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.
Co-developed-by: Wei Wang <[email protected]>
Signed-off-by: Wei Wang <[email protected]>
Signed-off-by: Like Xu <[email protected]>
---
arch/x86/events/intel/lbr.c | 20 ++++++++++++++++++++
arch/x86/include/asm/perf_event.h | 12 ++++++++++++
2 files changed, 32 insertions(+)
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 65113b16804a..2ed3f2a51bdf 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1343,3 +1343,23 @@ 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);
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index e855e9cf2c37..5d2c30f0df02 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -333,6 +333,13 @@ 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 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);
@@ -348,12 +355,17 @@ static inline void perf_check_microcode(void) { }
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
+extern int x86_perf_get_lbr(struct x86_pmu_lbr *lbr);
#else
static inline struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
{
*nr = 0;
return NULL;
}
+static inline int x86_perf_get_lbr(struct x86_pmu_lbr *lbr)
+{
+ return -1;
+}
#endif
#ifdef CONFIG_CPU_SUP_INTEL
--
2.21.3
The following commit has been merged into the perf/core branch of tip:
Commit-ID: b2d6504761a50b9493eb4b20f6e188b673f20c32
Gitweb: https://git.kernel.org/tip/b2d6504761a50b9493eb4b20f6e188b673f20c32
Author: Like Xu <[email protected]>
AuthorDate: Sat, 13 Jun 2020 16:09:48 +08:00
Committer: Peter Zijlstra <[email protected]>
CommitterDate: Thu, 02 Jul 2020 15:51:46 +02:00
perf/x86/lbr: Add interface to get LBR information
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: Like Xu <[email protected]>
Signed-off-by: Wei Wang <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
---
arch/x86/events/intel/lbr.c | 20 ++++++++++++++++++++
arch/x86/include/asm/perf_event.h | 12 ++++++++++++
2 files changed, 32 insertions(+)
diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c
index 65113b1..2ed3f2a 100644
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -1343,3 +1343,23 @@ 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);
diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index e855e9c..5d2c30f 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -333,6 +333,13 @@ 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 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);
@@ -348,12 +355,17 @@ static inline void perf_check_microcode(void) { }
#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_INTEL)
extern struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr);
+extern int x86_perf_get_lbr(struct x86_pmu_lbr *lbr);
#else
static inline struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr)
{
*nr = 0;
return NULL;
}
+static inline int x86_perf_get_lbr(struct x86_pmu_lbr *lbr)
+{
+ return -1;
+}
#endif
#ifdef CONFIG_CPU_SUP_INTEL