diff mbox series

[v8,02/14] perf/x86: add a function to get the addresses of the lbr stack msrs

Message ID 1565075774-26671-3-git-send-email-wei.w.wang@intel.com (mailing list archive)
State New, archived
Headers show
Series Guest LBR Enabling | expand

Commit Message

Wang, Wei W Aug. 6, 2019, 7:16 a.m. UTC 
The lbr stack msrs are model specific. The perf subsystem has already
assigned the abstracted msr address values based on the cpu model.
So add a function to enable callers outside the perf subsystem to get the
lbr stack addresses. This is useful for hypervisors to emulate the lbr
feature for the guest.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Wei Wang <wei.w.wang@intel.com>
---
 arch/x86/events/intel/lbr.c       | 23 +++++++++++++++++++++++
 arch/x86/include/asm/perf_event.h | 14 ++++++++++++++
 2 files changed, 37 insertions(+)
diff mbox series

Patch

diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 6f814a2..9b2d05c 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1311,3 +1311,26 @@  void intel_pmu_lbr_init_knl(void)
 	if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_LIP)
 		x86_pmu.intel_cap.lbr_format = LBR_FORMAT_EIP_FLAGS;
 }
+
+/**
+ * x86_perf_get_lbr_stack - get the lbr stack related msrs
+ *
+ * @stack: the caller's memory to get the lbr stack
+ *
+ * Returns: 0 indicates that the lbr stack has been successfully obtained.
+ */
+int x86_perf_get_lbr_stack(struct x86_perf_lbr_stack *stack)
+{
+	stack->nr = x86_pmu.lbr_nr;
+	stack->tos = x86_pmu.lbr_tos;
+	stack->from = x86_pmu.lbr_from;
+	stack->to = x86_pmu.lbr_to;
+
+	if (x86_pmu.intel_cap.lbr_format == LBR_FORMAT_INFO)
+		stack->info = MSR_LBR_INFO_0;
+	else
+		stack->info = 0;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(x86_perf_get_lbr_stack);
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 1392d5e..2606100 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -318,7 +318,16 @@  struct perf_guest_switch_msr {
 	u64 host, guest;
 };
 
+struct x86_perf_lbr_stack {
+	unsigned int	nr;
+	unsigned int	tos;
+	unsigned int	from;
+	unsigned int	to;
+	unsigned int	info;
+};
+
 extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
+extern int x86_perf_get_lbr_stack(struct x86_perf_lbr_stack *stack);
 extern void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap);
 extern void perf_check_microcode(void);
 extern int x86_perf_rdpmc_index(struct perf_event *event);
@@ -329,6 +338,11 @@  static inline struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
 	return NULL;
 }
 
+static inline int x86_perf_get_lbr_stack(struct x86_perf_lbr_stack *stack)
+{
+	return -1;
+}
+
 static inline void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap)
 {
 	memset(cap, 0, sizeof(*cap));