perf: Enhance perf to allow for guest statistic collection from host

Below patch introduces perf_guest_info_callbacks and related
register/unregister functions. Add more PERF_RECORD_MISC_XXX bits
meaning guest kernel and guest user space.

Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 22 insertions, 1 deletions

diff --git a/kernel/perf_event.c b/kernel/perf_event.c
index 07b7a435bf03..9dbe8cdaf145 100644
--- a/kernel/perf_event.c
+++ b/kernel/perf_event.c
@@ -2798,6 +2798,27 @@ void perf_arch_fetch_caller_regs(struct pt_regs *regs, unsigned long ip, int ski
 
 
 /*
+ * We assume there is only KVM supporting the callbacks.
+ * Later on, we might change it to a list if there is
+ * another virtualization implementation supporting the callbacks.
+ */
+struct perf_guest_info_callbacks *perf_guest_cbs;
+
+int perf_register_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+        perf_guest_cbs = cbs;
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_register_guest_info_callbacks);
+
+int perf_unregister_guest_info_callbacks(struct perf_guest_info_callbacks *cbs)
+{
+        perf_guest_cbs = NULL;
+        return 0;
+}
+EXPORT_SYMBOL_GPL(perf_unregister_guest_info_callbacks);
+
+/*
  * Output
  */
 static bool perf_output_space(struct perf_mmap_data *data, unsigned long tail,
@@ -3749,7 +3770,7 @@ void __perf_event_mmap(struct vm_area_struct *vma)
                 .event_id  = {
                         .header = {
                                 .type = PERF_RECORD_MMAP,
-                                .misc = 0,
+                                .misc = PERF_RECORD_MISC_USER,
                                 /* .size */
                         },
                         /* .pid */