[PATCH 2/7] KVM: selftests: Test Intel PMU architectural events on fixed counters

[Like Xu]

From: Jinrong Liang <cloudliang@xxxxxxxxxxx>

Update test to cover Intel PMU architectural events on fixed counters.
Per Intel SDM, PMU users can also count architecture performance events
on fixed counters (specifically, FIXED_CTR0 for the retired instructions
and FIXED_CTR1 for cpu core cycles event). Therefore, if guest's CPUID
indicates that an architecture event is not available, the corresponding
fixed counter will also not count that event.

Co-developed-by: Like Xu <likexu@xxxxxxxxxxx>
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
Signed-off-by: Jinrong Liang <cloudliang@xxxxxxxxxxx>
---
 .../selftests/kvm/x86_64/pmu_cpuid_test.c     | 37 +++++++++++++++++--
 1 file changed, 33 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/pmu_cpuid_test.c b/tools/testing/selftests/kvm/x86_64/pmu_cpuid_test.c
index faab0a91e191..75434aa2a0ec 100644
--- a/tools/testing/selftests/kvm/x86_64/pmu_cpuid_test.c
+++ b/tools/testing/selftests/kvm/x86_64/pmu_cpuid_test.c
@@ -25,6 +25,9 @@
 #define GP_CTR_NUM_MASK GENMASK_ULL(15, GP_CTR_NUM_OFS_BIT)
 #define EVT_LEN_OFS_BIT 24
 #define EVT_LEN_MASK GENMASK_ULL(31, EVT_LEN_OFS_BIT)
+#define INTEL_PMC_IDX_FIXED 32
+#define RDPMC_FIXED_BASE BIT_ULL(30)
+#define FIXED_CTR_NUM_MASK GENMASK_ULL(4, 0)
 
 #define ARCH_EVENT(select, umask) (((select) & 0xff) | ((umask) & 0xff) << 8)
 
@@ -43,6 +46,14 @@ static const uint64_t arch_events[] = {
 	[7] = ARCH_EVENT(0xa4, 0x1), /* Topdown Slots */
 };
 
+/* Association of Fixed Counters with Architectural Performance Events */
+static int fixed_events[] = {1, 0, 7};
+
+static uint64_t evt_code_for_fixed_ctr(uint8_t idx)
+{
+	return arch_events[fixed_events[idx]];
+}
+
 static struct kvm_vcpu *new_vcpu(void *guest_code)
 {
 	struct kvm_vm *vm;
@@ -88,8 +99,8 @@ static bool first_uc_arg_non_zero(struct ucall *uc, void *data)
 }
 
 static void intel_guest_run_arch_event(uint8_t version, uint8_t max_gp_num,
-				       bool supported, uint32_t ctr_base_msr,
-				       uint64_t evt_code)
+				       uint8_t max_fixed_num, bool supported,
+				       uint32_t ctr_base_msr, uint64_t evt_code)
 {
 	uint32_t global_msr = MSR_CORE_PERF_GLOBAL_CTRL;
 	unsigned int i;
@@ -108,6 +119,23 @@ static void intel_guest_run_arch_event(uint8_t version, uint8_t max_gp_num,
 		GUEST_SYNC(supported == !!_rdpmc(i));
 	}
 
+	/* No need to test independent arch events on fixed counters. */
+	if (version > 1 && max_fixed_num > 1 &&
+	    (evt_code == evt_code_for_fixed_ctr(0) ||
+	     evt_code == evt_code_for_fixed_ctr(1))) {
+		i = (evt_code == evt_code_for_fixed_ctr(0)) ? 0 : 1;
+
+		wrmsr(MSR_CORE_PERF_FIXED_CTR0 + i, 0);
+		wrmsr(MSR_CORE_PERF_FIXED_CTR_CTRL, BIT_ULL(4 * i));
+		wrmsr(global_msr, BIT_ULL(INTEL_PMC_IDX_FIXED + i));
+
+		__asm__ __volatile__("loop ." : "+c"((int){NUM_BRANCHES}));
+
+		wrmsr(global_msr, 0);
+
+		GUEST_SYNC(supported == !!_rdpmc(RDPMC_FIXED_BASE | i));
+	}
+
 	GUEST_DONE();
 }
 
@@ -131,9 +159,10 @@ static void test_arch_events_setup(struct kvm_vcpu *vcpu, uint8_t evt_vector,
 	is_supported = !(entry->ebx & BIT_ULL(idx)) &&
 		(((entry->eax & EVT_LEN_MASK) >> EVT_LEN_OFS_BIT) > idx);
 
-	vcpu_args_set(vcpu, 5, entry->eax & PMU_VERSION_MASK,
+	vcpu_args_set(vcpu, 6, entry->eax & PMU_VERSION_MASK,
 		      (entry->eax & GP_CTR_NUM_MASK) >> GP_CTR_NUM_OFS_BIT,
-		      is_supported, ctr_msr, arch_events[idx]);
+		      (entry->edx & FIXED_CTR_NUM_MASK), is_supported,
+		      ctr_msr, arch_events[idx]);
 }
 
 static void intel_check_arch_event_is_unavl(uint8_t idx)
-- 
2.40.0