Messages in this thread | | | Date | Thu, 9 Nov 2023 15:51:21 +0800 | Subject | Re: [PATCH v7 19/19] KVM: selftests: Test PMC virtualization with forced emulation | From | "Mi, Dapeng" <> |
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On 11/8/2023 8:31 AM, Sean Christopherson wrote: > Extend the PMC counters test to use forced emulation to verify that KVM > emulates counter events for instructions retired and branches retired. > Force emulation for only a subset of the measured code to test that KVM > does the right thing when mixing perf events with emulated events. > > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > .../selftests/kvm/x86_64/pmu_counters_test.c | 44 +++++++++++++------ > 1 file changed, 30 insertions(+), 14 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 d775cc7e8fab..09332b3c0a69 100644 > --- a/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c > +++ b/tools/testing/selftests/kvm/x86_64/pmu_counters_test.c > @@ -21,6 +21,7 @@ > > static uint8_t kvm_pmu_version; > static bool kvm_has_perf_caps; > +static bool is_forced_emulation_enabled; > > static struct kvm_vm *pmu_vm_create_with_one_vcpu(struct kvm_vcpu **vcpu, > void *guest_code, > @@ -34,6 +35,7 @@ static struct kvm_vm *pmu_vm_create_with_one_vcpu(struct kvm_vcpu **vcpu, > vcpu_init_descriptor_tables(*vcpu); > > sync_global_to_guest(vm, kvm_pmu_version); > + sync_global_to_guest(vm, is_forced_emulation_enabled); > > /* > * Set PERF_CAPABILITIES before PMU version as KVM disallows enabling > @@ -138,37 +140,50 @@ static void guest_assert_event_count(uint8_t idx, > * 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. > + * > + * If forced emulation is enabled (and specified), force emulation on a subset > + * of the measured code to verify that KVM correctly emulates instructions and > + * branches retired events in conjunction with hardware also counting said > + * events. > */ > -#define GUEST_MEASURE_EVENT(_msr, _value, clflush) \ > +#define GUEST_MEASURE_EVENT(_msr, _value, clflush, FEP) \ > do { \ > __asm__ __volatile__("wrmsr\n\t" \ > clflush "\n\t" \ > "mfence\n\t" \ > "1: mov $" __stringify(NUM_BRANCHES) ", %%ecx\n\t" \ > - "loop .\n\t" \ > - "mov %%edi, %%ecx\n\t" \ > - "xor %%eax, %%eax\n\t" \ > - "xor %%edx, %%edx\n\t" \ > + FEP "loop .\n\t" \ > + FEP "mov %%edi, %%ecx\n\t" \ > + FEP "xor %%eax, %%eax\n\t" \ > + FEP "xor %%edx, %%edx\n\t" \ > "wrmsr\n\t" \ > :: "a"((uint32_t)_value), "d"(_value >> 32), \ > "c"(_msr), "D"(_msr) \ > ); \ > } while (0) > > +#define GUEST_TEST_EVENT(_idx, _event, _pmc, _pmc_msr, _ctrl_msr, _value, FEP) \ > +do { \ > + wrmsr(pmc_msr, 0); \ > + \ > + if (this_cpu_has(X86_FEATURE_CLFLUSHOPT)) \ > + GUEST_MEASURE_EVENT(_ctrl_msr, _value, "clflushopt 1f", FEP); \ > + else if (this_cpu_has(X86_FEATURE_CLFLUSH)) \ > + GUEST_MEASURE_EVENT(_ctrl_msr, _value, "clflush 1f", FEP); \ > + else \ > + GUEST_MEASURE_EVENT(_ctrl_msr, _value, "nop", FEP); \ > + \ > + guest_assert_event_count(_idx, _event, _pmc, _pmc_msr); \ > +} while (0) > + > static void __guest_test_arch_event(uint8_t idx, struct kvm_x86_pmu_feature event, > uint32_t pmc, uint32_t pmc_msr, > uint32_t ctrl_msr, uint64_t ctrl_msr_value) > { > - wrmsr(pmc_msr, 0); > + GUEST_TEST_EVENT(idx, event, pmc, pmc_msr, ctrl_msr, ctrl_msr_value, ""); > > - if (this_cpu_has(X86_FEATURE_CLFLUSHOPT)) > - GUEST_MEASURE_EVENT(ctrl_msr, ctrl_msr_value, "clflushopt 1f"); > - else if (this_cpu_has(X86_FEATURE_CLFLUSH)) > - GUEST_MEASURE_EVENT(ctrl_msr, ctrl_msr_value, "clflush 1f"); > - else > - GUEST_MEASURE_EVENT(ctrl_msr, ctrl_msr_value, "nop"); > - > - guest_assert_event_count(idx, event, pmc, pmc_msr); > + if (is_forced_emulation_enabled) > + GUEST_TEST_EVENT(idx, event, pmc, pmc_msr, ctrl_msr, ctrl_msr_value, KVM_FEP); > } > > #define X86_PMU_FEATURE_NULL \ > @@ -545,6 +560,7 @@ int main(int argc, char *argv[]) > > kvm_pmu_version = kvm_cpu_property(X86_PROPERTY_PMU_VERSION); > kvm_has_perf_caps = kvm_cpu_has(X86_FEATURE_PDCM); > + is_forced_emulation_enabled = kvm_is_forced_emulation_enabled(); > > test_intel_counters(); >
Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
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