Re: [RFC PATCH v3 09/58] perf: Add a EVENT_GUEST flag

[Peter Zijlstra <peterz@xxxxxxxxxxxxx>]

Can you rework this one along these lines?

---
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -975,6 +975,7 @@ struct perf_event_context {
 	 * Context clock, runs when context enabled.
 	 */
 	struct perf_time_ctx		time;
+	struct perf_time_ctx		timeguest;
 
 	/*
 	 * These fields let us detect when two contexts have both
@@ -1066,6 +1067,7 @@ struct bpf_perf_event_data_kern {
  */
 struct perf_cgroup_info {
 	struct perf_time_ctx		time;
+	struct perf_time_ctx		timeguest;
 	int				active;
 };
 
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -782,12 +782,44 @@ static inline int is_cgroup_event(struct
 	return event->cgrp != NULL;
 }
 
+static_assert(offsetof(struct perf_event, timeguest) -
+	      offsetof(struct perf_event, time) == 
+	      sizeof(struct perf_time_ctx));
+
+static_assert(offsetof(struct perf_cgroup_info, timeguest) -
+	      offsetof(struct perf_cgroup_info, time) ==
+	      sizeof(struct perf_time_ctx));
+
+static inline u64 __perf_event_time_ctx(struct perf_event *event,
+					struct perf_time_ctx *times)
+{
+	u64 time = times[0].time;
+	if (event->attr.exclude_guest)
+		time -= times[1].time;
+	return time;
+}
+
+static inline u64 __perf_event_time_ctx_now(struct perf_event *event,
+					    struct perf_time_ctx *times,
+					    u64 now)
+{
+	if (event->attr.exclude_guest) {
+		/*
+		 * (now + times[0].offset) - (now + times[1].offset) :=
+		 * times[0].offset - times[1].offset
+		 */
+		return READ_ONCE(times[0].offset) - READ_ONCE(times[1].offset);
+	}
+
+	return now + READ_ONCE(times[0].offset);
+}
+
 static inline u64 perf_cgroup_event_time(struct perf_event *event)
 {
 	struct perf_cgroup_info *t;
 
 	t = per_cpu_ptr(event->cgrp->info, event->cpu);
-	return t->time.time;
+	return __perf_event_time_ctx(event, &t->time);
 }
 
 static inline u64 perf_cgroup_event_time_now(struct perf_event *event, u64 now)
@@ -796,12 +828,12 @@ static inline u64 perf_cgroup_event_time
 
 	t = per_cpu_ptr(event->cgrp->info, event->cpu);
 	if (!__load_acquire(&t->active))
-		return t->time.time;
+		return __perf_event_time_ctx(event, &t->time);
 	now += READ_ONCE(t->time.offset);
-	return now;
+	return __perf_event_time_ctx_now(event, &t->time, now);
 }
 
-static inline void update_perf_time_ctx(struct perf_time_ctx *time, u64 now, bool adv)
+static inline void __update_perf_time_ctx(struct perf_time_ctx *time, u64 now, bool adv)
 {
 	if (adv)
 		time->time += now - time->stamp;
@@ -819,6 +851,13 @@ static inline void update_perf_time_ctx(
 	WRITE_ONCE(time->offset, time->time - time->stamp);
 }
 
+static inline void update_perf_time_ctx(struct perf_time_ctx *time, u64 now, bool adv)
+{
+	__update_perf_time_ctx(time + 0, now, adv);
+	if (__this_cpu_read(perf_in_guest))
+		__update_perf_time_ctx(time + 1, now, adv)
+}
+
 static inline void update_cgrp_time_from_cpuctx(struct perf_cpu_context *cpuctx, bool final)
 {
 	struct perf_cgroup *cgrp = cpuctx->cgrp;