2 files changed, 23 insertions, 12 deletions

diff --git a/arch/x86/events/intel/pt.c b/arch/x86/events/intel/pt.c
index c87d163c2917..1db7a51d9792 100644
--- a/arch/x86/events/intel/pt.c
+++ b/arch/x86/events/intel/pt.c
@@ -606,6 +606,7 @@ static inline phys_addr_t topa_pfn(struct topa *topa)
 
 static void pt_config_buffer(struct pt_buffer *buf)
 {
+	struct pt *pt = this_cpu_ptr(&pt_ctx);
 	u64 reg, mask;
 	void *base;
 
@@ -617,11 +618,17 @@ static void pt_config_buffer(struct pt_buffer *buf)
 		mask = (u64)buf->cur_idx;
 	}
 
-	wrmsrl(MSR_IA32_RTIT_OUTPUT_BASE, virt_to_phys(base));
+	reg = virt_to_phys(base);
+	if (pt->output_base != reg) {
+		pt->output_base = reg;
+		wrmsrl(MSR_IA32_RTIT_OUTPUT_BASE, reg);
+	}
 
 	reg = 0x7f | (mask << 7) | ((u64)buf->output_off << 32);
-
-	wrmsrl(MSR_IA32_RTIT_OUTPUT_MASK, reg);
+	if (pt->output_mask != reg) {
+		pt->output_mask = reg;
+		wrmsrl(MSR_IA32_RTIT_OUTPUT_MASK, reg);
+	}
 }
 
 /**
@@ -930,21 +937,21 @@ static void pt_handle_status(struct pt *pt)
  */
 static void pt_read_offset(struct pt_buffer *buf)
 {
-	u64 offset, base;
+	struct pt *pt = this_cpu_ptr(&pt_ctx);
 	struct topa_page *tp;
 
 	if (!buf->single) {
-		rdmsrl(MSR_IA32_RTIT_OUTPUT_BASE, base);
-		tp = phys_to_virt(base);
+		rdmsrl(MSR_IA32_RTIT_OUTPUT_BASE, pt->output_base);
+		tp = phys_to_virt(pt->output_base);
 		buf->cur = &tp->topa;
 	}
 
-	rdmsrl(MSR_IA32_RTIT_OUTPUT_MASK, offset);
+	rdmsrl(MSR_IA32_RTIT_OUTPUT_MASK, pt->output_mask);
 	/* offset within current output region */
-	buf->output_off = offset >> 32;
+	buf->output_off = pt->output_mask >> 32;
 	/* index of current output region within this table */
 	if (!buf->single)
-		buf->cur_idx = (offset & 0xffffff80) >> 7;
+		buf->cur_idx = (pt->output_mask & 0xffffff80) >> 7;
 }
 
 static struct topa_entry *
diff --git a/arch/x86/events/intel/pt.h b/arch/x86/events/intel/pt.h
index 3f7818221b95..96906a62aacd 100644
--- a/arch/x86/events/intel/pt.h
+++ b/arch/x86/events/intel/pt.h
@@ -113,16 +113,20 @@ struct pt_filters {
 
 /**
  * struct pt - per-cpu pt context
- * @handle:	perf output handle
+ * @handle:		perf output handle
  * @filters:		last configured filters
- * @handle_nmi:	do handle PT PMI on this cpu, there's an active event
- * @vmx_on:	1 if VMX is ON on this cpu
+ * @handle_nmi:		do handle PT PMI on this cpu, there's an active event
+ * @vmx_on:		1 if VMX is ON on this cpu
+ * @output_base:	cached RTIT_OUTPUT_BASE MSR value
+ * @output_mask:	cached RTIT_OUTPUT_MASK MSR value
  */
 struct pt {
 	struct perf_output_handle handle;
 	struct pt_filters	filters;
 	int			handle_nmi;
 	int			vmx_on;
+	u64			output_base;
+	u64			output_mask;
 };
 
 #endif /* __INTEL_PT_H__ */