[kvm-unit-tests PATCH v4 2/2] x86: Check platform vPMU capabilities before run lbr tests

[Yang Weijiang <weijiang.yang@xxxxxxxxx>]

Use new helper to check whether pmu is available and Perfmon/Debug
capbilities are supported before read MSR_IA32_PERF_CAPABILITIES to
avoid test failure. The issue can be captured when enable_pmu=0.

Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>

v4:
- Put the X86_FEATURE_PDCM to the right place. [Sean]
---
 lib/x86/processor.h |  1 +
 x86/pmu_lbr.c       | 32 +++++++++++++-------------------
 2 files changed, 14 insertions(+), 19 deletions(-)

diff --git a/lib/x86/processor.h b/lib/x86/processor.h
index 7b6ee92..7a35c7f 100644
--- a/lib/x86/processor.h
+++ b/lib/x86/processor.h
@@ -146,6 +146,7 @@ static inline bool is_intel(void)
  */
 #define	X86_FEATURE_MWAIT		(CPUID(0x1, 0, ECX, 3))
 #define	X86_FEATURE_VMX			(CPUID(0x1, 0, ECX, 5))
+#define	X86_FEATURE_PDCM		(CPUID(0x1, 0, ECX, 15))
 #define	X86_FEATURE_PCID		(CPUID(0x1, 0, ECX, 17))
 #define	X86_FEATURE_MOVBE		(CPUID(0x1, 0, ECX, 22))
 #define	X86_FEATURE_TSC_DEADLINE_TIMER	(CPUID(0x1, 0, ECX, 24))
diff --git a/x86/pmu_lbr.c b/x86/pmu_lbr.c
index 688634d..497df1e 100644
--- a/x86/pmu_lbr.c
+++ b/x86/pmu_lbr.c
@@ -15,6 +15,7 @@
 #define MSR_LBR_SELECT		0x000001c8
 
 volatile int count;
+u32 lbr_from, lbr_to;
 
 static noinline int compute_flag(int i)
 {
@@ -38,18 +39,6 @@ static noinline int lbr_test(void)
 	return 0;
 }
 
-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;
-} eax;
-
-u32 lbr_from, lbr_to;
-
 static void init_lbr(void *index)
 {
 	wrmsr(lbr_from + *(int *) index, 0);
@@ -63,7 +52,7 @@ static bool test_init_lbr_from_exception(u64 index)
 
 int main(int ac, char **av)
 {
-	struct cpuid id = cpuid(10);
+	u8 version = pmu_version();
 	u64 perf_cap;
 	int max, i;
 
@@ -74,19 +63,24 @@ int main(int ac, char **av)
 		return 0;
 	}
 
-	perf_cap = rdmsr(MSR_IA32_PERF_CAPABILITIES);
-	eax.full = id.a;
-
-	if (!eax.split.version_id) {
+	if (!version) {
 		printf("No pmu is detected!\n");
 		return report_summary();
 	}
+
+	if (!this_cpu_has(X86_FEATURE_PDCM)) {
+		printf("Perfmon/Debug Capabilities MSR isn't supported\n");
+		return report_summary();
+	}
+
+	perf_cap = rdmsr(MSR_IA32_PERF_CAPABILITIES);
+
 	if (!(perf_cap & PMU_CAP_LBR_FMT)) {
-		printf("No LBR is detected!\n");
+		printf("(Architectural) LBR is not supported.\n");
 		return report_summary();
 	}
 
-	printf("PMU version:		 %d\n", eax.split.version_id);
+	printf("PMU version:		 %d\n", version);
 	printf("LBR version:		 %ld\n", perf_cap & PMU_CAP_LBR_FMT);
 
 	/* Look for LBR from and to MSRs */
-- 
2.27.0