Intel: perf/x86/lbr: Add interface to get LBR information

mainline inclusion
from mainline-v5.9-rc1
commit b2d65047
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I47H3V
CVE: NA

--------------------------------

commit b2d65047 upstream
Backport summary: backport to kernel 4.19.57 for ICX perf topdown support

The LBR records msrs are model specific. The perf subsystem has already
obtained the base addresses of LBR records based on the cpu model.

Therefore, an interface is added to allow callers outside the perf
subsystem to obtain these LBR information. It's useful for hypervisors
to emulate the LBR feature for guests with less code.
Signed-off-by: NLike Xu <like.xu@linux.intel.com>
Signed-off-by: NWei Wang <wei.w.wang@intel.com>
Signed-off-by: NPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200613080958.132489-4-like.xu@linux.intel.comSigned-off-by: NYunying Sun <yunying.sun@intel.com>
Signed-off-by: NJackie Liu <liuyun01@kylinos.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NWei Li <liwei391@huawei.com>
Reviewed-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

arch/x86/events/intel/lbr.c

@@ -1310,3 +1310,23 @@ 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 - get the LBR records information
+ *
+ * @lbr: the caller's memory to store the LBR records information
+ *
+ * Returns: 0 indicates the LBR info has been successfully obtained
+ */
+int x86_perf_get_lbr(struct x86_pmu_lbr *lbr)
+{
+	int lbr_fmt = x86_pmu.intel_cap.lbr_format;
+
+	lbr->nr = x86_pmu.lbr_nr;
+	lbr->from = x86_pmu.lbr_from;
+	lbr->to = x86_pmu.lbr_to;
+	lbr->info = (lbr_fmt == LBR_FORMAT_INFO) ? MSR_LBR_INFO_0 : 0;
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(x86_perf_get_lbr);

arch/x86/include/asm/perf_event.h

@@ -322,6 +322,13 @@ struct perf_guest_switch_msr {
 	u64 host, guest;
 };
 
+struct x86_pmu_lbr {
+       unsigned int    nr;
+       unsigned int    from;
+       unsigned int    to;
+       unsigned int    info;
+};
+
 extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
 extern void perf_get_x86_pmu_capability(struct x86_pmu_capability *cap);
 extern void perf_check_microcode(void);
@@ -341,6 +348,15 @@ static inline void perf_events_lapic_init(void)	{ }
 static inline void perf_check_microcode(void) { }
 #endif
 
+#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
+extern int x86_perf_get_lbr(struct x86_pmu_lbr *lbr);
+#else
+static inline int x86_perf_get_lbr(struct x86_pmu_lbr *lbr)
+{
+       return -1;
+}
+#endif
+
 #ifdef CONFIG_CPU_SUP_INTEL
  extern void intel_pt_handle_vmx(int on);
 #endif