[kvm-unit-tests PATCH v4 14/24] x86/pmu: Read cpuid(10) in the pmu_init() to reduce VM-Exit

[Like Xu <like.xu.linux@xxxxxxxxx>]

From: Like Xu <likexu@xxxxxxxxxxx>

The type of CPUID accessors can also go in the common pmu. Re-reading
cpuid(10) each time when needed, adding the overhead of eimulating
CPUID isn't meaningless in the grand scheme of the test.

A common "PMU init" routine would allow the library to provide helpers
access to more PMU common information.

Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
---
 lib/x86/pmu.c |  7 +++++++
 lib/x86/pmu.h | 26 +++++++++++++-------------
 lib/x86/smp.c |  2 ++
 3 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/lib/x86/pmu.c b/lib/x86/pmu.c
index 9d048ab..e8b9ae9 100644
--- a/lib/x86/pmu.c
+++ b/lib/x86/pmu.c
@@ -1 +1,8 @@
 #include "pmu.h"
+
+struct cpuid cpuid_10;
+
+void pmu_init(void)
+{
+    cpuid_10 = cpuid(10);
+}
\ No newline at end of file
diff --git a/lib/x86/pmu.h b/lib/x86/pmu.h
index 078a974..7f4e797 100644
--- a/lib/x86/pmu.h
+++ b/lib/x86/pmu.h
@@ -33,9 +33,13 @@
 #define EVNTSEL_INT	(1 << EVNTSEL_INT_SHIFT)
 #define EVNTSEL_INV	(1 << EVNTSEL_INV_SHIF)
 
+extern struct cpuid cpuid_10;
+
+void pmu_init(void);
+
 static inline u8 pmu_version(void)
 {
-	return cpuid(10).a & 0xff;
+	return cpuid_10.a & 0xff;
 }
 
 static inline bool this_cpu_has_pmu(void)
@@ -50,35 +54,31 @@ static inline bool this_cpu_has_perf_global_ctrl(void)
 
 static inline u8 pmu_nr_gp_counters(void)
 {
-	return (cpuid(10).a >> 8) & 0xff;
+	return (cpuid_10.a >> 8) & 0xff;
 }
 
 static inline u8 pmu_gp_counter_width(void)
 {
-	return (cpuid(10).a >> 16) & 0xff;
+	return (cpuid_10.a >> 16) & 0xff;
 }
 
 static inline u8 pmu_gp_counter_mask_length(void)
 {
-	return (cpuid(10).a >> 24) & 0xff;
+	return (cpuid_10.a >> 24) & 0xff;
 }
 
 static inline u8 pmu_nr_fixed_counters(void)
 {
-	struct cpuid id = cpuid(10);
-
-	if ((id.a & 0xff) > 1)
-		return id.d & 0x1f;
+	if ((cpuid_10.a & 0xff) > 1)
+		return cpuid_10.d & 0x1f;
 	else
 		return 0;
 }
 
 static inline u8 pmu_fixed_counter_width(void)
 {
-	struct cpuid id = cpuid(10);
-
-	if ((id.a & 0xff) > 1)
-		return (id.d >> 5) & 0xff;
+	if ((cpuid_10.a & 0xff) > 1)
+		return (cpuid_10.d >> 5) & 0xff;
 	else
 		return 0;
 }
@@ -86,7 +86,7 @@ static inline u8 pmu_fixed_counter_width(void)
 static inline bool pmu_gp_counter_is_available(int i)
 {
 	/* CPUID.0xA.EBX bit is '1 if they counter is NOT available. */
-	return !(cpuid(10).b & BIT(i));
+	return !(cpuid_10.b & BIT(i));
 }
 
 static inline u64 this_cpu_perf_capabilities(void)
diff --git a/lib/x86/smp.c b/lib/x86/smp.c
index b9b91c7..29197fc 100644
--- a/lib/x86/smp.c
+++ b/lib/x86/smp.c
@@ -4,6 +4,7 @@
 #include <asm/barrier.h>
 
 #include "processor.h"
+#include "pmu.h"
 #include "atomic.h"
 #include "smp.h"
 #include "apic.h"
@@ -155,6 +156,7 @@ void smp_init(void)
 		on_cpu(i, setup_smp_id, 0);
 
 	atomic_inc(&active_cpus);
+	pmu_init();
 }
 
 static void do_reset_apic(void *data)
-- 
2.38.1