perf, x86: Expose perf capability to other modules

KVM needs to know perf capability to decide which PMU it can expose to a
guest.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1320929850-10480-8-git-send-email-gleb@redhat.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/include/asm/perf_event.h

@@ -95,6 +95,15 @@ union cpuid10_edx {
 	unsigned int full;
 };
 
+struct x86_pmu_capability {
+	int		version;
+	int		num_counters_gp;
+	int		num_counters_fixed;
+	int		bit_width_gp;
+	int		bit_width_fixed;
+	unsigned int	events_mask;
+	int		events_mask_len;
+};
 
 /*
  * Fixed-purpose performance events:
@@ -216,6 +225,7 @@ struct perf_guest_switch_msr {
 };
 
 extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
+extern void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap);
 #else
 static inline perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
 {
@@ -223,6 +233,11 @@ static inline perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
 	return NULL;
 }
 
+static inline void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
+{
+	memset(cap, 0, sizeof(*cap));
+}
+
 static inline void perf_events_lapic_init(void)	{ }
 #endif
 

arch/x86/kernel/cpu/perf_event.c

@@ -1696,3 +1696,15 @@ unsigned long perf_misc_flags(struct pt_regs *regs)
 
 	return misc;
 }
+
+void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
+{
+	cap->version		= x86_pmu.version;
+	cap->num_counters_gp	= x86_pmu.num_counters;
+	cap->num_counters_fixed	= x86_pmu.num_counters_fixed;
+	cap->bit_width_gp	= x86_pmu.cntval_bits;
+	cap->bit_width_fixed	= x86_pmu.cntval_bits;
+	cap->events_mask	= (unsigned int)x86_pmu.events_maskl;
+	cap->events_mask_len	= x86_pmu.events_mask_len;
+}
+EXPORT_SYMBOL_GPL(perf_get_x86_pmu_capability);