diff options
Diffstat (limited to 'tools/testing/selftests/kvm/x86_64/pmu_counters_test.c')
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/pmu_counters_test.c | 44 |
1 files changed, 29 insertions, 15 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c index 96446134c00b..698cb36989db 100644 --- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c +++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c @@ -7,15 +7,28 @@ #include "pmu.h" #include "processor.h" -/* Number of LOOP instructions for the guest measurement payload. */ -#define NUM_BRANCHES 10 +/* Number of iterations of the loop for the guest measurement payload. */ +#define NUM_LOOPS 10 + +/* Each iteration of the loop retires one branch instruction. */ +#define NUM_BRANCH_INSNS_RETIRED (NUM_LOOPS) + +/* + * Number of instructions in each loop. 1 CLFLUSH/CLFLUSHOPT/NOP, 1 MFENCE, + * 1 LOOP. + */ +#define NUM_INSNS_PER_LOOP 3 + /* * Number of "extra" instructions that will be counted, i.e. the number of - * instructions that are needed to set up the loop and then disabled the - * counter. 1 CLFLUSH/CLFLUSHOPT/NOP, 1 MFENCE, 2 MOV, 2 XOR, 1 WRMSR. + * instructions that are needed to set up the loop and then disable the + * counter. 2 MOV, 2 XOR, 1 WRMSR. */ -#define NUM_EXTRA_INSNS 7 -#define NUM_INSNS_RETIRED (NUM_BRANCHES + NUM_EXTRA_INSNS) +#define NUM_EXTRA_INSNS 5 + +/* Total number of instructions retired within the measured section. */ +#define NUM_INSNS_RETIRED (NUM_LOOPS * NUM_INSNS_PER_LOOP + NUM_EXTRA_INSNS) + static uint8_t kvm_pmu_version; static bool kvm_has_perf_caps; @@ -100,7 +113,7 @@ static void guest_assert_event_count(uint8_t idx, GUEST_ASSERT_EQ(count, NUM_INSNS_RETIRED); break; case INTEL_ARCH_BRANCHES_RETIRED_INDEX: - GUEST_ASSERT_EQ(count, NUM_BRANCHES); + GUEST_ASSERT_EQ(count, NUM_BRANCH_INSNS_RETIRED); break; case INTEL_ARCH_LLC_REFERENCES_INDEX: case INTEL_ARCH_LLC_MISSES_INDEX: @@ -120,7 +133,7 @@ static void guest_assert_event_count(uint8_t idx, } sanity_checks: - __asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES})); + __asm__ __volatile__("loop ." : "+c"((int){NUM_LOOPS})); GUEST_ASSERT_EQ(_rdpmc(pmc), count); wrmsr(pmc_msr, 0xdead); @@ -134,8 +147,8 @@ sanity_checks: * before the end of the sequence. * * If CLFUSH{,OPT} is supported, flush the cacheline containing (at least) the - * start of the loop to force LLC references and misses, i.e. to allow testing - * that those events actually count. + * CLFUSH{,OPT} instruction on each loop iteration to force LLC references and + * misses, i.e. to allow testing that those events actually count. * * If forced emulation is enabled (and specified), force emulation on a subset * of the measured code to verify that KVM correctly emulates instructions and @@ -145,10 +158,11 @@ sanity_checks: #define GUEST_MEASURE_EVENT(_msr, _value, clflush, FEP) \ do { \ __asm__ __volatile__("wrmsr\n\t" \ + " mov $" __stringify(NUM_LOOPS) ", %%ecx\n\t" \ + "1:\n\t" \ clflush "\n\t" \ "mfence\n\t" \ - "1: mov $" __stringify(NUM_BRANCHES) ", %%ecx\n\t" \ - FEP "loop .\n\t" \ + FEP "loop 1b\n\t" \ FEP "mov %%edi, %%ecx\n\t" \ FEP "xor %%eax, %%eax\n\t" \ FEP "xor %%edx, %%edx\n\t" \ @@ -163,9 +177,9 @@ do { \ wrmsr(pmc_msr, 0); \ \ if (this_cpu_has(X86_FEATURE_CLFLUSHOPT)) \ - GUEST_MEASURE_EVENT(_ctrl_msr, _value, "clflushopt 1f", FEP); \ + GUEST_MEASURE_EVENT(_ctrl_msr, _value, "clflushopt .", FEP); \ else if (this_cpu_has(X86_FEATURE_CLFLUSH)) \ - GUEST_MEASURE_EVENT(_ctrl_msr, _value, "clflush 1f", FEP); \ + GUEST_MEASURE_EVENT(_ctrl_msr, _value, "clflush .", FEP); \ else \ GUEST_MEASURE_EVENT(_ctrl_msr, _value, "nop", FEP); \ \ @@ -500,7 +514,7 @@ static void guest_test_fixed_counters(void) wrmsr(MSR_CORE_PERF_FIXED_CTR0 + i, 0); wrmsr(MSR_CORE_PERF_FIXED_CTR_CTRL, FIXED_PMC_CTRL(i, FIXED_PMC_KERNEL)); wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, FIXED_PMC_GLOBAL_CTRL_ENABLE(i)); - __asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES})); + __asm__ __volatile__("loop ." : "+c"((int){NUM_LOOPS})); wrmsr(MSR_CORE_PERF_GLOBAL_CTRL, 0); val = rdmsr(MSR_CORE_PERF_FIXED_CTR0 + i); |