Add an X86_PMU_FEATURE_* framework to simplify probing architectural
events on Intel PMUs, which require checking the length of a bit vector
and the _absence_ of a "feature" bit. Add helpers for both KVM and
"this CPU", and use the newfangled magic (along with X86_PROPERTY_*)
to clean up pmu_event_filter_test.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
.../selftests/kvm/include/x86_64/processor.h | 41 +++++++++++++++
.../kvm/x86_64/pmu_event_filter_test.c | 51 +++----------------
2 files changed, 48 insertions(+), 44 deletions(-)
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 209de48eb501..acad7184d1b6 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -201,6 +201,8 @@ struct kvm_x86_cpu_property {
#define X86_PROPERTY_MAX_BASIC_LEAF KVM_X86_CPU_PROPERTY(0, 0, EAX, 0, 31)
#define X86_PROPERTY_PMU_VERSION KVM_X86_CPU_PROPERTY(0xa, 0, EAX, 0, 7)
+#define X86_PROPERTY_PMU_NR_GP_COUNTERS KVM_X86_CPU_PROPERTY(0xa, 0, EAX, 8, 15)
+#define X86_PROPERTY_PMU_EBX_BIT_VECTOR_LENGTH KVM_X86_CPU_PROPERTY(0xa, 0, EAX, 24, 31)
#define X86_PROPERTY_XSTATE_MAX_SIZE_XCR0 KVM_X86_CPU_PROPERTY(0xd, 0, EBX, 0, 31)
#define X86_PROPERTY_XSTATE_MAX_SIZE KVM_X86_CPU_PROPERTY(0xd, 0, ECX, 0, 31)
@@ -221,6 +223,29 @@ struct kvm_x86_cpu_property {
#define X86_PROPERTY_MAX_CENTAUR_LEAF KVM_X86_CPU_PROPERTY(0xC0000000, 0, EAX, 0, 31)
+/*
+ * Intel's architectural PMU events are bizarre. They have a "feature" bit
+ * that indicates the feature is _not_ supported, and a property that states
+ * the length of the bit mask of unsupported features. A feature is supported
+ * if the size of the bit mask is larger than the "unavailable" bit, and said
+ * bit is not set.
+ *
+ * Wrap the "unavailable" feature to simplify checking whether or not a given
+ * architectural event is supported.
+ */
+struct kvm_x86_pmu_feature {
+ struct kvm_x86_cpu_feature anti_feature;
+};
+#define KVM_X86_PMU_FEATURE(name, __bit) \
+({ \
+ struct kvm_x86_pmu_feature feature = { \
+ .anti_feature = KVM_X86_CPU_FEATURE(0xa, 0, EBX, __bit), \
+ }; \
+ \
+ feature; \
+})
+
+#define X86_PMU_FEATURE_BRANCH_INSNS_RETIRED KVM_X86_PMU_FEATURE(BRANCH_INSNS_RETIRED, 5)
/* Page table bitfield declarations */
#define PTE_PRESENT_MASK BIT_ULL(0)
@@ -529,6 +554,14 @@ static __always_inline bool this_cpu_has_p(struct kvm_x86_cpu_property property)
return max_leaf >= property.function;
}
+static inline bool this_pmu_has(struct kvm_x86_pmu_feature feature)
+{
+ uint32_t nr_bits = this_cpu_property(X86_PROPERTY_PMU_EBX_BIT_VECTOR_LENGTH);
+
+ return nr_bits > feature.anti_feature.bit &&
+ !this_cpu_has(feature.anti_feature);
+}
+
#define SET_XMM(__var, __xmm) \
asm volatile("movq %0, %%"#__xmm : : "r"(__var) : #__xmm)
@@ -737,6 +770,14 @@ static __always_inline bool kvm_cpu_has_p(struct kvm_x86_cpu_property property)
return max_leaf >= property.function;
}
+static inline bool kvm_pmu_has(struct kvm_x86_pmu_feature feature)
+{
+ uint32_t nr_bits = kvm_cpu_property(X86_PROPERTY_PMU_EBX_BIT_VECTOR_LENGTH);
+
+ return nr_bits > feature.anti_feature.bit &&
+ !kvm_cpu_has(feature.anti_feature);
+}
+
static inline size_t kvm_cpuid2_size(int nr_entries)
{
return sizeof(struct kvm_cpuid2) +
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
index ea4e259a1e2e..5cc88ac31c45 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_event_filter_test.c
@@ -21,29 +21,6 @@
#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. */
@@ -380,30 +357,16 @@ static void test_pmu_config_disable(void (*guest_code)(void))
}
/*
- * 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.
+ * On Intel, check for a non-zero PMU version, at least one general-purpose
+ * counter per logical processor, and support for counting the number of branch
+ * instructions retired.
*/
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);
+ return is_intel_cpu() &&
+ kvm_cpu_property(X86_PROPERTY_PMU_VERSION) &&
+ kvm_cpu_property(X86_PROPERTY_PMU_NR_GP_COUNTERS) &&
+ kvm_pmu_has(X86_PMU_FEATURE_BRANCH_INSNS_RETIRED);
}
static bool is_zen1(uint32_t eax)
--
2.38.0.rc1.362.ged0d419d3c-goog
