm = vm_create(1); + + vm_enable_cap(vm, KVM_CAP_PMU_CAPABILITY, KVM_PMU_CAP_DISABLE); + + vcpu = vm_vcpu_add(vm, 0, guest_code); + vm_init_descriptor_tables(vm); + vcpu_init_descriptor_tables(vcpu); + + TEST_ASSERT(!sanity_check_pmu(vcpu), + "Guest should not be able to use disabled PMU."); + + kvm_vm_free(vm); +} + +/* + * Check for a non-zero PMU version, at least one general-purpose + * counter per logical processor, an EBX bit vector of length greater + * than 5, and EBX[5] clear. + */ +static bool check_intel_pmu_leaf(const struct kvm_cpuid_entry2 *entry) +{ + union cpuid10_eax eax = { .full = entry->eax }; + union cpuid10_ebx ebx = { .full = entry->ebx }; + + return eax.split.version_id && eax.split.num_counters > 0 && + eax.split.mask_length > ARCH_PERFMON_BRANCHES_RETIRED && + !ebx.split.no_branch_instruction_retired; +} + +/* + * Note that CPUID leaf 0xa is Intel-specific. This leaf should be + * clear on AMD hardware. + */ +static bool use_intel_pmu(void) +{ + const struct kvm_cpuid_entry2 *entry; + + entry = kvm_get_supported_cpuid_entry(0xa); + return is_intel_cpu() && check_intel_pmu_leaf(entry); +} + +static bool is_zen1(uint32_t eax) +{ + return x86_family(eax) == 0x17 && x86_model(eax) <= 0x0f; +} + +static bool is_zen2(uint32_t eax) +{ + return x86_family(eax) == 0x17 && + x86_model(eax) >= 0x30 && x86_model(eax) <= 0x3f; +} + +static bool is_zen3(uint32_t eax) +{ + return x86_family(eax) == 0x19 && x86_model(eax) <= 0x0f; +} + +/* + * Determining AMD support for a PMU event requires consulting the AMD + * PPR for the CPU or reference material derived therefrom. The AMD + * test code herein has been verified to work on Zen1, Zen2, and Zen3. + * + * Feel free to add more AMD CPUs that are documented to support event + * select 0xc2 umask 0 as "retired branch instructions." + */ +static bool use_amd_pmu(void) +{ + const struct kvm_cpuid_entry2 *entry; + + entry = kvm_get_supported_cpuid_entry(1); + return is_amd_cpu() && + (is_zen1(entry->eax) || + is_zen2(entry->eax) || + is_zen3(entry->eax)); +} + +int main(int argc, char *argv[]) +{ + void (*guest_code)(void); + struct kvm_vcpu *vcpu; + struct kvm_vm *vm; + + /* Tell stdout not to buffer its content */ + setbuf(stdout, NULL); + + TEST_REQUIRE(kvm_has_cap(KVM_CAP_PMU_EVENT_FILTER)); + + TEST_REQUIRE(use_intel_pmu() || use_amd_pmu()); + guest_code = use_intel_pmu() ? intel_guest_code : amd_guest_code; + + vm = vm_create_with_one_vcpu(&vcpu, guest_code); + + vm_init_descriptor_tables(vm); + vcpu_init_descriptor_tables(vcpu); + + TEST_REQUIRE(sanity_check_pmu(vcpu)); + + if (use_amd_pmu()) + test_amd_deny_list(vcpu); + + test_without_filter(vcpu); + test_member_deny_list(vcpu); + test_member_allow_list(vcpu); + test_not_member_deny_list(vcpu); + test_not_member_allow_list(vcpu); + + kvm_vm_free(vm); + + test_pmu_config_disable(guest_code); + + return 0; +} |