Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 13 Jun 2022 16:35:11 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Ravi Bangoria <ravi.bangoria@amd.com>
Cc:     acme@kernel.org, alexander.shishkin@linux.intel.com,
        jolsa@redhat.com, namhyung@kernel.org, songliubraving@fb.com,
        eranian@google.com, alexey.budankov@linux.intel.com,
        ak@linux.intel.com, mark.rutland@arm.com, megha.dey@intel.com,
        frederic@kernel.org, maddy@linux.ibm.com, irogers@google.com,
        kim.phillips@amd.com, linux-kernel@vger.kernel.org,
        santosh.shukla@amd.com
Subject: Re: [RFC v2] perf: Rewrite core context handling
Message-ID: <YqdLH+ZU/sf4n0pa@hirez.programming.kicks-ass.net>
References: <20220113134743.1292-1-ravi.bangoria@amd.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220113134743.1292-1-ravi.bangoria@amd.com>
Precedence: bulk


Right, so sorry for being incredibly tardy on this. Find below the
patch fwd ported to something recent.

I'll reply to this with fixes and comments.

---
--- a/arch/powerpc/perf/core-book3s.c
+++ b/arch/powerpc/perf/core-book3s.c
@@ -132,7 +132,7 @@ static unsigned long ebb_switch_in(bool
 
 static inline void power_pmu_bhrb_enable(struct perf_event *event) {}
 static inline void power_pmu_bhrb_disable(struct perf_event *event) {}
-static void power_pmu_sched_task(struct perf_event_context *ctx, bool sched_in) {}
+static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) {}
 static inline void power_pmu_bhrb_read(struct perf_event *event, struct cpu_hw_events *cpuhw) {}
 static void pmao_restore_workaround(bool ebb) { }
 #endif /* CONFIG_PPC32 */
@@ -451,7 +451,7 @@ static void power_pmu_bhrb_disable(struc
 /* Called from ctxsw to prevent one process's branch entries to
  * mingle with the other process's entries during context switch.
  */
-static void power_pmu_sched_task(struct perf_event_context *ctx, bool sched_in)
+static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
 {
 	if (!ppmu->bhrb_nr)
 		return;
--- a/arch/x86/events/amd/brs.c
+++ b/arch/x86/events/amd/brs.c
@@ -317,7 +317,7 @@ static void amd_brs_poison_buffer(void)
  * On ctxswin, sched_in = true, called after the PMU has started
  * On ctxswout, sched_in = false, called before the PMU is stopped
  */
-void amd_pmu_brs_sched_task(struct perf_event_context *ctx, bool sched_in)
+void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 
--- a/arch/x86/events/amd/core.c
+++ b/arch/x86/events/amd/core.c
@@ -1248,11 +1248,11 @@ static ssize_t amd_event_sysfs_show(char
 	return x86_event_sysfs_show(page, config, event);
 }
 
-static void amd_pmu_sched_task(struct perf_event_context *ctx,
+static void amd_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx,
 				 bool sched_in)
 {
 	if (sched_in && x86_pmu.lbr_nr)
-		amd_pmu_brs_sched_task(ctx, sched_in);
+		amd_pmu_brs_sched_task(pmu_ctx, sched_in);
 }
 
 static u64 amd_pmu_limit_period(struct perf_event *event, u64 left)
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2067,13 +2067,14 @@ void x86_pmu_show_pmu_cap(int num_counte
  */
 void x86_pmu_update_cpu_context(struct pmu *pmu, int cpu)
 {
-	struct perf_cpu_context *cpuctx;
+	/* XXX: Don't need this quirk anymore */
+	/*struct perf_cpu_context *cpuctx;
 
 	if (!pmu->pmu_cpu_context)
 		return;
 
 	cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
-	cpuctx->ctx.pmu = pmu;
+	cpuctx->ctx.pmu = pmu;*/
 }
 
 static int __init init_hw_perf_events(void)
@@ -2644,15 +2645,15 @@ static const struct attribute_group *x86
 	NULL,
 };
 
-static void x86_pmu_sched_task(struct perf_event_context *ctx, bool sched_in)
+static void x86_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
 {
-	static_call_cond(x86_pmu_sched_task)(ctx, sched_in);
+	static_call_cond(x86_pmu_sched_task)(pmu_ctx, sched_in);
 }
 
-static void x86_pmu_swap_task_ctx(struct perf_event_context *prev,
-				  struct perf_event_context *next)
+static void x86_pmu_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
+				  struct perf_event_pmu_context *next_epc)
 {
-	static_call_cond(x86_pmu_swap_task_ctx)(prev, next);
+	static_call_cond(x86_pmu_swap_task_ctx)(prev_epc, next_epc);
 }
 
 void perf_check_microcode(void)
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4545,17 +4545,17 @@ static void intel_pmu_cpu_dead(int cpu)
 		cpumask_clear_cpu(cpu, &hybrid_pmu(cpuc->pmu)->supported_cpus);
 }
 
-static void intel_pmu_sched_task(struct perf_event_context *ctx,
+static void intel_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx,
 				 bool sched_in)
 {
-	intel_pmu_pebs_sched_task(ctx, sched_in);
-	intel_pmu_lbr_sched_task(ctx, sched_in);
+	intel_pmu_pebs_sched_task(pmu_ctx, sched_in);
+	intel_pmu_lbr_sched_task(pmu_ctx, sched_in);
 }
 
-static void intel_pmu_swap_task_ctx(struct perf_event_context *prev,
-				    struct perf_event_context *next)
+static void intel_pmu_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
+				    struct perf_event_pmu_context *next_epc)
 {
-	intel_pmu_lbr_swap_task_ctx(prev, next);
+	intel_pmu_lbr_swap_task_ctx(prev_epc, next_epc);
 }
 
 static int intel_pmu_check_period(struct perf_event *event, u64 value)
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1005,7 +1005,7 @@ static inline bool pebs_needs_sched_cb(s
 	return cpuc->n_pebs && (cpuc->n_pebs == cpuc->n_large_pebs);
 }
 
-void intel_pmu_pebs_sched_task(struct perf_event_context *ctx, bool sched_in)
+void intel_pmu_pebs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 
@@ -1113,7 +1113,7 @@ static void
 pebs_update_state(bool needed_cb, struct cpu_hw_events *cpuc,
 		  struct perf_event *event, bool add)
 {
-	struct pmu *pmu = event->ctx->pmu;
+	struct pmu *pmu = event->pmu;
 	/*
 	 * Make sure we get updated with the first PEBS
 	 * event. It will trigger also during removal, but
--- a/arch/x86/events/intel/lbr.c
+++ b/arch/x86/events/intel/lbr.c
@@ -575,21 +575,21 @@ static void __intel_pmu_lbr_save(void *c
 	cpuc->last_log_id = ++task_context_opt(ctx)->log_id;
 }
 
-void intel_pmu_lbr_swap_task_ctx(struct perf_event_context *prev,
-				 struct perf_event_context *next)
+void intel_pmu_lbr_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
+				 struct perf_event_pmu_context *next_epc)
 {
 	void *prev_ctx_data, *next_ctx_data;
 
-	swap(prev->task_ctx_data, next->task_ctx_data);
+	swap(prev_epc->task_ctx_data, next_epc->task_ctx_data);
 
 	/*
-	 * Architecture specific synchronization makes sense in
-	 * case both prev->task_ctx_data and next->task_ctx_data
+	 * Architecture specific synchronization makes sense in case
+	 * both prev_epc->task_ctx_data and next_epc->task_ctx_data
 	 * pointers are allocated.
 	 */
 
-	prev_ctx_data = next->task_ctx_data;
-	next_ctx_data = prev->task_ctx_data;
+	prev_ctx_data = next_epc->task_ctx_data;
+	next_ctx_data = prev_epc->task_ctx_data;
 
 	if (!prev_ctx_data || !next_ctx_data)
 		return;
@@ -598,7 +598,7 @@ void intel_pmu_lbr_swap_task_ctx(struct
 	     task_context_opt(next_ctx_data)->lbr_callstack_users);
 }
 
-void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in)
+void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
 {
 	struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events);
 	void *task_ctx;
@@ -611,7 +611,7 @@ void intel_pmu_lbr_sched_task(struct per
 	 * the task was scheduled out, restore the stack. Otherwise flush
 	 * the LBR stack.
 	 */
-	task_ctx = ctx ? ctx->task_ctx_data : NULL;
+	task_ctx = pmu_ctx ? pmu_ctx->task_ctx_data : NULL;
 	if (task_ctx) {
 		if (sched_in)
 			__intel_pmu_lbr_restore(task_ctx);
@@ -647,8 +647,8 @@ void intel_pmu_lbr_add(struct perf_event
 
 	cpuc->br_sel = event->hw.branch_reg.reg;
 
-	if (branch_user_callstack(cpuc->br_sel) && event->ctx->task_ctx_data)
-		task_context_opt(event->ctx->task_ctx_data)->lbr_callstack_users++;
+	if (branch_user_callstack(cpuc->br_sel) && event->pmu_ctx->task_ctx_data)
+		task_context_opt(event->pmu_ctx->task_ctx_data)->lbr_callstack_users++;
 
 	/*
 	 * Request pmu::sched_task() callback, which will fire inside the
@@ -671,7 +671,7 @@ void intel_pmu_lbr_add(struct perf_event
 	 */
 	if (x86_pmu.intel_cap.pebs_baseline && event->attr.precise_ip > 0)
 		cpuc->lbr_pebs_users++;
-	perf_sched_cb_inc(event->ctx->pmu);
+	perf_sched_cb_inc(event->pmu);
 	if (!cpuc->lbr_users++ && !event->total_time_running)
 		intel_pmu_lbr_reset();
 }
@@ -724,8 +724,8 @@ void intel_pmu_lbr_del(struct perf_event
 		return;
 
 	if (branch_user_callstack(cpuc->br_sel) &&
-	    event->ctx->task_ctx_data)
-		task_context_opt(event->ctx->task_ctx_data)->lbr_callstack_users--;
+	    event->pmu_ctx->task_ctx_data)
+		task_context_opt(event->pmu_ctx->task_ctx_data)->lbr_callstack_users--;
 
 	if (event->hw.flags & PERF_X86_EVENT_LBR_SELECT)
 		cpuc->lbr_select = 0;
@@ -735,7 +735,7 @@ void intel_pmu_lbr_del(struct perf_event
 	cpuc->lbr_users--;
 	WARN_ON_ONCE(cpuc->lbr_users < 0);
 	WARN_ON_ONCE(cpuc->lbr_pebs_users < 0);
-	perf_sched_cb_dec(event->ctx->pmu);
+	perf_sched_cb_dec(event->pmu);
 }
 
 static inline bool vlbr_exclude_host(void)
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -798,7 +798,7 @@ struct x86_pmu {
 	void		(*cpu_dead)(int cpu);
 
 	void		(*check_microcode)(void);
-	void		(*sched_task)(struct perf_event_context *ctx,
+	void		(*sched_task)(struct perf_event_pmu_context *pmu_ctx,
 				      bool sched_in);
 
 	/*
@@ -880,12 +880,12 @@ struct x86_pmu {
 	int		(*set_topdown_event_period)(struct perf_event *event);
 
 	/*
-	 * perf task context (i.e. struct perf_event_context::task_ctx_data)
+	 * perf task context (i.e. struct perf_event_pmu_context::task_ctx_data)
 	 * switch helper to bridge calls from perf/core to perf/x86.
 	 * See struct pmu::swap_task_ctx() usage for examples;
 	 */
-	void		(*swap_task_ctx)(struct perf_event_context *prev,
-					 struct perf_event_context *next);
+	void		(*swap_task_ctx)(struct perf_event_pmu_context *prev_epc,
+					 struct perf_event_pmu_context *next_epc);
 
 	/*
 	 * AMD bits
@@ -1253,7 +1253,7 @@ static inline void amd_pmu_brs_del(struc
 	perf_sched_cb_dec(event->ctx->pmu);
 }
 
-void amd_pmu_brs_sched_task(struct perf_event_context *ctx, bool sched_in);
+void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in);
 #else
 static inline int amd_brs_init(void)
 {
@@ -1278,7 +1278,7 @@ static inline void amd_pmu_brs_del(struc
 {
 }
 
-static inline void amd_pmu_brs_sched_task(struct perf_event_context *ctx, bool sched_in)
+static inline void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in)
 {
 }
 
@@ -1436,7 +1436,7 @@ void intel_pmu_pebs_enable_all(void);
 
 void intel_pmu_pebs_disable_all(void);
 
-void intel_pmu_pebs_sched_task(struct perf_event_context *ctx, bool sched_in);
+void intel_pmu_pebs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in);
 
 void intel_pmu_auto_reload_read(struct perf_event *event);
 
@@ -1444,10 +1444,10 @@ void intel_pmu_store_pebs_lbrs(struct lb
 
 void intel_ds_init(void);
 
-void intel_pmu_lbr_swap_task_ctx(struct perf_event_context *prev,
-				 struct perf_event_context *next);
+void intel_pmu_lbr_swap_task_ctx(struct perf_event_pmu_context *prev_epc,
+				 struct perf_event_pmu_context *next_epc);
 
-void intel_pmu_lbr_sched_task(struct perf_event_context *ctx, bool sched_in);
+void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in);
 
 u64 lbr_from_signext_quirk_wr(u64 val);
 
--- a/include/linux/perf_event.h
+++ b/include/linux/perf_event.h
@@ -262,6 +262,7 @@ struct hw_perf_event {
 };
 
 struct perf_event;
+struct perf_event_pmu_context;
 
 /*
  * Common implementation detail of pmu::{start,commit,cancel}_txn
@@ -304,7 +305,7 @@ struct pmu {
 	int				capabilities;
 
 	int __percpu			*pmu_disable_count;
-	struct perf_cpu_context __percpu *pmu_cpu_context;
+	struct perf_cpu_pmu_context __percpu *cpu_pmu_context;
 	atomic_t			exclusive_cnt; /* < 0: cpu; > 0: tsk */
 	int				task_ctx_nr;
 	int				hrtimer_interval_ms;
@@ -439,7 +440,7 @@ struct pmu {
 	/*
 	 * context-switches callback
 	 */
-	void (*sched_task)		(struct perf_event_context *ctx,
+	void (*sched_task)		(struct perf_event_pmu_context *pmu_ctx,
 					bool sched_in);
 
 	/*
@@ -453,8 +454,8 @@ struct pmu {
 	 * implementation and Perf core context switch handling callbacks for usage
 	 * examples.
 	 */
-	void (*swap_task_ctx)		(struct perf_event_context *prev,
-					 struct perf_event_context *next);
+	void (*swap_task_ctx)		(struct perf_event_pmu_context *prev_epc,
+					 struct perf_event_pmu_context *next_epc);
 					/* optional */
 
 	/*
@@ -675,6 +676,11 @@ struct perf_event {
 	int				group_caps;
 
 	struct perf_event		*group_leader;
+	/*
+	 * event->pmu will always point to pmu in which this event belongs.
+	 * Unlike event->pmu_ctx->pmu which points to other pmu when group of
+	 * different events are created.
+	 */
 	struct pmu			*pmu;
 	void				*pmu_private;
 
@@ -700,6 +706,12 @@ struct perf_event {
 	struct hw_perf_event		hw;
 
 	struct perf_event_context	*ctx;
+	/*
+	 * event->pmu_ctx points to perf_event_pmu_context in which the event
+	 * is added. This pmu_ctx can be of other pmu for sw event when such
+	 * sw event is added to a non-sw event group.
+	 */
+	struct perf_event_pmu_context	*pmu_ctx;
 	atomic_long_t			refcount;
 
 	/*
@@ -787,19 +799,60 @@ struct perf_event {
 #endif /* CONFIG_PERF_EVENTS */
 };
 
+/*
+ *           ,------------------------[1:n]---------------------.
+ *           V                                                  V
+ * perf_event_context <-[1:n]-> perf_event_pmu_context <--- perf_event
+ *           ^                      ^     |                     |
+ *           `--------[1:n]---------'     `-[n:1]-> pmu <-[1:n]-'
+ *
+ *
+ * XXX destroy epc when empty
+ *   refcount, !rcu
+ *
+ * XXX epc locking
+ *
+ *   event->pmu_ctx            ctx->mutex && inactive
+ *   ctx->pmu_ctx_list         ctx->mutex && ctx->lock
+ *
+ */
+struct perf_event_pmu_context {
+	struct pmu			*pmu;
+	struct perf_event_context       *ctx;
+
+	struct list_head		pmu_ctx_entry;
+
+	struct list_head		pinned_active;
+	struct list_head		flexible_active;
+
+	/* Used to avoid freeing per-cpu perf_event_pmu_context */
+	unsigned int			embedded : 1;
+
+	unsigned int			nr_events;
+	unsigned int			nr_active;
+
+	atomic_t			refcount; /* event <-> epc */
+
+	void				*task_ctx_data; /* pmu specific data */
+	/*
+	 * Set when nr_events != nr_active, except tolerant to events not
+	 * necessary to be active due to scheduling constraints, such as cgroups.
+	 */
+	int				rotate_necessary;
+};
 
 struct perf_event_groups {
 	struct rb_root	tree;
 	u64		index;
 };
 
+
 /**
  * struct perf_event_context - event context structure
  *
  * Used as a container for task events and CPU events as well:
  */
 struct perf_event_context {
-	struct pmu			*pmu;
 	/*
 	 * Protect the states of the events in the list,
 	 * nr_active, and the list:
@@ -812,26 +865,21 @@ struct perf_event_context {
 	 */
 	struct mutex			mutex;
 
-	struct list_head		active_ctx_list;
+	struct list_head		pmu_ctx_list;
 	struct perf_event_groups	pinned_groups;
 	struct perf_event_groups	flexible_groups;
 	struct list_head		event_list;
 
-	struct list_head		pinned_active;
-	struct list_head		flexible_active;
-
 	int				nr_events;
 	int				nr_active;
 	int				nr_user;
 	int				is_active;
+
+	int				nr_task_data;
 	int				nr_stat;
 	int				nr_freq;
 	int				rotate_disable;
-	/*
-	 * Set when nr_events != nr_active, except tolerant to events not
-	 * necessary to be active due to scheduling constraints, such as cgroups.
-	 */
-	int				rotate_necessary;
+
 	refcount_t			refcount;
 	struct task_struct		*task;
 
@@ -853,7 +901,6 @@ struct perf_event_context {
 #ifdef CONFIG_CGROUP_PERF
 	int				nr_cgroups;	 /* cgroup evts */
 #endif
-	void				*task_ctx_data; /* pmu specific data */
 	struct rcu_head			rcu_head;
 };
 
@@ -863,12 +910,13 @@ struct perf_event_context {
  */
 #define PERF_NR_CONTEXTS	4
 
-/**
- * struct perf_cpu_context - per cpu event context structure
- */
-struct perf_cpu_context {
-	struct perf_event_context	ctx;
-	struct perf_event_context	*task_ctx;
+struct perf_cpu_pmu_context {
+	struct perf_event_pmu_context	epc;
+	struct perf_event_pmu_context	*task_epc;
+
+	struct list_head		sched_cb_entry;
+	int				sched_cb_usage;
+
 	int				active_oncpu;
 	int				exclusive;
 
@@ -876,16 +924,21 @@ struct perf_cpu_context {
 	struct hrtimer			hrtimer;
 	ktime_t				hrtimer_interval;
 	unsigned int			hrtimer_active;
+};
+
+/**
+ * struct perf_event_cpu_context - per cpu event context structure
+ */
+struct perf_cpu_context {
+	struct perf_event_context	ctx;
+	struct perf_event_context	*task_ctx;
+	int				online;
 
 #ifdef CONFIG_CGROUP_PERF
 	struct perf_cgroup		*cgrp;
 	struct list_head		cgrp_cpuctx_entry;
 #endif
 
-	struct list_head		sched_cb_entry;
-	int				sched_cb_usage;
-
-	int				online;
 	/*
 	 * Per-CPU storage for iterators used in visit_groups_merge. The default
 	 * storage is of size 2 to hold the CPU and any CPU event iterators.
@@ -1151,7 +1204,7 @@ static inline int is_software_event(stru
  */
 static inline int in_software_context(struct perf_event *event)
 {
-	return event->ctx->pmu->task_ctx_nr == perf_sw_context;
+	return event->pmu_ctx->pmu->task_ctx_nr == perf_sw_context;
 }
 
 static inline int is_exclusive_pmu(struct pmu *pmu)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1226,7 +1226,7 @@ struct task_struct {
 	unsigned int			futex_state;
 #endif
 #ifdef CONFIG_PERF_EVENTS
-	struct perf_event_context	*perf_event_ctxp[perf_nr_task_contexts];
+	struct perf_event_context	*perf_event_ctxp;
 	struct mutex			perf_event_mutex;
 	struct list_head		perf_event_list;
 #endif
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -154,12 +154,6 @@ static int cpu_function_call(int cpu, re
 	return data.ret;
 }
 
-static inline struct perf_cpu_context *
-__get_cpu_context(struct perf_event_context *ctx)
-{
-	return this_cpu_ptr(ctx->pmu->pmu_cpu_context);
-}
-
 static void perf_ctx_lock(struct perf_cpu_context *cpuctx,
 			  struct perf_event_context *ctx)
 {
@@ -183,6 +177,8 @@ static bool is_kernel_event(struct perf_
 	return READ_ONCE(event->owner) == TASK_TOMBSTONE;
 }
 
+static DEFINE_PER_CPU(struct perf_cpu_context, cpu_context);
+
 /*
  * On task ctx scheduling...
  *
@@ -216,7 +212,7 @@ static int event_function(void *info)
 	struct event_function_struct *efs = info;
 	struct perf_event *event = efs->event;
 	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	struct perf_event_context *task_ctx = cpuctx->task_ctx;
 	int ret = 0;
 
@@ -313,7 +309,7 @@ static void event_function_call(struct p
 static void event_function_local(struct perf_event *event, event_f func, void *data)
 {
 	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	struct task_struct *task = READ_ONCE(ctx->task);
 	struct perf_event_context *task_ctx = NULL;
 
@@ -387,7 +383,6 @@ static DEFINE_MUTEX(perf_sched_mutex);
 static atomic_t perf_sched_count;
 
 static DEFINE_PER_CPU(atomic_t, perf_cgroup_events);
-static DEFINE_PER_CPU(int, perf_sched_cb_usages);
 static DEFINE_PER_CPU(struct pmu_event_list, pmu_sb_events);
 
 static atomic_t nr_mmap_events __read_mostly;
@@ -447,7 +442,7 @@ static void update_perf_cpu_limits(void)
 	WRITE_ONCE(perf_sample_allowed_ns, tmp);
 }
 
-static bool perf_rotate_context(struct perf_cpu_context *cpuctx);
+static bool perf_rotate_context(struct perf_cpu_pmu_context *cpc);
 
 int perf_proc_update_handler(struct ctl_table *table, int write,
 		void *buffer, size_t *lenp, loff_t *ppos)
@@ -570,12 +565,6 @@ void perf_sample_event_took(u64 sample_l
 
 static atomic64_t perf_event_id;
 
-static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
-			      enum event_type_t event_type);
-
-static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
-			     enum event_type_t event_type);
-
 static void update_context_time(struct perf_event_context *ctx);
 static u64 perf_event_time(struct perf_event *event);
 
@@ -690,13 +679,31 @@ do {									\
 	___p;								\
 })
 
+static void perf_ctx_disable(struct perf_event_context *ctx)
+{
+	struct perf_event_pmu_context *pmu_ctx;
+
+	list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry)
+		perf_pmu_disable(pmu_ctx->pmu);
+}
+
+static void perf_ctx_enable(struct perf_event_context *ctx)
+{
+	struct perf_event_pmu_context *pmu_ctx;
+
+	list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry)
+		perf_pmu_enable(pmu_ctx->pmu);
+}
+
+static void ctx_sched_out(struct perf_event_context *ctx, enum event_type_t event_type);
+static void ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type);
+
 #ifdef CONFIG_CGROUP_PERF
 
 static inline bool
 perf_cgroup_match(struct perf_event *event)
 {
-	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 
 	/* @event doesn't care about cgroup */
 	if (!event->cgrp)
@@ -822,6 +829,7 @@ perf_cgroup_set_timestamp(struct perf_cp
 	}
 }
 
+/* XXX: No need of list now. Convert it to per-cpu variable */
 static DEFINE_PER_CPU(struct list_head, cgrp_cpuctx_list);
 
 /*
@@ -849,9 +857,9 @@ static void perf_cgroup_switch(struct ta
 			continue;
 
 		perf_ctx_lock(cpuctx, cpuctx->task_ctx);
-		perf_pmu_disable(cpuctx->ctx.pmu);
+		perf_ctx_disable(&cpuctx->ctx);
 
-		cpu_ctx_sched_out(cpuctx, EVENT_ALL);
+		ctx_sched_out(&cpuctx->ctx, EVENT_ALL);
 		/*
 		 * must not be done before ctxswout due
 		 * to update_cgrp_time_from_cpuctx() in
@@ -863,9 +871,9 @@ static void perf_cgroup_switch(struct ta
 		 * perf_cgroup_set_timestamp() in ctx_sched_in()
 		 * to not have to pass task around
 		 */
-		cpu_ctx_sched_in(cpuctx, EVENT_ALL);
+		ctx_sched_in(&cpuctx->ctx, EVENT_ALL);
 
-		perf_pmu_enable(cpuctx->ctx.pmu);
+		perf_ctx_enable(&cpuctx->ctx);
 		perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
 	}
 
@@ -887,7 +895,7 @@ static int perf_cgroup_ensure_storage(st
 		heap_size++;
 
 	for_each_possible_cpu(cpu) {
-		cpuctx = per_cpu_ptr(event->pmu->pmu_cpu_context, cpu);
+		cpuctx = this_cpu_ptr(&cpu_context);
 		if (heap_size <= cpuctx->heap_size)
 			continue;
 
@@ -1068,34 +1076,30 @@ static void perf_cgroup_switch(struct ta
  */
 static enum hrtimer_restart perf_mux_hrtimer_handler(struct hrtimer *hr)
 {
-	struct perf_cpu_context *cpuctx;
+	struct perf_cpu_pmu_context *cpc;
 	bool rotations;
 
 	lockdep_assert_irqs_disabled();
 
-	cpuctx = container_of(hr, struct perf_cpu_context, hrtimer);
-	rotations = perf_rotate_context(cpuctx);
+	cpc = container_of(hr, struct perf_cpu_pmu_context, hrtimer);
+	rotations = perf_rotate_context(cpc);
 
-	raw_spin_lock(&cpuctx->hrtimer_lock);
+	raw_spin_lock(&cpc->hrtimer_lock);
 	if (rotations)
-		hrtimer_forward_now(hr, cpuctx->hrtimer_interval);
+		hrtimer_forward_now(hr, cpc->hrtimer_interval);
 	else
-		cpuctx->hrtimer_active = 0;
-	raw_spin_unlock(&cpuctx->hrtimer_lock);
+		cpc->hrtimer_active = 0;
+	raw_spin_unlock(&cpc->hrtimer_lock);
 
 	return rotations ? HRTIMER_RESTART : HRTIMER_NORESTART;
 }
 
-static void __perf_mux_hrtimer_init(struct perf_cpu_context *cpuctx, int cpu)
+static void __perf_mux_hrtimer_init(struct perf_cpu_pmu_context *cpc, int cpu)
 {
-	struct hrtimer *timer = &cpuctx->hrtimer;
-	struct pmu *pmu = cpuctx->ctx.pmu;
+	struct hrtimer *timer = &cpc->hrtimer;
+	struct pmu *pmu = cpc->epc.pmu;
 	u64 interval;
 
-	/* no multiplexing needed for SW PMU */
-	if (pmu->task_ctx_nr == perf_sw_context)
-		return;
-
 	/*
 	 * check default is sane, if not set then force to
 	 * default interval (1/tick)
@@ -1104,30 +1108,25 @@ static void __perf_mux_hrtimer_init(stru
 	if (interval < 1)
 		interval = pmu->hrtimer_interval_ms = PERF_CPU_HRTIMER;
 
-	cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * interval);
+	cpc->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * interval);
 
-	raw_spin_lock_init(&cpuctx->hrtimer_lock);
+	raw_spin_lock_init(&cpc->hrtimer_lock);
 	hrtimer_init(timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED_HARD);
 	timer->function = perf_mux_hrtimer_handler;
 }
 
-static int perf_mux_hrtimer_restart(struct perf_cpu_context *cpuctx)
+static int perf_mux_hrtimer_restart(struct perf_cpu_pmu_context *cpc)
 {
-	struct hrtimer *timer = &cpuctx->hrtimer;
-	struct pmu *pmu = cpuctx->ctx.pmu;
+	struct hrtimer *timer = &cpc->hrtimer;
 	unsigned long flags;
 
-	/* not for SW PMU */
-	if (pmu->task_ctx_nr == perf_sw_context)
-		return 0;
-
-	raw_spin_lock_irqsave(&cpuctx->hrtimer_lock, flags);
-	if (!cpuctx->hrtimer_active) {
-		cpuctx->hrtimer_active = 1;
-		hrtimer_forward_now(timer, cpuctx->hrtimer_interval);
+	raw_spin_lock_irqsave(&cpc->hrtimer_lock, flags);
+	if (!cpc->hrtimer_active) {
+		cpc->hrtimer_active = 1;
+		hrtimer_forward_now(timer, cpc->hrtimer_interval);
 		hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD);
 	}
-	raw_spin_unlock_irqrestore(&cpuctx->hrtimer_lock, flags);
+	raw_spin_unlock_irqrestore(&cpc->hrtimer_lock, flags);
 
 	return 0;
 }
@@ -1146,32 +1145,9 @@ void perf_pmu_enable(struct pmu *pmu)
 		pmu->pmu_enable(pmu);
 }
 
-static DEFINE_PER_CPU(struct list_head, active_ctx_list);
-
-/*
- * perf_event_ctx_activate(), perf_event_ctx_deactivate(), and
- * perf_event_task_tick() are fully serialized because they're strictly cpu
- * affine and perf_event_ctx{activate,deactivate} are called with IRQs
- * disabled, while perf_event_task_tick is called from IRQ context.
- */
-static void perf_event_ctx_activate(struct perf_event_context *ctx)
-{
-	struct list_head *head = this_cpu_ptr(&active_ctx_list);
-
-	lockdep_assert_irqs_disabled();
-
-	WARN_ON(!list_empty(&ctx->active_ctx_list));
-
-	list_add(&ctx->active_ctx_list, head);
-}
-
-static void perf_event_ctx_deactivate(struct perf_event_context *ctx)
+static void perf_assert_pmu_disabled(struct pmu *pmu)
 {
-	lockdep_assert_irqs_disabled();
-
-	WARN_ON(list_empty(&ctx->active_ctx_list));
-
-	list_del_init(&ctx->active_ctx_list);
+	WARN_ON_ONCE(*this_cpu_ptr(pmu->pmu_disable_count) == 0);
 }
 
 static void get_ctx(struct perf_event_context *ctx)
@@ -1198,7 +1174,6 @@ static void free_ctx(struct rcu_head *he
 	struct perf_event_context *ctx;
 
 	ctx = container_of(head, struct perf_event_context, rcu_head);
-	free_task_ctx_data(ctx->pmu, ctx->task_ctx_data);
 	kfree(ctx);
 }
 
@@ -1383,7 +1358,7 @@ static u64 primary_event_id(struct perf_
  * the context could get moved to another task.
  */
 static struct perf_event_context *
-perf_lock_task_context(struct task_struct *task, int ctxn, unsigned long *flags)
+perf_lock_task_context(struct task_struct *task, unsigned long *flags)
 {
 	struct perf_event_context *ctx;
 
@@ -1399,7 +1374,7 @@ perf_lock_task_context(struct task_struc
 	 */
 	local_irq_save(*flags);
 	rcu_read_lock();
-	ctx = rcu_dereference(task->perf_event_ctxp[ctxn]);
+	ctx = rcu_dereference(task->perf_event_ctxp);
 	if (ctx) {
 		/*
 		 * If this context is a clone of another, it might
@@ -1412,7 +1387,7 @@ perf_lock_task_context(struct task_struc
 		 * can't get swapped on us any more.
 		 */
 		raw_spin_lock(&ctx->lock);
-		if (ctx != rcu_dereference(task->perf_event_ctxp[ctxn])) {
+		if (ctx != rcu_dereference(task->perf_event_ctxp)) {
 			raw_spin_unlock(&ctx->lock);
 			rcu_read_unlock();
 			local_irq_restore(*flags);
@@ -1439,12 +1414,12 @@ perf_lock_task_context(struct task_struc
  * reference count so that the context can't get freed.
  */
 static struct perf_event_context *
-perf_pin_task_context(struct task_struct *task, int ctxn)
+perf_pin_task_context(struct task_struct *task)
 {
 	struct perf_event_context *ctx;
 	unsigned long flags;
 
-	ctx = perf_lock_task_context(task, ctxn, &flags);
+	ctx = perf_lock_task_context(task, &flags);
 	if (ctx) {
 		++ctx->pin_count;
 		raw_spin_unlock_irqrestore(&ctx->lock, flags);
@@ -1590,14 +1565,22 @@ static inline struct cgroup *event_cgrou
  * which provides ordering when rotating groups for the same CPU.
  */
 static __always_inline int
-perf_event_groups_cmp(const int left_cpu, const struct cgroup *left_cgroup,
-		      const u64 left_group_index, const struct perf_event *right)
+perf_event_groups_cmp(const int left_cpu, const struct pmu *left_pmu,
+		      const struct cgroup *left_cgroup, const u64 left_group_index,
+		      const struct perf_event *right)
 {
 	if (left_cpu < right->cpu)
 		return -1;
 	if (left_cpu > right->cpu)
 		return 1;
 
+	if (left_pmu) {
+		if (left_pmu < right->pmu_ctx->pmu)
+			return -1;
+		if (left_pmu > right->pmu_ctx->pmu)
+			return 1;
+	}
+
 #ifdef CONFIG_CGROUP_PERF
 	{
 		const struct cgroup *right_cgroup = event_cgroup(right);
@@ -1640,12 +1623,13 @@ perf_event_groups_cmp(const int left_cpu
 static inline bool __group_less(struct rb_node *a, const struct rb_node *b)
 {
 	struct perf_event *e = __node_2_pe(a);
-	return perf_event_groups_cmp(e->cpu, event_cgroup(e), e->group_index,
-				     __node_2_pe(b)) < 0;
+	return perf_event_groups_cmp(e->cpu, e->pmu_ctx->pmu, event_cgroup(e),
+				     e->group_index, __node_2_pe(b)) < 0;
 }
 
 struct __group_key {
 	int cpu;
+	struct pmu *pmu;
 	struct cgroup *cgroup;
 };
 
@@ -1654,14 +1638,25 @@ static inline int __group_cmp(const void
 	const struct __group_key *a = key;
 	const struct perf_event *b = __node_2_pe(node);
 
-	/* partial/subtree match: @cpu, @cgroup; ignore: @group_index */
-	return perf_event_groups_cmp(a->cpu, a->cgroup, b->group_index, b);
+	/* partial/subtree match: @cpu, @pmu, @cgroup; ignore: @group_index */
+	return perf_event_groups_cmp(a->cpu, a->pmu, a->cgroup, b->group_index, b);
+}
+
+static inline int
+__group_cmp_ignore_cgroup(const void *key, const struct rb_node *node)
+{
+	const struct __group_key *a = key;
+	const struct perf_event *b = __node_2_pe(node);
+
+	/* partial/subtree match: @cpu, @pmu, ignore: @cgroup, @group_index */
+	return perf_event_groups_cmp(a->cpu, a->pmu, event_cgroup(b),
+				     b->group_index, b);
 }
 
 /*
- * Insert @event into @groups' tree; using {@event->cpu, ++@groups->index} for
- * key (see perf_event_groups_less). This places it last inside the CPU
- * subtree.
+ * Insert @event into @groups' tree; using
+ *   {@event->cpu, @event->pmu_ctx->pmu, event_cgroup(@event), ++@groups->index}
+ * as key. This places it last inside the {cpu,pmu,cgroup} subtree.
  */
 static void
 perf_event_groups_insert(struct perf_event_groups *groups,
@@ -1711,14 +1706,15 @@ del_event_from_groups(struct perf_event
 }
 
 /*
- * Get the leftmost event in the cpu/cgroup subtree.
+ * Get the leftmost event in the {cpu,pmu,cgroup} subtree.
  */
 static struct perf_event *
 perf_event_groups_first(struct perf_event_groups *groups, int cpu,
-			struct cgroup *cgrp)
+			struct pmu *pmu, struct cgroup *cgrp)
 {
 	struct __group_key key = {
 		.cpu = cpu,
+		.pmu = pmu,
 		.cgroup = cgrp,
 	};
 	struct rb_node *node;
@@ -1730,14 +1726,12 @@ perf_event_groups_first(struct perf_even
 	return NULL;
 }
 
-/*
- * Like rb_entry_next_safe() for the @cpu subtree.
- */
 static struct perf_event *
-perf_event_groups_next(struct perf_event *event)
+perf_event_groups_next(struct perf_event *event, struct pmu *pmu)
 {
 	struct __group_key key = {
 		.cpu = event->cpu,
+		.pmu = pmu,
 		.cgroup = event_cgroup(event),
 	};
 	struct rb_node *next;
@@ -1793,6 +1787,7 @@ list_add_event(struct perf_event *event,
 		perf_cgroup_event_enable(event, ctx);
 
 	ctx->generation++;
+	event->pmu_ctx->nr_events++;
 }
 
 /*
@@ -2000,6 +1995,7 @@ list_del_event(struct perf_event *event,
 	}
 
 	ctx->generation++;
+	event->pmu_ctx->nr_events--;
 }
 
 static int
@@ -2016,13 +2012,11 @@ perf_aux_output_match(struct perf_event
 
 static void put_event(struct perf_event *event);
 static void event_sched_out(struct perf_event *event,
-			    struct perf_cpu_context *cpuctx,
 			    struct perf_event_context *ctx);
 
 static void perf_put_aux_event(struct perf_event *event)
 {
 	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
 	struct perf_event *iter;
 
 	/*
@@ -2051,7 +2045,7 @@ static void perf_put_aux_event(struct pe
 		 * state so that we don't try to schedule it again. Note
 		 * that perf_event_enable() will clear the ERROR status.
 		 */
-		event_sched_out(iter, cpuctx, ctx);
+		event_sched_out(iter, ctx);
 		perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
 	}
 }
@@ -2102,8 +2096,8 @@ static int perf_get_aux_event(struct per
 
 static inline struct list_head *get_event_list(struct perf_event *event)
 {
-	struct perf_event_context *ctx = event->ctx;
-	return event->attr.pinned ? &ctx->pinned_active : &ctx->flexible_active;
+	return event->attr.pinned ? &event->pmu_ctx->pinned_active :
+				    &event->pmu_ctx->flexible_active;
 }
 
 /*
@@ -2114,10 +2108,7 @@ static inline struct list_head *get_even
  */
 static inline void perf_remove_sibling_event(struct perf_event *event)
 {
-	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
-
-	event_sched_out(event, cpuctx, ctx);
+	event_sched_out(event, event->ctx);
 	perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
 }
 
@@ -2241,12 +2232,14 @@ event_filter_match(struct perf_event *ev
 }
 
 static void
-event_sched_out(struct perf_event *event,
-		  struct perf_cpu_context *cpuctx,
-		  struct perf_event_context *ctx)
+event_sched_out(struct perf_event *event, struct perf_event_context *ctx)
 {
+	struct perf_event_pmu_context *epc = event->pmu_ctx;
+	struct perf_cpu_pmu_context *cpc = this_cpu_ptr(epc->pmu->cpu_pmu_context);
 	enum perf_event_state state = PERF_EVENT_STATE_INACTIVE;
 
+	// XXX cpc serialization, probably per-cpu IRQ disabled
+
 	WARN_ON_ONCE(event->ctx != ctx);
 	lockdep_assert_held(&ctx->lock);
 
@@ -2273,38 +2266,34 @@ event_sched_out(struct perf_event *event
 	perf_event_set_state(event, state);
 
 	if (!is_software_event(event))
-		cpuctx->active_oncpu--;
-	if (!--ctx->nr_active)
-		perf_event_ctx_deactivate(ctx);
+		cpc->active_oncpu--;
+	ctx->nr_active--;
+	event->pmu_ctx->nr_active--;
 	if (event->attr.freq && event->attr.sample_freq)
 		ctx->nr_freq--;
-	if (event->attr.exclusive || !cpuctx->active_oncpu)
-		cpuctx->exclusive = 0;
+	if (event->attr.exclusive || !cpc->active_oncpu)
+		cpc->exclusive = 0;
 
 	perf_pmu_enable(event->pmu);
 }
 
 static void
-group_sched_out(struct perf_event *group_event,
-		struct perf_cpu_context *cpuctx,
-		struct perf_event_context *ctx)
+group_sched_out(struct perf_event *group_event, struct perf_event_context *ctx)
 {
 	struct perf_event *event;
 
 	if (group_event->state != PERF_EVENT_STATE_ACTIVE)
 		return;
 
-	perf_pmu_disable(ctx->pmu);
+	perf_assert_pmu_disabled(group_event->pmu_ctx->pmu);
 
-	event_sched_out(group_event, cpuctx, ctx);
+	event_sched_out(group_event, ctx);
 
 	/*
 	 * Schedule out siblings (if any):
 	 */
 	for_each_sibling_event(event, group_event)
-		event_sched_out(event, cpuctx, ctx);
-
-	perf_pmu_enable(ctx->pmu);
+		event_sched_out(event, ctx);
 }
 
 #define DETACH_GROUP	0x01UL
@@ -2329,19 +2318,21 @@ __perf_remove_from_context(struct perf_e
 		update_cgrp_time_from_cpuctx(cpuctx, false);
 	}
 
-	event_sched_out(event, cpuctx, ctx);
+	event_sched_out(event, ctx);
 	if (flags & DETACH_GROUP)
 		perf_group_detach(event);
 	if (flags & DETACH_CHILD)
 		perf_child_detach(event);
 	list_del_event(event, ctx);
 
+	if (!event->pmu_ctx->nr_events)
+		event->pmu_ctx->rotate_necessary = 0;
+
 	if (!ctx->nr_events && ctx->is_active) {
 		if (ctx == &cpuctx->ctx)
 			update_cgrp_time_from_cpuctx(cpuctx, true);
 
 		ctx->is_active = 0;
-		ctx->rotate_necessary = 0;
 		if (ctx->task) {
 			WARN_ON_ONCE(cpuctx->task_ctx != ctx);
 			cpuctx->task_ctx = NULL;
@@ -2376,7 +2367,7 @@ static void perf_remove_from_context(str
 	 * cgrp_cpuctx_list.
 	 */
 	if (!ctx->is_active && !is_cgroup_event(event)) {
-		__perf_remove_from_context(event, __get_cpu_context(ctx),
+		__perf_remove_from_context(event, this_cpu_ptr(&cpu_context),
 					   ctx, (void *)flags);
 		raw_spin_unlock_irq(&ctx->lock);
 		return;
@@ -2402,13 +2393,17 @@ static void __perf_event_disable(struct
 		update_cgrp_time_from_event(event);
 	}
 
+	perf_pmu_disable(event->pmu_ctx->pmu);
+
 	if (event == event->group_leader)
-		group_sched_out(event, cpuctx, ctx);
+		group_sched_out(event, ctx);
 	else
-		event_sched_out(event, cpuctx, ctx);
+		event_sched_out(event, ctx);
 
 	perf_event_set_state(event, PERF_EVENT_STATE_OFF);
 	perf_cgroup_event_disable(event, ctx);
+
+	perf_pmu_enable(event->pmu_ctx->pmu);
 }
 
 /*
@@ -2471,10 +2466,10 @@ static void perf_log_throttle(struct per
 static void perf_log_itrace_start(struct perf_event *event);
 
 static int
-event_sched_in(struct perf_event *event,
-		 struct perf_cpu_context *cpuctx,
-		 struct perf_event_context *ctx)
+event_sched_in(struct perf_event *event, struct perf_event_context *ctx)
 {
+	struct perf_event_pmu_context *epc = event->pmu_ctx;
+	struct perf_cpu_pmu_context *cpc = this_cpu_ptr(epc->pmu->cpu_pmu_context);
 	int ret = 0;
 
 	WARN_ON_ONCE(event->ctx != ctx);
@@ -2515,14 +2510,14 @@ event_sched_in(struct perf_event *event,
 	}
 
 	if (!is_software_event(event))
-		cpuctx->active_oncpu++;
-	if (!ctx->nr_active++)
-		perf_event_ctx_activate(ctx);
+		cpc->active_oncpu++;
+	ctx->nr_active++;
+	event->pmu_ctx->nr_active++;
 	if (event->attr.freq && event->attr.sample_freq)
 		ctx->nr_freq++;
 
 	if (event->attr.exclusive)
-		cpuctx->exclusive = 1;
+		cpc->exclusive = 1;
 
 out:
 	perf_pmu_enable(event->pmu);
@@ -2531,26 +2526,24 @@ event_sched_in(struct perf_event *event,
 }
 
 static int
-group_sched_in(struct perf_event *group_event,
-	       struct perf_cpu_context *cpuctx,
-	       struct perf_event_context *ctx)
+group_sched_in(struct perf_event *group_event, struct perf_event_context *ctx)
 {
 	struct perf_event *event, *partial_group = NULL;
-	struct pmu *pmu = ctx->pmu;
+	struct pmu *pmu = group_event->pmu_ctx->pmu;
 
 	if (group_event->state == PERF_EVENT_STATE_OFF)
 		return 0;
 
 	pmu->start_txn(pmu, PERF_PMU_TXN_ADD);
 
-	if (event_sched_in(group_event, cpuctx, ctx))
+	if (event_sched_in(group_event, ctx))
 		goto error;
 
 	/*
 	 * Schedule in siblings as one group (if any):
 	 */
 	for_each_sibling_event(event, group_event) {
-		if (event_sched_in(event, cpuctx, ctx)) {
+		if (event_sched_in(event, ctx)) {
 			partial_group = event;
 			goto group_error;
 		}
@@ -2569,9 +2562,9 @@ group_sched_in(struct perf_event *group_
 		if (event == partial_group)
 			break;
 
-		event_sched_out(event, cpuctx, ctx);
+		event_sched_out(event, ctx);
 	}
-	event_sched_out(group_event, cpuctx, ctx);
+	event_sched_out(group_event, ctx);
 
 error:
 	pmu->cancel_txn(pmu);
@@ -2581,10 +2574,11 @@ group_sched_in(struct perf_event *group_
 /*
  * Work out whether we can put this event group on the CPU now.
  */
-static int group_can_go_on(struct perf_event *event,
-			   struct perf_cpu_context *cpuctx,
-			   int can_add_hw)
+static int group_can_go_on(struct perf_event *event, int can_add_hw)
 {
+	struct perf_event_pmu_context *epc = event->pmu_ctx;
+	struct perf_cpu_pmu_context *cpc = this_cpu_ptr(epc->pmu->cpu_pmu_context);
+
 	/*
 	 * Groups consisting entirely of software events can always go on.
 	 */
@@ -2594,7 +2588,7 @@ static int group_can_go_on(struct perf_e
 	 * If an exclusive group is already on, no other hardware
 	 * events can go on.
 	 */
-	if (cpuctx->exclusive)
+	if (cpc->exclusive)
 		return 0;
 	/*
 	 * If this group is exclusive and there are already
@@ -2616,36 +2610,29 @@ static void add_event_to_ctx(struct perf
 	perf_group_attach(event);
 }
 
-static void ctx_sched_out(struct perf_event_context *ctx,
-			  struct perf_cpu_context *cpuctx,
-			  enum event_type_t event_type);
-static void
-ctx_sched_in(struct perf_event_context *ctx,
-	     struct perf_cpu_context *cpuctx,
-	     enum event_type_t event_type);
-
-static void task_ctx_sched_out(struct perf_cpu_context *cpuctx,
-			       struct perf_event_context *ctx,
-			       enum event_type_t event_type)
+static void task_ctx_sched_out(struct perf_event_context *ctx,
+				enum event_type_t event_type)
 {
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
+
 	if (!cpuctx->task_ctx)
 		return;
 
 	if (WARN_ON_ONCE(ctx != cpuctx->task_ctx))
 		return;
 
-	ctx_sched_out(ctx, cpuctx, event_type);
+	ctx_sched_out(ctx, event_type);
 }
 
 static void perf_event_sched_in(struct perf_cpu_context *cpuctx,
 				struct perf_event_context *ctx)
 {
-	cpu_ctx_sched_in(cpuctx, EVENT_PINNED);
+	ctx_sched_in(&cpuctx->ctx, EVENT_PINNED);
 	if (ctx)
-		ctx_sched_in(ctx, cpuctx, EVENT_PINNED);
-	cpu_ctx_sched_in(cpuctx, EVENT_FLEXIBLE);
+		 ctx_sched_in(ctx, EVENT_PINNED);
+	ctx_sched_in(&cpuctx->ctx, EVENT_FLEXIBLE);
 	if (ctx)
-		ctx_sched_in(ctx, cpuctx, EVENT_FLEXIBLE);
+		 ctx_sched_in(ctx, EVENT_FLEXIBLE);
 }
 
 /*
@@ -2667,7 +2654,6 @@ static void ctx_resched(struct perf_cpu_
 			struct perf_event_context *task_ctx,
 			enum event_type_t event_type)
 {
-	enum event_type_t ctx_event_type;
 	bool cpu_event = !!(event_type & EVENT_CPU);
 
 	/*
@@ -2677,11 +2663,13 @@ static void ctx_resched(struct perf_cpu_
 	if (event_type & EVENT_PINNED)
 		event_type |= EVENT_FLEXIBLE;
 
-	ctx_event_type = event_type & EVENT_ALL;
+	event_type &= EVENT_ALL;
 
-	perf_pmu_disable(cpuctx->ctx.pmu);
-	if (task_ctx)
-		task_ctx_sched_out(cpuctx, task_ctx, event_type);
+	perf_ctx_disable(&cpuctx->ctx);
+	if (task_ctx) {
+		perf_ctx_disable(task_ctx);
+		task_ctx_sched_out(task_ctx, event_type);
+	}
 
 	/*
 	 * Decide which cpu ctx groups to schedule out based on the types
@@ -2691,17 +2679,20 @@ static void ctx_resched(struct perf_cpu_
 	 *  - otherwise, do nothing more.
 	 */
 	if (cpu_event)
-		cpu_ctx_sched_out(cpuctx, ctx_event_type);
-	else if (ctx_event_type & EVENT_PINNED)
-		cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+		ctx_sched_out(&cpuctx->ctx, event_type);
+	else if (event_type & EVENT_PINNED)
+		ctx_sched_out(&cpuctx->ctx, EVENT_FLEXIBLE);
 
 	perf_event_sched_in(cpuctx, task_ctx);
-	perf_pmu_enable(cpuctx->ctx.pmu);
+
+	perf_ctx_enable(&cpuctx->ctx);
+	if (task_ctx)
+		perf_ctx_enable(task_ctx);
 }
 
 void perf_pmu_resched(struct pmu *pmu)
 {
-	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	struct perf_event_context *task_ctx = cpuctx->task_ctx;
 
 	perf_ctx_lock(cpuctx, task_ctx);
@@ -2719,7 +2710,7 @@ static int  __perf_install_in_context(vo
 {
 	struct perf_event *event = info;
 	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	struct perf_event_context *task_ctx = cpuctx->task_ctx;
 	bool reprogram = true;
 	int ret = 0;
@@ -2761,7 +2752,7 @@ static int  __perf_install_in_context(vo
 #endif
 
 	if (reprogram) {
-		ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+		ctx_sched_out(ctx, EVENT_TIME);
 		add_event_to_ctx(event, ctx);
 		ctx_resched(cpuctx, task_ctx, get_event_type(event));
 	} else {
@@ -2909,7 +2900,7 @@ static void __perf_event_enable(struct p
 		return;
 
 	if (ctx->is_active)
-		ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+		ctx_sched_out(ctx, EVENT_TIME);
 
 	perf_event_set_state(event, PERF_EVENT_STATE_INACTIVE);
 	perf_cgroup_event_enable(event, ctx);
@@ -2918,7 +2909,7 @@ static void __perf_event_enable(struct p
 		return;
 
 	if (!event_filter_match(event)) {
-		ctx_sched_in(ctx, cpuctx, EVENT_TIME);
+		ctx_sched_in(ctx, EVENT_TIME);
 		return;
 	}
 
@@ -2927,7 +2918,7 @@ static void __perf_event_enable(struct p
 	 * then don't put it on unless the group is on.
 	 */
 	if (leader != event && leader->state != PERF_EVENT_STATE_ACTIVE) {
-		ctx_sched_in(ctx, cpuctx, EVENT_TIME);
+		ctx_sched_in(ctx, EVENT_TIME);
 		return;
 	}
 
@@ -3196,11 +3187,52 @@ static int perf_event_modify_attr(struct
 	return err;
 }
 
-static void ctx_sched_out(struct perf_event_context *ctx,
-			  struct perf_cpu_context *cpuctx,
-			  enum event_type_t event_type)
+static void __pmu_ctx_sched_out(struct perf_event_pmu_context *pmu_ctx,
+				enum event_type_t event_type)
 {
+	struct perf_event_context *ctx = pmu_ctx->ctx;
 	struct perf_event *event, *tmp;
+	struct pmu *pmu = pmu_ctx->pmu;
+
+	if (ctx->task && !ctx->is_active) {
+		struct perf_cpu_pmu_context *cpc;
+
+		cpc = this_cpu_ptr(pmu->cpu_pmu_context);
+		WARN_ON_ONCE(cpc->task_epc != pmu_ctx);
+		cpc->task_epc = NULL;
+	}
+
+	if (!event_type)
+		return;
+
+	perf_pmu_disable(pmu);
+	if (event_type & EVENT_PINNED) {
+		list_for_each_entry_safe(event, tmp,
+				&pmu_ctx->pinned_active,
+				active_list)
+			group_sched_out(event, ctx);
+	}
+
+	if (event_type & EVENT_FLEXIBLE) {
+		list_for_each_entry_safe(event, tmp,
+				&pmu_ctx->flexible_active,
+				active_list)
+			group_sched_out(event, ctx);
+		/*
+		 * Since we cleared EVENT_FLEXIBLE, also clear
+		 * rotate_necessary, is will be reset by
+		 * ctx_flexible_sched_in() when needed.
+		 */
+		pmu_ctx->rotate_necessary = 0;
+	}
+	perf_pmu_enable(pmu);
+}
+
+static void
+ctx_sched_out(struct perf_event_context *ctx, enum event_type_t event_type)
+{
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
+	struct perf_event_pmu_context *pmu_ctx;
 	int is_active = ctx->is_active;
 
 	lockdep_assert_held(&ctx->lock);
@@ -3251,24 +3283,8 @@ static void ctx_sched_out(struct perf_ev
 	if (!ctx->nr_active || !(is_active & EVENT_ALL))
 		return;
 
-	perf_pmu_disable(ctx->pmu);
-	if (is_active & EVENT_PINNED) {
-		list_for_each_entry_safe(event, tmp, &ctx->pinned_active, active_list)
-			group_sched_out(event, cpuctx, ctx);
-	}
-
-	if (is_active & EVENT_FLEXIBLE) {
-		list_for_each_entry_safe(event, tmp, &ctx->flexible_active, active_list)
-			group_sched_out(event, cpuctx, ctx);
-
-		/*
-		 * Since we cleared EVENT_FLEXIBLE, also clear
-		 * rotate_necessary, is will be reset by
-		 * ctx_flexible_sched_in() when needed.
-		 */
-		ctx->rotate_necessary = 0;
-	}
-	perf_pmu_enable(ctx->pmu);
+	list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry)
+		__pmu_ctx_sched_out(pmu_ctx, is_active);
 }
 
 /*
@@ -3373,26 +3389,65 @@ static void perf_event_sync_stat(struct
 	}
 }
 
-static void perf_event_context_sched_out(struct task_struct *task, int ctxn,
-					 struct task_struct *next)
+static void perf_event_swap_task_ctx_data(struct perf_event_context *prev_ctx,
+					  struct perf_event_context *next_ctx)
+{
+	struct perf_event_pmu_context *prev_epc, *next_epc;
+
+	if (!prev_ctx->nr_task_data)
+		return;
+
+	prev_epc = list_first_entry(&prev_ctx->pmu_ctx_list,
+				    struct perf_event_pmu_context,
+				    pmu_ctx_entry);
+	next_epc = list_first_entry(&next_ctx->pmu_ctx_list,
+				    struct perf_event_pmu_context,
+				    pmu_ctx_entry);
+
+	while (&prev_epc->pmu_ctx_entry != &prev_ctx->pmu_ctx_list &&
+	       &next_epc->pmu_ctx_entry != &next_ctx->pmu_ctx_list) {
+
+		WARN_ON_ONCE(prev_epc->pmu != next_epc->pmu);
+
+		/*
+		 * PMU specific parts of task perf context can require
+		 * additional synchronization. As an example of such
+		 * synchronization see implementation details of Intel
+		 * LBR call stack data profiling;
+		 */
+		if (prev_epc->pmu->swap_task_ctx)
+			prev_epc->pmu->swap_task_ctx(prev_epc, next_epc);
+		else
+			swap(prev_epc->task_ctx_data, next_epc->task_ctx_data);
+	}
+}
+
+static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, bool sched_in)
 {
-	struct perf_event_context *ctx = task->perf_event_ctxp[ctxn];
+	struct perf_event_pmu_context *pmu_ctx;
+	struct perf_cpu_pmu_context *cpc;
+
+	list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
+		cpc = this_cpu_ptr(pmu_ctx->pmu->cpu_pmu_context);
+
+		if (cpc->sched_cb_usage && pmu_ctx->pmu->sched_task)
+			pmu_ctx->pmu->sched_task(pmu_ctx, sched_in);
+	}
+}
+
+static void
+perf_event_context_sched_out(struct task_struct *task, struct task_struct *next)
+{
+	struct perf_event_context *ctx = task->perf_event_ctxp;
 	struct perf_event_context *next_ctx;
 	struct perf_event_context *parent, *next_parent;
-	struct perf_cpu_context *cpuctx;
 	int do_switch = 1;
-	struct pmu *pmu;
 
 	if (likely(!ctx))
 		return;
 
-	pmu = ctx->pmu;
-	cpuctx = __get_cpu_context(ctx);
-	if (!cpuctx->task_ctx)
-		return;
-
 	rcu_read_lock();
-	next_ctx = next->perf_event_ctxp[ctxn];
+	next_ctx = rcu_dereference(next->perf_event_ctxp);
 	if (!next_ctx)
 		goto unlock;
 
@@ -3420,23 +3475,12 @@ static void perf_event_context_sched_out
 			WRITE_ONCE(ctx->task, next);
 			WRITE_ONCE(next_ctx->task, task);
 
-			perf_pmu_disable(pmu);
+			perf_ctx_disable(ctx);
 
-			if (cpuctx->sched_cb_usage && pmu->sched_task)
-				pmu->sched_task(ctx, false);
+			perf_ctx_sched_task_cb(ctx, false);
+			perf_event_swap_task_ctx_data(ctx, next_ctx);
 
-			/*
-			 * PMU specific parts of task perf context can require
-			 * additional synchronization. As an example of such
-			 * synchronization see implementation details of Intel
-			 * LBR call stack data profiling;
-			 */
-			if (pmu->swap_task_ctx)
-				pmu->swap_task_ctx(ctx, next_ctx);
-			else
-				swap(ctx->task_ctx_data, next_ctx->task_ctx_data);
-
-			perf_pmu_enable(pmu);
+			perf_ctx_enable(ctx);
 
 			/*
 			 * RCU_INIT_POINTER here is safe because we've not
@@ -3445,8 +3489,8 @@ static void perf_event_context_sched_out
 			 * since those values are always verified under
 			 * ctx->lock which we're now holding.
 			 */
-			RCU_INIT_POINTER(task->perf_event_ctxp[ctxn], next_ctx);
-			RCU_INIT_POINTER(next->perf_event_ctxp[ctxn], ctx);
+			RCU_INIT_POINTER(task->perf_event_ctxp, next_ctx);
+			RCU_INIT_POINTER(next->perf_event_ctxp, ctx);
 
 			do_switch = 0;
 
@@ -3460,37 +3504,39 @@ static void perf_event_context_sched_out
 
 	if (do_switch) {
 		raw_spin_lock(&ctx->lock);
-		perf_pmu_disable(pmu);
+		perf_ctx_disable(ctx);
 
-		if (cpuctx->sched_cb_usage && pmu->sched_task)
-			pmu->sched_task(ctx, false);
-		task_ctx_sched_out(cpuctx, ctx, EVENT_ALL);
+		perf_ctx_sched_task_cb(ctx, false);
+		task_ctx_sched_out(ctx, EVENT_ALL);
 
-		perf_pmu_enable(pmu);
+		perf_ctx_enable(ctx);
 		raw_spin_unlock(&ctx->lock);
 	}
 }
 
 static DEFINE_PER_CPU(struct list_head, sched_cb_list);
+static DEFINE_PER_CPU(int, perf_sched_cb_usages);
 
 void perf_sched_cb_dec(struct pmu *pmu)
 {
-	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+	struct perf_cpu_pmu_context *cpc = this_cpu_ptr(pmu->cpu_pmu_context);
 
 	this_cpu_dec(perf_sched_cb_usages);
+	barrier();
 
-	if (!--cpuctx->sched_cb_usage)
-		list_del(&cpuctx->sched_cb_entry);
+	if (!--cpc->sched_cb_usage)
+		list_del(&cpc->sched_cb_entry);
 }
 
 
 void perf_sched_cb_inc(struct pmu *pmu)
 {
-	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+	struct perf_cpu_pmu_context *cpc = this_cpu_ptr(pmu->cpu_pmu_context);
 
-	if (!cpuctx->sched_cb_usage++)
-		list_add(&cpuctx->sched_cb_entry, this_cpu_ptr(&sched_cb_list));
+	if (!cpc->sched_cb_usage++)
+		list_add(&cpc->sched_cb_entry, this_cpu_ptr(&sched_cb_list));
 
+	barrier();
 	this_cpu_inc(perf_sched_cb_usages);
 }
 
@@ -3502,19 +3548,21 @@ void perf_sched_cb_inc(struct pmu *pmu)
  * PEBS requires this to provide PID/TID information. This requires we flush
  * all queued PEBS records before we context switch to a new task.
  */
-static void __perf_pmu_sched_task(struct perf_cpu_context *cpuctx, bool sched_in)
+static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, bool sched_in)
 {
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	struct pmu *pmu;
 
-	pmu = cpuctx->ctx.pmu; /* software PMUs will not have sched_task */
+	pmu = cpc->epc.pmu;
 
+	/* software PMUs will not have sched_task */
 	if (WARN_ON_ONCE(!pmu->sched_task))
 		return;
 
 	perf_ctx_lock(cpuctx, cpuctx->task_ctx);
 	perf_pmu_disable(pmu);
 
-	pmu->sched_task(cpuctx->task_ctx, sched_in);
+	pmu->sched_task(cpc->task_epc, sched_in);
 
 	perf_pmu_enable(pmu);
 	perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
@@ -3524,26 +3572,20 @@ static void perf_pmu_sched_task(struct t
 				struct task_struct *next,
 				bool sched_in)
 {
-	struct perf_cpu_context *cpuctx;
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
+	struct perf_cpu_pmu_context *cpc;
 
-	if (prev == next)
+	/* cpuctx->task_ctx will be handled in perf_event_context_sched_in/out */
+	if (prev == next || cpuctx->task_ctx)
 		return;
 
-	list_for_each_entry(cpuctx, this_cpu_ptr(&sched_cb_list), sched_cb_entry) {
-		/* will be handled in perf_event_context_sched_in/out */
-		if (cpuctx->task_ctx)
-			continue;
-
-		__perf_pmu_sched_task(cpuctx, sched_in);
-	}
+	list_for_each_entry(cpc, this_cpu_ptr(&sched_cb_list), sched_cb_entry)
+		__perf_pmu_sched_task(cpc, sched_in);
 }
 
 static void perf_event_switch(struct task_struct *task,
 			      struct task_struct *next_prev, bool sched_in);
 
-#define for_each_task_context_nr(ctxn)					\
-	for ((ctxn) = 0; (ctxn) < perf_nr_task_contexts; (ctxn)++)
-
 /*
  * Called from scheduler to remove the events of the current task,
  * with interrupts disabled.
@@ -3558,16 +3600,13 @@ static void perf_event_switch(struct tas
 void __perf_event_task_sched_out(struct task_struct *task,
 				 struct task_struct *next)
 {
-	int ctxn;
-
 	if (__this_cpu_read(perf_sched_cb_usages))
 		perf_pmu_sched_task(task, next, false);
 
 	if (atomic_read(&nr_switch_events))
 		perf_event_switch(task, next, false);
 
-	for_each_task_context_nr(ctxn)
-		perf_event_context_sched_out(task, ctxn, next);
+	perf_event_context_sched_out(task, next);
 
 	/*
 	 * if cgroup events exist on this CPU, then we need
@@ -3578,15 +3617,6 @@ void __perf_event_task_sched_out(struct
 		perf_cgroup_switch(next);
 }
 
-/*
- * Called with IRQs disabled
- */
-static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
-			      enum event_type_t event_type)
-{
-	ctx_sched_out(&cpuctx->ctx, cpuctx, event_type);
-}
-
 static bool perf_less_group_idx(const void *l, const void *r)
 {
 	const struct perf_event *le = *(const struct perf_event **)l;
@@ -3618,21 +3648,36 @@ static void __heap_add(struct min_heap *
 	}
 }
 
-static noinline int visit_groups_merge(struct perf_cpu_context *cpuctx,
+static void __link_epc(struct perf_event_pmu_context *pmu_ctx)
+{
+	struct perf_cpu_pmu_context *cpc;
+
+	if (!pmu_ctx->ctx->task)
+		return;
+
+	cpc = this_cpu_ptr(pmu_ctx->pmu->cpu_pmu_context);
+	WARN_ON_ONCE(cpc->task_epc && cpc->task_epc != pmu_ctx);
+	cpc->task_epc = pmu_ctx;
+}
+
+static noinline int visit_groups_merge(struct perf_event_context *ctx,
 				struct perf_event_groups *groups, int cpu,
+				struct pmu *pmu,
 				int (*func)(struct perf_event *, void *),
 				void *data)
 {
 #ifdef CONFIG_CGROUP_PERF
 	struct cgroup_subsys_state *css = NULL;
 #endif
+	struct perf_cpu_context *cpuctx = NULL;
 	/* Space for per CPU and/or any CPU event iterators. */
 	struct perf_event *itrs[2];
 	struct min_heap event_heap;
 	struct perf_event **evt;
 	int ret;
 
-	if (cpuctx) {
+	if (!ctx->task) {
+		cpuctx = this_cpu_ptr(&cpu_context);
 		event_heap = (struct min_heap){
 			.data = cpuctx->heap,
 			.nr = 0,
@@ -3652,17 +3697,28 @@ static noinline int visit_groups_merge(s
 			.size = ARRAY_SIZE(itrs),
 		};
 		/* Events not within a CPU context may be on any CPU. */
-		__heap_add(&event_heap, perf_event_groups_first(groups, -1, NULL));
+		__heap_add(&event_heap, perf_event_groups_first(groups, -1, pmu, NULL));
 	}
 	evt = event_heap.data;
 
-	__heap_add(&event_heap, perf_event_groups_first(groups, cpu, NULL));
+	__heap_add(&event_heap, perf_event_groups_first(groups, cpu, pmu, NULL));
 
 #ifdef CONFIG_CGROUP_PERF
 	for (; css; css = css->parent)
-		__heap_add(&event_heap, perf_event_groups_first(groups, cpu, css->cgroup));
+		__heap_add(&event_heap, perf_event_groups_first(groups, cpu, pmu, css->cgroup));
 #endif
 
+	if (event_heap.nr) {
+		/*
+		 * XXX: For now, visit_groups_merge() gets called with pmu
+		 * pointer never NULL. But these functions needs to be called
+		 * once for each pmu if I implement pmu=NULL optimization.
+		 */
+		__link_epc((*evt)->pmu_ctx);
+		perf_assert_pmu_disabled((*evt)->pmu_ctx->pmu);
+	}
+
+
 	min_heapify_all(&event_heap, &perf_min_heap);
 
 	while (event_heap.nr) {
@@ -3670,7 +3726,7 @@ static noinline int visit_groups_merge(s
 		if (ret)
 			return ret;
 
-		*evt = perf_event_groups_next(*evt);
+		*evt = perf_event_groups_next(*evt, pmu);
 		if (*evt)
 			min_heapify(&event_heap, 0, &perf_min_heap);
 		else
@@ -3712,7 +3768,6 @@ static inline void group_update_userpage
 static int merge_sched_in(struct perf_event *event, void *data)
 {
 	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
 	int *can_add_hw = data;
 
 	if (event->state <= PERF_EVENT_STATE_OFF)
@@ -3721,8 +3776,8 @@ static int merge_sched_in(struct perf_ev
 	if (!event_filter_match(event))
 		return 0;
 
-	if (group_can_go_on(event, cpuctx, *can_add_hw)) {
-		if (!group_sched_in(event, cpuctx, ctx))
+	if (group_can_go_on(event, *can_add_hw)) {
+		if (!group_sched_in(event, ctx))
 			list_add_tail(&event->active_list, get_event_list(event));
 	}
 
@@ -3732,8 +3787,11 @@ static int merge_sched_in(struct perf_ev
 			perf_cgroup_event_disable(event, ctx);
 			perf_event_set_state(event, PERF_EVENT_STATE_ERROR);
 		} else {
-			ctx->rotate_necessary = 1;
-			perf_mux_hrtimer_restart(cpuctx);
+			struct perf_cpu_pmu_context *cpc;
+
+			event->pmu_ctx->rotate_necessary = 1;
+			cpc = this_cpu_ptr(event->pmu_ctx->pmu->cpu_pmu_context);
+			perf_mux_hrtimer_restart(cpc);
 			group_update_userpage(event);
 		}
 	}
@@ -3741,39 +3799,67 @@ static int merge_sched_in(struct perf_ev
 	return 0;
 }
 
-static void
-ctx_pinned_sched_in(struct perf_event_context *ctx,
-		    struct perf_cpu_context *cpuctx)
+static void ctx_pinned_sched_in(struct perf_event_context *ctx, struct pmu *pmu)
 {
+	struct perf_event_pmu_context *pmu_ctx;
 	int can_add_hw = 1;
 
-	if (ctx != &cpuctx->ctx)
-		cpuctx = NULL;
-
-	visit_groups_merge(cpuctx, &ctx->pinned_groups,
-			   smp_processor_id(),
-			   merge_sched_in, &can_add_hw);
+	if (pmu) {
+		visit_groups_merge(ctx, &ctx->pinned_groups,
+				   smp_processor_id(), pmu,
+				   merge_sched_in, &can_add_hw);
+	} else {
+		/*
+		 * XXX: This can be optimized for per-task context by calling
+		 * visit_groups_merge() only once with:
+		 *   1) pmu=NULL
+		 *   2) Ignoring pmu in perf_event_groups_cmp() when it's NULL
+		 *   3) Making can_add_hw a per-pmu variable
+		 *
+		 * Though, it can not be opimized for per-cpu context because
+		 * per-cpu rb-tree consist of pmu-subtrees and pmu-subtrees
+		 * consist of cgroup-subtrees. i.e. a cgroup events of same
+		 * cgroup but different pmus are seperated out into respective
+		 * pmu-subtrees.
+		 */
+		list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
+			can_add_hw = 1;
+			visit_groups_merge(ctx, &ctx->pinned_groups,
+					   smp_processor_id(), pmu_ctx->pmu,
+					   merge_sched_in, &can_add_hw);
+		}
+	}
 }
 
-static void
-ctx_flexible_sched_in(struct perf_event_context *ctx,
-		      struct perf_cpu_context *cpuctx)
+/* XXX .busy thingy from Peter's patch */
+static void ctx_flexible_sched_in(struct perf_event_context *ctx, struct pmu *pmu)
 {
+	struct perf_event_pmu_context *pmu_ctx;
 	int can_add_hw = 1;
 
-	if (ctx != &cpuctx->ctx)
-		cpuctx = NULL;
+	if (pmu) {
+		visit_groups_merge(ctx, &ctx->flexible_groups,
+				   smp_processor_id(), pmu,
+				   merge_sched_in, &can_add_hw);
+	} else {
+		list_for_each_entry(pmu_ctx, &ctx->pmu_ctx_list, pmu_ctx_entry) {
+			can_add_hw = 1;
+			visit_groups_merge(ctx, &ctx->flexible_groups,
+					   smp_processor_id(), pmu_ctx->pmu,
+					   merge_sched_in, &can_add_hw);
+		}
+	}
+}
 
-	visit_groups_merge(cpuctx, &ctx->flexible_groups,
-			   smp_processor_id(),
-			   merge_sched_in, &can_add_hw);
+static void __pmu_ctx_sched_in(struct perf_event_context *ctx, struct pmu *pmu)
+{
+	ctx_flexible_sched_in(ctx, pmu);
 }
 
 static void
-ctx_sched_in(struct perf_event_context *ctx,
-	     struct perf_cpu_context *cpuctx,
-	     enum event_type_t event_type)
+ctx_sched_in(struct perf_event_context *ctx, enum event_type_t event_type)
 {
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	int is_active = ctx->is_active;
 
 	lockdep_assert_held(&ctx->lock);
@@ -3785,6 +3871,7 @@ ctx_sched_in(struct perf_event_context *
 		/* start ctx time */
 		__update_context_time(ctx, false);
 		perf_cgroup_set_timestamp(cpuctx);
+		// XXX ctx->task =? task
 		/*
 		 * CPU-release for the below ->is_active store,
 		 * see __load_acquire() in perf_event_time_now()
@@ -3807,39 +3894,32 @@ ctx_sched_in(struct perf_event_context *
 	 * in order to give them the best chance of going on.
 	 */
 	if (is_active & EVENT_PINNED)
-		ctx_pinned_sched_in(ctx, cpuctx);
+		ctx_pinned_sched_in(ctx, NULL);
 
 	/* Then walk through the lower prio flexible groups */
 	if (is_active & EVENT_FLEXIBLE)
-		ctx_flexible_sched_in(ctx, cpuctx);
+		ctx_flexible_sched_in(ctx, NULL);
 }
 
-static void cpu_ctx_sched_in(struct perf_cpu_context *cpuctx,
-			     enum event_type_t event_type)
+static void perf_event_context_sched_in(struct task_struct *task)
 {
-	struct perf_event_context *ctx = &cpuctx->ctx;
-
-	ctx_sched_in(ctx, cpuctx, event_type);
-}
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
+	struct perf_event_context *ctx;
 
-static void perf_event_context_sched_in(struct perf_event_context *ctx,
-					struct task_struct *task)
-{
-	struct perf_cpu_context *cpuctx;
-	struct pmu *pmu;
+	rcu_read_lock();
+	ctx = rcu_dereference(task->perf_event_ctxp);
+	if (!ctx)
+		goto rcu_unlock;
 
-	cpuctx = __get_cpu_context(ctx);
+	if (cpuctx->task_ctx == ctx) {
+		perf_ctx_lock(cpuctx, ctx);
+		perf_ctx_disable(ctx);
 
-	/*
-	 * HACK: for HETEROGENEOUS the task context might have switched to a
-	 * different PMU, force (re)set the context,
-	 */
-	pmu = ctx->pmu = cpuctx->ctx.pmu;
+		perf_ctx_sched_task_cb(ctx, true);
 
-	if (cpuctx->task_ctx == ctx) {
-		if (cpuctx->sched_cb_usage)
-			__perf_pmu_sched_task(cpuctx, true);
-		return;
+		perf_ctx_enable(ctx);
+		perf_ctx_unlock(cpuctx, ctx);
+		goto rcu_unlock;
 	}
 
 	perf_ctx_lock(cpuctx, ctx);
@@ -3850,7 +3930,7 @@ static void perf_event_context_sched_in(
 	if (!ctx->nr_events)
 		goto unlock;
 
-	perf_pmu_disable(pmu);
+	perf_ctx_disable(ctx);
 	/*
 	 * We want to keep the following priority order:
 	 * cpu pinned (that don't need to move), task pinned,
@@ -3859,17 +3939,24 @@ static void perf_event_context_sched_in(
 	 * However, if task's ctx is not carrying any pinned
 	 * events, no need to flip the cpuctx's events around.
 	 */
-	if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree))
-		cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+	if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree)) {
+		perf_ctx_disable(&cpuctx->ctx);
+		ctx_sched_out(&cpuctx->ctx, EVENT_FLEXIBLE);
+	}
+
 	perf_event_sched_in(cpuctx, ctx);
 
-	if (cpuctx->sched_cb_usage && pmu->sched_task)
-		pmu->sched_task(cpuctx->task_ctx, true);
+	perf_ctx_sched_task_cb(cpuctx->task_ctx, true);
 
-	perf_pmu_enable(pmu);
+	if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree))
+		perf_ctx_enable(&cpuctx->ctx);
+
+	perf_ctx_enable(ctx);
 
 unlock:
 	perf_ctx_unlock(cpuctx, ctx);
+rcu_unlock:
+	rcu_read_unlock();
 }
 
 /*
@@ -3886,16 +3973,7 @@ static void perf_event_context_sched_in(
 void __perf_event_task_sched_in(struct task_struct *prev,
 				struct task_struct *task)
 {
-	struct perf_event_context *ctx;
-	int ctxn;
-
-	for_each_task_context_nr(ctxn) {
-		ctx = task->perf_event_ctxp[ctxn];
-		if (likely(!ctx))
-			continue;
-
-		perf_event_context_sched_in(ctx, task);
-	}
+	perf_event_context_sched_in(task);
 
 	if (atomic_read(&nr_switch_events))
 		perf_event_switch(task, prev, true);
@@ -4014,8 +4092,8 @@ static void perf_adjust_period(struct pe
  * events. At the same time, make sure, having freq events does not change
  * the rate of unthrottling as that would introduce bias.
  */
-static void perf_adjust_freq_unthr_context(struct perf_event_context *ctx,
-					   int needs_unthr)
+static void
+perf_adjust_freq_unthr_context(struct perf_event_context *ctx, bool unthrottle)
 {
 	struct perf_event *event;
 	struct hw_perf_event *hwc;
@@ -4027,16 +4105,16 @@ static void perf_adjust_freq_unthr_conte
 	 * - context have events in frequency mode (needs freq adjust)
 	 * - there are events to unthrottle on this cpu
 	 */
-	if (!(ctx->nr_freq || needs_unthr))
+	if (!(ctx->nr_freq || unthrottle))
 		return;
 
 	raw_spin_lock(&ctx->lock);
-	perf_pmu_disable(ctx->pmu);
 
 	list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
 		if (event->state != PERF_EVENT_STATE_ACTIVE)
 			continue;
 
+		// XXX use visit thingy to avoid the -1,cpu match
 		if (!event_filter_match(event))
 			continue;
 
@@ -4077,7 +4155,6 @@ static void perf_adjust_freq_unthr_conte
 		perf_pmu_enable(event->pmu);
 	}
 
-	perf_pmu_enable(ctx->pmu);
 	raw_spin_unlock(&ctx->lock);
 }
 
@@ -4099,72 +4176,111 @@ static void rotate_ctx(struct perf_event
 
 /* pick an event from the flexible_groups to rotate */
 static inline struct perf_event *
-ctx_event_to_rotate(struct perf_event_context *ctx)
+ctx_event_to_rotate(struct perf_event_pmu_context *pmu_ctx)
 {
 	struct perf_event *event;
+	struct rb_node *node;
+	struct rb_root *tree;
+	struct __group_key key = {
+		.pmu = pmu_ctx->pmu,
+	};
 
 	/* pick the first active flexible event */
-	event = list_first_entry_or_null(&ctx->flexible_active,
+	event = list_first_entry_or_null(&pmu_ctx->flexible_active,
 					 struct perf_event, active_list);
+	if (event)
+		goto out;
 
 	/* if no active flexible event, pick the first event */
-	if (!event) {
-		event = rb_entry_safe(rb_first(&ctx->flexible_groups.tree),
-				      typeof(*event), group_node);
+	tree = &pmu_ctx->ctx->flexible_groups.tree;
+
+	if (!pmu_ctx->ctx->task) {
+		key.cpu = smp_processor_id();
+
+		node = rb_find_first(&key, tree, __group_cmp_ignore_cgroup);
+		if (node)
+			event = __node_2_pe(node);
+		goto out;
 	}
 
+	key.cpu = -1;
+	node = rb_find_first(&key, tree, __group_cmp_ignore_cgroup);
+	if (node) {
+		event = __node_2_pe(node);
+		goto out;
+	}
+
+	key.cpu = smp_processor_id();
+	node = rb_find_first(&key, tree, __group_cmp_ignore_cgroup);
+	if (node)
+		event = __node_2_pe(node);
+
+out:
 	/*
 	 * Unconditionally clear rotate_necessary; if ctx_flexible_sched_in()
 	 * finds there are unschedulable events, it will set it again.
 	 */
-	ctx->rotate_necessary = 0;
+	pmu_ctx->rotate_necessary = 0;
 
 	return event;
 }
 
-static bool perf_rotate_context(struct perf_cpu_context *cpuctx)
+static bool perf_rotate_context(struct perf_cpu_pmu_context *cpc)
 {
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
+	struct perf_event_pmu_context *cpu_epc, *task_epc = NULL;
 	struct perf_event *cpu_event = NULL, *task_event = NULL;
 	struct perf_event_context *task_ctx = NULL;
 	int cpu_rotate, task_rotate;
+	struct pmu *pmu;
 
 	/*
 	 * Since we run this from IRQ context, nobody can install new
 	 * events, thus the event count values are stable.
 	 */
 
-	cpu_rotate = cpuctx->ctx.rotate_necessary;
+	cpu_epc = &cpc->epc;
+	pmu = cpu_epc->pmu;
+	task_epc = cpc->task_epc;
+
+	cpu_rotate = cpu_epc->rotate_necessary;
 	task_ctx = cpuctx->task_ctx;
-	task_rotate = task_ctx ? task_ctx->rotate_necessary : 0;
+	task_rotate = task_epc ? task_epc->rotate_necessary : 0;
 
 	if (!(cpu_rotate || task_rotate))
 		return false;
 
 	perf_ctx_lock(cpuctx, cpuctx->task_ctx);
-	perf_pmu_disable(cpuctx->ctx.pmu);
+	perf_pmu_disable(pmu);
 
 	if (task_rotate)
-		task_event = ctx_event_to_rotate(task_ctx);
+		task_event = ctx_event_to_rotate(task_epc);
 	if (cpu_rotate)
-		cpu_event = ctx_event_to_rotate(&cpuctx->ctx);
+		cpu_event = ctx_event_to_rotate(cpu_epc);
 
 	/*
 	 * As per the order given at ctx_resched() first 'pop' task flexible
 	 * and then, if needed CPU flexible.
 	 */
-	if (task_event || (task_ctx && cpu_event))
-		ctx_sched_out(task_ctx, cpuctx, EVENT_FLEXIBLE);
-	if (cpu_event)
-		cpu_ctx_sched_out(cpuctx, EVENT_FLEXIBLE);
+	if (task_event || (task_epc && cpu_event)) {
+		update_context_time(task_epc->ctx);
+		__pmu_ctx_sched_out(task_epc, EVENT_FLEXIBLE);
+	}
 
-	if (task_event)
-		rotate_ctx(task_ctx, task_event);
-	if (cpu_event)
+	if (cpu_event) {
+		update_context_time(&cpuctx->ctx);
+		__pmu_ctx_sched_out(cpu_epc, EVENT_FLEXIBLE);
 		rotate_ctx(&cpuctx->ctx, cpu_event);
+		__pmu_ctx_sched_in(&cpuctx->ctx, pmu);
+	}
 
-	perf_event_sched_in(cpuctx, task_ctx);
+	if (task_event)
+		rotate_ctx(task_epc->ctx, task_event);
+
+	if (task_event || (task_epc && cpu_event))
+		__pmu_ctx_sched_in(task_epc->ctx, pmu);
 
-	perf_pmu_enable(cpuctx->ctx.pmu);
+	perf_pmu_enable(pmu);
 	perf_ctx_unlock(cpuctx, cpuctx->task_ctx);
 
 	return true;
@@ -4172,8 +4288,8 @@ static bool perf_rotate_context(struct p
 
 void perf_event_task_tick(void)
 {
-	struct list_head *head = this_cpu_ptr(&active_ctx_list);
-	struct perf_event_context *ctx, *tmp;
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
+	struct perf_event_context *ctx;
 	int throttled;
 
 	lockdep_assert_irqs_disabled();
@@ -4182,8 +4298,13 @@ void perf_event_task_tick(void)
 	throttled = __this_cpu_xchg(perf_throttled_count, 0);
 	tick_dep_clear_cpu(smp_processor_id(), TICK_DEP_BIT_PERF_EVENTS);
 
-	list_for_each_entry_safe(ctx, tmp, head, active_ctx_list)
-		perf_adjust_freq_unthr_context(ctx, throttled);
+	perf_adjust_freq_unthr_context(&cpuctx->ctx, !!throttled);
+
+	rcu_read_lock();
+	ctx = rcu_dereference(current->perf_event_ctxp);
+	if (ctx)
+		perf_adjust_freq_unthr_context(ctx, !!throttled);
+	rcu_read_unlock();
 }
 
 static int event_enable_on_exec(struct perf_event *event,
@@ -4205,9 +4326,9 @@ static int event_enable_on_exec(struct p
  * Enable all of a task's events that have been marked enable-on-exec.
  * This expects task == current.
  */
-static void perf_event_enable_on_exec(int ctxn)
+static void perf_event_enable_on_exec(struct perf_event_context *ctx)
 {
-	struct perf_event_context *ctx, *clone_ctx = NULL;
+	struct perf_event_context *clone_ctx = NULL;
 	enum event_type_t event_type = 0;
 	struct perf_cpu_context *cpuctx;
 	struct perf_event *event;
@@ -4215,13 +4336,16 @@ static void perf_event_enable_on_exec(in
 	int enabled = 0;
 
 	local_irq_save(flags);
-	ctx = current->perf_event_ctxp[ctxn];
-	if (!ctx || !ctx->nr_events)
+	if (WARN_ON_ONCE(current->perf_event_ctxp != ctx))
+		goto out;
+
+	if (!ctx->nr_events)
 		goto out;
 
-	cpuctx = __get_cpu_context(ctx);
+	cpuctx = this_cpu_ptr(&cpu_context);
 	perf_ctx_lock(cpuctx, ctx);
-	ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+	ctx_sched_out(ctx, EVENT_TIME);
+
 	list_for_each_entry(event, &ctx->event_list, event_entry) {
 		enabled |= event_enable_on_exec(event, ctx);
 		event_type |= get_event_type(event);
@@ -4234,7 +4358,7 @@ static void perf_event_enable_on_exec(in
 		clone_ctx = unclone_ctx(ctx);
 		ctx_resched(cpuctx, ctx, event_type);
 	} else {
-		ctx_sched_in(ctx, cpuctx, EVENT_TIME);
+		ctx_sched_in(ctx, EVENT_TIME);
 	}
 	perf_ctx_unlock(cpuctx, ctx);
 
@@ -4253,16 +4377,14 @@ static void perf_event_exit_event(struct
  * Removes all events from the current task that have been marked
  * remove-on-exec, and feeds their values back to parent events.
  */
-static void perf_event_remove_on_exec(int ctxn)
+static void perf_event_remove_on_exec(struct perf_event_context *ctx)
 {
-	struct perf_event_context *ctx, *clone_ctx = NULL;
+	struct perf_event_context *clone_ctx = NULL;
 	struct perf_event *event, *next;
 	unsigned long flags;
 	bool modified = false;
 
-	ctx = perf_pin_task_context(current, ctxn);
-	if (!ctx)
-		return;
+	perf_pin_task_context(current);
 
 	mutex_lock(&ctx->mutex);
 
@@ -4326,7 +4448,7 @@ static void __perf_event_read(void *info
 	struct perf_read_data *data = info;
 	struct perf_event *sub, *event = data->event;
 	struct perf_event_context *ctx = event->ctx;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	struct pmu *pmu = event->pmu;
 
 	/*
@@ -4552,17 +4674,25 @@ static void __perf_event_init_context(st
 {
 	raw_spin_lock_init(&ctx->lock);
 	mutex_init(&ctx->mutex);
-	INIT_LIST_HEAD(&ctx->active_ctx_list);
+	INIT_LIST_HEAD(&ctx->pmu_ctx_list);
 	perf_event_groups_init(&ctx->pinned_groups);
 	perf_event_groups_init(&ctx->flexible_groups);
 	INIT_LIST_HEAD(&ctx->event_list);
-	INIT_LIST_HEAD(&ctx->pinned_active);
-	INIT_LIST_HEAD(&ctx->flexible_active);
 	refcount_set(&ctx->refcount, 1);
 }
 
+static void
+__perf_init_event_pmu_context(struct perf_event_pmu_context *epc, struct pmu *pmu)
+{
+	epc->pmu = pmu;
+	INIT_LIST_HEAD(&epc->pmu_ctx_entry);
+	INIT_LIST_HEAD(&epc->pinned_active);
+	INIT_LIST_HEAD(&epc->flexible_active);
+	atomic_set(&epc->refcount, 1);
+}
+
 static struct perf_event_context *
-alloc_perf_context(struct pmu *pmu, struct task_struct *task)
+alloc_perf_context(struct task_struct *task)
 {
 	struct perf_event_context *ctx;
 
@@ -4573,7 +4703,6 @@ alloc_perf_context(struct pmu *pmu, stru
 	__perf_event_init_context(ctx);
 	if (task)
 		ctx->task = get_task_struct(task);
-	ctx->pmu = pmu;
 
 	return ctx;
 }
@@ -4602,15 +4731,12 @@ find_lively_task_by_vpid(pid_t vpid)
  * Returns a matching context with refcount and pincount.
  */
 static struct perf_event_context *
-find_get_context(struct pmu *pmu, struct task_struct *task,
-		struct perf_event *event)
+find_get_context(struct task_struct *task, struct perf_event *event)
 {
 	struct perf_event_context *ctx, *clone_ctx = NULL;
 	struct perf_cpu_context *cpuctx;
-	void *task_ctx_data = NULL;
 	unsigned long flags;
-	int ctxn, err;
-	int cpu = event->cpu;
+	int err;
 
 	if (!task) {
 		/* Must be root to operate on a CPU event: */
@@ -4618,7 +4744,7 @@ find_get_context(struct pmu *pmu, struct
 		if (err)
 			return ERR_PTR(err);
 
-		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
+		cpuctx = per_cpu_ptr(&cpu_context, event->cpu);
 		ctx = &cpuctx->ctx;
 		get_ctx(ctx);
 		raw_spin_lock_irqsave(&ctx->lock, flags);
@@ -4629,43 +4755,22 @@ find_get_context(struct pmu *pmu, struct
 	}
 
 	err = -EINVAL;
-	ctxn = pmu->task_ctx_nr;
-	if (ctxn < 0)
-		goto errout;
-
-	if (event->attach_state & PERF_ATTACH_TASK_DATA) {
-		task_ctx_data = alloc_task_ctx_data(pmu);
-		if (!task_ctx_data) {
-			err = -ENOMEM;
-			goto errout;
-		}
-	}
-
 retry:
-	ctx = perf_lock_task_context(task, ctxn, &flags);
+	ctx = perf_lock_task_context(task, &flags);
 	if (ctx) {
 		clone_ctx = unclone_ctx(ctx);
 		++ctx->pin_count;
 
-		if (task_ctx_data && !ctx->task_ctx_data) {
-			ctx->task_ctx_data = task_ctx_data;
-			task_ctx_data = NULL;
-		}
 		raw_spin_unlock_irqrestore(&ctx->lock, flags);
 
 		if (clone_ctx)
 			put_ctx(clone_ctx);
 	} else {
-		ctx = alloc_perf_context(pmu, task);
+		ctx = alloc_perf_context(task);
 		err = -ENOMEM;
 		if (!ctx)
 			goto errout;
 
-		if (task_ctx_data) {
-			ctx->task_ctx_data = task_ctx_data;
-			task_ctx_data = NULL;
-		}
-
 		err = 0;
 		mutex_lock(&task->perf_event_mutex);
 		/*
@@ -4674,12 +4779,12 @@ find_get_context(struct pmu *pmu, struct
 		 */
 		if (task->flags & PF_EXITING)
 			err = -ESRCH;
-		else if (task->perf_event_ctxp[ctxn])
+		else if (task->perf_event_ctxp)
 			err = -EAGAIN;
 		else {
 			get_ctx(ctx);
 			++ctx->pin_count;
-			rcu_assign_pointer(task->perf_event_ctxp[ctxn], ctx);
+			rcu_assign_pointer(task->perf_event_ctxp, ctx);
 		}
 		mutex_unlock(&task->perf_event_mutex);
 
@@ -4692,14 +4797,117 @@ find_get_context(struct pmu *pmu, struct
 		}
 	}
 
-	free_task_ctx_data(pmu, task_ctx_data);
 	return ctx;
 
 errout:
-	free_task_ctx_data(pmu, task_ctx_data);
 	return ERR_PTR(err);
 }
 
+struct perf_event_pmu_context *
+find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx,
+		     struct perf_event *event)
+{
+	struct perf_event_pmu_context *new = NULL, *epc;
+	void *task_ctx_data = NULL;
+
+	if (!ctx->task) {
+		struct perf_cpu_pmu_context *cpc;
+
+		cpc = per_cpu_ptr(pmu->cpu_pmu_context, event->cpu);
+		epc = &cpc->epc;
+
+		if (!epc->ctx) {
+			atomic_set(&epc->refcount, 1);
+			epc->embedded = 1;
+			raw_spin_lock_irq(&ctx->lock);
+			list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
+			epc->ctx = ctx;
+			raw_spin_unlock_irq(&ctx->lock);
+		} else {
+			WARN_ON_ONCE(epc->ctx != ctx);
+			atomic_inc(&epc->refcount);
+		}
+
+		return epc;
+	}
+
+	new = kzalloc(sizeof(*epc), GFP_KERNEL);
+	if (!new)
+		return ERR_PTR(-ENOMEM);
+
+	if (event->attach_state & PERF_ATTACH_TASK_DATA) {
+		task_ctx_data = alloc_task_ctx_data(pmu);;
+		if (!task_ctx_data) {
+			kfree(new);
+			return ERR_PTR(-ENOMEM);
+		}
+	}
+
+	__perf_init_event_pmu_context(new, pmu);
+
+	raw_spin_lock_irq(&ctx->lock);
+	list_for_each_entry(epc, &ctx->pmu_ctx_list, pmu_ctx_entry) {
+		if (epc->pmu == pmu) {
+			WARN_ON_ONCE(epc->ctx != ctx);
+			atomic_inc(&epc->refcount);
+			goto found_epc;
+		}
+	}
+
+	epc = new;
+	new = NULL;
+
+	list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list);
+	epc->ctx = ctx;
+
+found_epc:
+	if (task_ctx_data && !epc->task_ctx_data) {
+		epc->task_ctx_data = task_ctx_data;
+		task_ctx_data = NULL;
+		ctx->nr_task_data++;
+	}
+	raw_spin_unlock_irq(&ctx->lock);
+
+	free_task_ctx_data(pmu, task_ctx_data);
+	kfree(new);
+
+	return epc;
+}
+
+static void get_pmu_ctx(struct perf_event_pmu_context *epc)
+{
+	WARN_ON_ONCE(!atomic_inc_not_zero(&epc->refcount));
+}
+
+static void put_pmu_ctx(struct perf_event_pmu_context *epc)
+{
+	unsigned long flags;
+
+	if (!atomic_dec_and_test(&epc->refcount))
+		return;
+
+	if (epc->ctx) {
+		struct perf_event_context *ctx = epc->ctx;
+
+		// XXX ctx->mutex
+
+		WARN_ON_ONCE(list_empty(&epc->pmu_ctx_entry));
+		raw_spin_lock_irqsave(&ctx->lock, flags);
+		list_del_init(&epc->pmu_ctx_entry);
+		epc->ctx = NULL;
+		raw_spin_unlock_irqrestore(&ctx->lock, flags);
+	}
+
+	WARN_ON_ONCE(!list_empty(&epc->pinned_active));
+	WARN_ON_ONCE(!list_empty(&epc->flexible_active));
+
+	if (epc->embedded)
+		return;
+
+	kfree(epc->task_ctx_data);
+	kfree(epc);
+}
+
 static void perf_event_free_filter(struct perf_event *event);
 
 static void free_event_rcu(struct rcu_head *head)
@@ -4968,6 +5176,9 @@ static void _free_event(struct perf_even
 	if (event->hw.target)
 		put_task_struct(event->hw.target);
 
+	if (event->pmu_ctx)
+		put_pmu_ctx(event->pmu_ctx);
+
 	/*
 	 * perf_event_free_task() relies on put_ctx() being 'last', in particular
 	 * all task references must be cleaned up.
@@ -5498,7 +5709,7 @@ static void __perf_event_period(struct p
 
 	active = (event->state == PERF_EVENT_STATE_ACTIVE);
 	if (active) {
-		perf_pmu_disable(ctx->pmu);
+		perf_pmu_disable(event->pmu);
 		/*
 		 * We could be throttled; unthrottle now to avoid the tick
 		 * trying to unthrottle while we already re-started the event.
@@ -5514,7 +5725,7 @@ static void __perf_event_period(struct p
 
 	if (active) {
 		event->pmu->start(event, PERF_EF_RELOAD);
-		perf_pmu_enable(ctx->pmu);
+		perf_pmu_enable(event->pmu);
 	}
 }
 
@@ -7606,7 +7817,6 @@ perf_iterate_sb(perf_iterate_f output, v
 	       struct perf_event_context *task_ctx)
 {
 	struct perf_event_context *ctx;
-	int ctxn;
 
 	rcu_read_lock();
 	preempt_disable();
@@ -7623,11 +7833,9 @@ perf_iterate_sb(perf_iterate_f output, v
 
 	perf_iterate_sb_cpu(output, data);
 
-	for_each_task_context_nr(ctxn) {
-		ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
-		if (ctx)
-			perf_iterate_ctx(ctx, output, data, false);
-	}
+	ctx = rcu_dereference(current->perf_event_ctxp);
+	if (ctx)
+		perf_iterate_ctx(ctx, output, data, false);
 done:
 	preempt_enable();
 	rcu_read_unlock();
@@ -7669,20 +7877,15 @@ static void perf_event_addr_filters_exec
 void perf_event_exec(void)
 {
 	struct perf_event_context *ctx;
-	int ctxn;
-
-	for_each_task_context_nr(ctxn) {
-		perf_event_enable_on_exec(ctxn);
-		perf_event_remove_on_exec(ctxn);
 
-		rcu_read_lock();
-		ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
-		if (ctx) {
-			perf_iterate_ctx(ctx, perf_event_addr_filters_exec,
-					 NULL, true);
-		}
-		rcu_read_unlock();
+	rcu_read_lock();
+	ctx = rcu_dereference(current->perf_event_ctxp);
+	if (ctx) {
+		perf_event_enable_on_exec(ctx);
+		perf_event_remove_on_exec(ctx);
+		perf_iterate_ctx(ctx, perf_event_addr_filters_exec, NULL, true);
 	}
+	rcu_read_unlock();
 }
 
 struct remote_output {
@@ -7722,8 +7925,7 @@ static void __perf_event_output_stop(str
 static int __perf_pmu_output_stop(void *info)
 {
 	struct perf_event *event = info;
-	struct pmu *pmu = event->ctx->pmu;
-	struct perf_cpu_context *cpuctx = this_cpu_ptr(pmu->pmu_cpu_context);
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	struct remote_output ro = {
 		.rb	= event->rb,
 	};
@@ -8512,7 +8714,6 @@ static void __perf_addr_filters_adjust(s
 static void perf_addr_filters_adjust(struct vm_area_struct *vma)
 {
 	struct perf_event_context *ctx;
-	int ctxn;
 
 	/*
 	 * Data tracing isn't supported yet and as such there is no need
@@ -8522,13 +8723,9 @@ static void perf_addr_filters_adjust(str
 		return;
 
 	rcu_read_lock();
-	for_each_task_context_nr(ctxn) {
-		ctx = rcu_dereference(current->perf_event_ctxp[ctxn]);
-		if (!ctx)
-			continue;
-
+	ctx = rcu_dereference(current->perf_event_ctxp);
+	if (ctx)
 		perf_iterate_ctx(ctx, __perf_addr_filters_adjust, vma, true);
-	}
 	rcu_read_unlock();
 }
 
@@ -9737,10 +9934,13 @@ void perf_tp_event(u16 event_type, u64 c
 		struct trace_entry *entry = record;
 
 		rcu_read_lock();
-		ctx = rcu_dereference(task->perf_event_ctxp[perf_sw_context]);
+		ctx = rcu_dereference(task->perf_event_ctxp);
 		if (!ctx)
 			goto unlock;
 
+		// XXX iterate groups instead, we should be able to
+		// find the subtree for the perf_tracepoint pmu and CPU.
+
 		list_for_each_entry_rcu(event, &ctx->event_list, event_entry) {
 			if (event->cpu != smp_processor_id())
 				continue;
@@ -10873,36 +11073,9 @@ static int perf_event_idx_default(struct
 	return 0;
 }
 
-/*
- * Ensures all contexts with the same task_ctx_nr have the same
- * pmu_cpu_context too.
- */
-static struct perf_cpu_context __percpu *find_pmu_context(int ctxn)
-{
-	struct pmu *pmu;
-
-	if (ctxn < 0)
-		return NULL;
-
-	list_for_each_entry(pmu, &pmus, entry) {
-		if (pmu->task_ctx_nr == ctxn)
-			return pmu->pmu_cpu_context;
-	}
-
-	return NULL;
-}
-
 static void free_pmu_context(struct pmu *pmu)
 {
-	/*
-	 * Static contexts such as perf_sw_context have a global lifetime
-	 * and may be shared between different PMUs. Avoid freeing them
-	 * when a single PMU is going away.
-	 */
-	if (pmu->task_ctx_nr > perf_invalid_context)
-		return;
-
-	free_percpu(pmu->pmu_cpu_context);
+	free_percpu(pmu->cpu_pmu_context);
 }
 
 /*
@@ -10966,12 +11139,12 @@ perf_event_mux_interval_ms_store(struct
 	/* update all cpuctx for this PMU */
 	cpus_read_lock();
 	for_each_online_cpu(cpu) {
-		struct perf_cpu_context *cpuctx;
-		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
-		cpuctx->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * timer);
+		struct perf_cpu_pmu_context *cpc;
+		cpc = per_cpu_ptr(pmu->cpu_pmu_context, cpu);
+		cpc->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * timer);
 
 		cpu_function_call(cpu,
-			(remote_function_f)perf_mux_hrtimer_restart, cpuctx);
+			(remote_function_f)perf_mux_hrtimer_restart, cpc);
 	}
 	cpus_read_unlock();
 	mutex_unlock(&mux_interval_mutex);
@@ -11082,47 +11255,19 @@ int perf_pmu_register(struct pmu *pmu, c
 	}
 
 skip_type:
-	if (pmu->task_ctx_nr == perf_hw_context) {
-		static int hw_context_taken = 0;
-
-		/*
-		 * Other than systems with heterogeneous CPUs, it never makes
-		 * sense for two PMUs to share perf_hw_context. PMUs which are
-		 * uncore must use perf_invalid_context.
-		 */
-		if (WARN_ON_ONCE(hw_context_taken &&
-		    !(pmu->capabilities & PERF_PMU_CAP_HETEROGENEOUS_CPUS)))
-			pmu->task_ctx_nr = perf_invalid_context;
-
-		hw_context_taken = 1;
-	}
-
-	pmu->pmu_cpu_context = find_pmu_context(pmu->task_ctx_nr);
-	if (pmu->pmu_cpu_context)
-		goto got_cpu_context;
-
 	ret = -ENOMEM;
-	pmu->pmu_cpu_context = alloc_percpu(struct perf_cpu_context);
-	if (!pmu->pmu_cpu_context)
+	pmu->cpu_pmu_context = alloc_percpu(struct perf_cpu_pmu_context);
+	if (!pmu->cpu_pmu_context)
 		goto free_dev;
 
 	for_each_possible_cpu(cpu) {
-		struct perf_cpu_context *cpuctx;
-
-		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
-		__perf_event_init_context(&cpuctx->ctx);
-		lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
-		lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock);
-		cpuctx->ctx.pmu = pmu;
-		cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask);
-
-		__perf_mux_hrtimer_init(cpuctx, cpu);
+		struct perf_cpu_pmu_context *cpc;
 
-		cpuctx->heap_size = ARRAY_SIZE(cpuctx->heap_default);
-		cpuctx->heap = cpuctx->heap_default;
+		cpc = per_cpu_ptr(pmu->cpu_pmu_context, cpu);
+		__perf_init_event_pmu_context(&cpc->epc, pmu);
+		__perf_mux_hrtimer_init(cpc, cpu);
 	}
 
-got_cpu_context:
 	if (!pmu->start_txn) {
 		if (pmu->pmu_enable) {
 			/*
@@ -11604,10 +11749,11 @@ perf_event_alloc(struct perf_event_attr
 	}
 
 	/*
-	 * Disallow uncore-cgroup events, they don't make sense as the cgroup will
-	 * be different on other CPUs in the uncore mask.
+	 * Disallow uncode-task events. Similarly, disallow uncore-cgroup
+	 * events (they don't make sense as the cgroup will be different
+	 * on other CPUs in the uncore mask).
 	 */
-	if (pmu->task_ctx_nr == perf_invalid_context && cgroup_fd != -1) {
+	if (pmu->task_ctx_nr == perf_invalid_context && (task || cgroup_fd != -1)) {
 		err = -EINVAL;
 		goto err_pmu;
 	}
@@ -11893,15 +12039,6 @@ perf_event_set_output(struct perf_event
 	return ret;
 }
 
-static void mutex_lock_double(struct mutex *a, struct mutex *b)
-{
-	if (b < a)
-		swap(a, b);
-
-	mutex_lock(a);
-	mutex_lock_nested(b, SINGLE_DEPTH_NESTING);
-}
-
 static int perf_event_set_clock(struct perf_event *event, clockid_t clk_id)
 {
 	bool nmi_safe = false;
@@ -11939,37 +12076,6 @@ static int perf_event_set_clock(struct p
 	return 0;
 }
 
-/*
- * Variation on perf_event_ctx_lock_nested(), except we take two context
- * mutexes.
- */
-static struct perf_event_context *
-__perf_event_ctx_lock_double(struct perf_event *group_leader,
-			     struct perf_event_context *ctx)
-{
-	struct perf_event_context *gctx;
-
-again:
-	rcu_read_lock();
-	gctx = READ_ONCE(group_leader->ctx);
-	if (!refcount_inc_not_zero(&gctx->refcount)) {
-		rcu_read_unlock();
-		goto again;
-	}
-	rcu_read_unlock();
-
-	mutex_lock_double(&gctx->mutex, &ctx->mutex);
-
-	if (group_leader->ctx != gctx) {
-		mutex_unlock(&ctx->mutex);
-		mutex_unlock(&gctx->mutex);
-		put_ctx(gctx);
-		goto again;
-	}
-
-	return gctx;
-}
-
 static bool
 perf_check_permission(struct perf_event_attr *attr, struct task_struct *task)
 {
@@ -12015,9 +12121,10 @@ SYSCALL_DEFINE5(perf_event_open,
 		pid_t, pid, int, cpu, int, group_fd, unsigned long, flags)
 {
 	struct perf_event *group_leader = NULL, *output_event = NULL;
+	struct perf_event_pmu_context *pmu_ctx;
 	struct perf_event *event, *sibling;
 	struct perf_event_attr attr;
-	struct perf_event_context *ctx, *gctx;
+	struct perf_event_context *ctx;
 	struct file *event_file = NULL;
 	struct fd group = {NULL, 0};
 	struct task_struct *task = NULL;
@@ -12125,6 +12232,8 @@ SYSCALL_DEFINE5(perf_event_open,
 		goto err_task;
 	}
 
+	// XXX premature; what if this is allowed, but we get moved to a PMU
+	// that doesn't have this.
 	if (is_sampling_event(event)) {
 		if (event->pmu->capabilities & PERF_PMU_CAP_NO_INTERRUPT) {
 			err = -EOPNOTSUPP;
@@ -12147,42 +12256,37 @@ SYSCALL_DEFINE5(perf_event_open,
 	if (pmu->task_ctx_nr == perf_sw_context)
 		event->event_caps |= PERF_EV_CAP_SOFTWARE;
 
-	if (group_leader) {
-		if (is_software_event(event) &&
-		    !in_software_context(group_leader)) {
-			/*
-			 * If the event is a sw event, but the group_leader
-			 * is on hw context.
-			 *
-			 * Allow the addition of software events to hw
-			 * groups, this is safe because software events
-			 * never fail to schedule.
-			 */
-			pmu = group_leader->ctx->pmu;
-		} else if (!is_software_event(event) &&
-			   is_software_event(group_leader) &&
-			   (group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
-			/*
-			 * In case the group is a pure software group, and we
-			 * try to add a hardware event, move the whole group to
-			 * the hardware context.
-			 */
-			move_group = 1;
-		}
-	}
-
 	/*
 	 * Get the target context (task or percpu):
 	 */
-	ctx = find_get_context(pmu, task, event);
+	ctx = find_get_context(task, event);
 	if (IS_ERR(ctx)) {
 		err = PTR_ERR(ctx);
 		goto err_alloc;
 	}
 
-	/*
-	 * Look up the group leader (we will attach this event to it):
-	 */
+	mutex_lock(&ctx->mutex);
+
+	if (ctx->task == TASK_TOMBSTONE) {
+		err = -ESRCH;
+		goto err_locked;
+	}
+
+	if (!task) {
+		/*
+		 * Check if the @cpu we're creating an event for is online.
+		 *
+		 * We use the perf_cpu_context::ctx::mutex to serialize against
+		 * the hotplug notifiers. See perf_event_{init,exit}_cpu().
+		 */
+		struct perf_cpu_context *cpuctx = per_cpu_ptr(&cpu_context, event->cpu);
+
+		if (!cpuctx->online) {
+			err = -ENODEV;
+			goto err_locked;
+		}
+	}
+
 	if (group_leader) {
 		err = -EINVAL;
 
@@ -12191,11 +12295,11 @@ SYSCALL_DEFINE5(perf_event_open,
 		 * becoming part of another group-sibling):
 		 */
 		if (group_leader->group_leader != group_leader)
-			goto err_context;
+			goto err_locked;
 
 		/* All events in a group should have the same clock */
 		if (group_leader->clock != event->clock)
-			goto err_context;
+			goto err_locked;
 
 		/*
 		 * Make sure we're both events for the same CPU;
@@ -12203,41 +12307,60 @@ SYSCALL_DEFINE5(perf_event_open,
 		 * you can never concurrently schedule them anyhow.
 		 */
 		if (group_leader->cpu != event->cpu)
-			goto err_context;
-
-		/*
-		 * Make sure we're both on the same task, or both
-		 * per-CPU events.
-		 */
-		if (group_leader->ctx->task != ctx->task)
-			goto err_context;
+			goto err_locked;
 
 		/*
-		 * Do not allow to attach to a group in a different task
-		 * or CPU context. If we're moving SW events, we'll fix
-		 * this up later, so allow that.
-		 *
-		 * Racy, not holding group_leader->ctx->mutex, see comment with
-		 * perf_event_ctx_lock().
+		 * Make sure we're both on the same context; either task or cpu.
 		 */
-		if (!move_group && group_leader->ctx != ctx)
-			goto err_context;
+		if (group_leader->ctx != ctx)
+			goto err_locked;
 
 		/*
 		 * Only a group leader can be exclusive or pinned
 		 */
 		if (attr.exclusive || attr.pinned)
-			goto err_context;
+			goto err_locked;
+
+		if (is_software_event(event) &&
+		    !in_software_context(group_leader)) {
+			/*
+			 * If the event is a sw event, but the group_leader
+			 * is on hw context.
+			 *
+			 * Allow the addition of software events to hw
+			 * groups, this is safe because software events
+			 * never fail to schedule.
+			 */
+			pmu = group_leader->pmu_ctx->pmu;
+		} else if (!is_software_event(event) &&
+			is_software_event(group_leader) &&
+			(group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
+			/*
+			 * In case the group is a pure software group, and we
+			 * try to add a hardware event, move the whole group to
+			 * the hardware context.
+			 */
+			move_group = 1;
+		}
 	}
 
+	/*
+	 * Now that we're certain of the pmu; find the pmu_ctx.
+	 */
+	pmu_ctx = find_get_pmu_context(pmu, ctx, event);
+	if (IS_ERR(pmu_ctx)) {
+		err = PTR_ERR(pmu_ctx);
+		goto err_locked;
+	}
+	event->pmu_ctx = pmu_ctx;
+
 	if (output_event) {
 		err = perf_event_set_output(event, output_event);
 		if (err)
 			goto err_context;
 	}
 
-	event_file = anon_inode_getfile("[perf_event]", &perf_fops, event,
-					f_flags);
+	event_file = anon_inode_getfile("[perf_event]", &perf_fops, event, f_flags);
 	if (IS_ERR(event_file)) {
 		err = PTR_ERR(event_file);
 		event_file = NULL;
@@ -12260,59 +12383,6 @@ SYSCALL_DEFINE5(perf_event_open,
 			goto err_cred;
 	}
 
-	if (move_group) {
-		gctx = __perf_event_ctx_lock_double(group_leader, ctx);
-
-		if (gctx->task == TASK_TOMBSTONE) {
-			err = -ESRCH;
-			goto err_locked;
-		}
-
-		/*
-		 * Check if we raced against another sys_perf_event_open() call
-		 * moving the software group underneath us.
-		 */
-		if (!(group_leader->group_caps & PERF_EV_CAP_SOFTWARE)) {
-			/*
-			 * If someone moved the group out from under us, check
-			 * if this new event wound up on the same ctx, if so
-			 * its the regular !move_group case, otherwise fail.
-			 */
-			if (gctx != ctx) {
-				err = -EINVAL;
-				goto err_locked;
-			} else {
-				perf_event_ctx_unlock(group_leader, gctx);
-				move_group = 0;
-				goto not_move_group;
-			}
-		}
-
-		/*
-		 * Failure to create exclusive events returns -EBUSY.
-		 */
-		err = -EBUSY;
-		if (!exclusive_event_installable(group_leader, ctx))
-			goto err_locked;
-
-		for_each_sibling_event(sibling, group_leader) {
-			if (!exclusive_event_installable(sibling, ctx))
-				goto err_locked;
-		}
-	} else {
-		mutex_lock(&ctx->mutex);
-
-		/*
-		 * Now that we hold ctx->lock, (re)validate group_leader->ctx == ctx,
-		 * see the group_leader && !move_group test earlier.
-		 */
-		if (group_leader && group_leader->ctx != ctx) {
-			err = -EINVAL;
-			goto err_locked;
-		}
-	}
-not_move_group:
-
 	if (ctx->task == TASK_TOMBSTONE) {
 		err = -ESRCH;
 		goto err_locked;
@@ -12350,7 +12420,7 @@ SYSCALL_DEFINE5(perf_event_open,
 	 */
 	if (!exclusive_event_installable(event, ctx)) {
 		err = -EBUSY;
-		goto err_locked;
+		goto err_cred;
 	}
 
 	WARN_ON_ONCE(ctx->parent_ctx);
@@ -12361,25 +12431,15 @@ SYSCALL_DEFINE5(perf_event_open,
 	 */
 
 	if (move_group) {
-		/*
-		 * See perf_event_ctx_lock() for comments on the details
-		 * of swizzling perf_event::ctx.
-		 */
 		perf_remove_from_context(group_leader, 0);
-		put_ctx(gctx);
+		put_pmu_ctx(group_leader->pmu_ctx);
 
 		for_each_sibling_event(sibling, group_leader) {
 			perf_remove_from_context(sibling, 0);
-			put_ctx(gctx);
+			put_pmu_ctx(sibling->pmu_ctx);
 		}
 
 		/*
-		 * Wait for everybody to stop referencing the events through
-		 * the old lists, before installing it on new lists.
-		 */
-		synchronize_rcu();
-
-		/*
 		 * Install the group siblings before the group leader.
 		 *
 		 * Because a group leader will try and install the entire group
@@ -12390,9 +12450,10 @@ SYSCALL_DEFINE5(perf_event_open,
 		 * reachable through the group lists.
 		 */
 		for_each_sibling_event(sibling, group_leader) {
+			sibling->pmu_ctx = pmu_ctx;
+			get_pmu_ctx(pmu_ctx);
 			perf_event__state_init(sibling);
 			perf_install_in_context(ctx, sibling, sibling->cpu);
-			get_ctx(ctx);
 		}
 
 		/*
@@ -12400,9 +12461,10 @@ SYSCALL_DEFINE5(perf_event_open,
 		 * event. What we want here is event in the initial
 		 * startup state, ready to be add into new context.
 		 */
+		group_leader->pmu_ctx = pmu_ctx;
+		get_pmu_ctx(pmu_ctx);
 		perf_event__state_init(group_leader);
 		perf_install_in_context(ctx, group_leader, group_leader->cpu);
-		get_ctx(ctx);
 	}
 
 	/*
@@ -12419,8 +12481,6 @@ SYSCALL_DEFINE5(perf_event_open,
 	perf_install_in_context(ctx, event, event->cpu);
 	perf_unpin_context(ctx);
 
-	if (move_group)
-		perf_event_ctx_unlock(group_leader, gctx);
 	mutex_unlock(&ctx->mutex);
 
 	if (task) {
@@ -12442,16 +12502,15 @@ SYSCALL_DEFINE5(perf_event_open,
 	fd_install(event_fd, event_file);
 	return event_fd;
 
-err_locked:
-	if (move_group)
-		perf_event_ctx_unlock(group_leader, gctx);
-	mutex_unlock(&ctx->mutex);
 err_cred:
 	if (task)
 		up_read(&task->signal->exec_update_lock);
 err_file:
 	fput(event_file);
 err_context:
+	/* event->pmu_ctx freed by free_event() */
+err_locked:
+	mutex_unlock(&ctx->mutex);
 	perf_unpin_context(ctx);
 	put_ctx(ctx);
 err_alloc:
@@ -12486,8 +12545,10 @@ perf_event_create_kernel_counter(struct
 				 perf_overflow_handler_t overflow_handler,
 				 void *context)
 {
+	struct perf_event_pmu_context *pmu_ctx;
 	struct perf_event_context *ctx;
 	struct perf_event *event;
+	struct pmu *pmu;
 	int err;
 
 	/*
@@ -12506,16 +12567,32 @@ perf_event_create_kernel_counter(struct
 
 	/* Mark owner so we could distinguish it from user events. */
 	event->owner = TASK_TOMBSTONE;
+	pmu = event->pmu;
+
+	if (pmu->task_ctx_nr < 0 && task) {
+		err = -EINVAL;
+		goto err_alloc;
+	}
+
+	if (pmu->task_ctx_nr == perf_sw_context)
+		event->event_caps |= PERF_EV_CAP_SOFTWARE;
 
 	/*
 	 * Get the target context (task or percpu):
 	 */
-	ctx = find_get_context(event->pmu, task, event);
+	ctx = find_get_context(task, event);
 	if (IS_ERR(ctx)) {
 		err = PTR_ERR(ctx);
-		goto err_free;
+		goto err_alloc;
 	}
 
+	pmu_ctx = find_get_pmu_context(pmu, ctx, event);
+	if (IS_ERR(pmu_ctx)) {
+		err = PTR_ERR(pmu_ctx);
+		goto err_ctx;
+	}
+	event->pmu_ctx = pmu_ctx;
+
 	WARN_ON_ONCE(ctx->parent_ctx);
 	mutex_lock(&ctx->mutex);
 	if (ctx->task == TASK_TOMBSTONE) {
@@ -12551,9 +12628,10 @@ perf_event_create_kernel_counter(struct
 
 err_unlock:
 	mutex_unlock(&ctx->mutex);
+err_ctx:
 	perf_unpin_context(ctx);
 	put_ctx(ctx);
-err_free:
+err_alloc:
 	free_event(event);
 err:
 	return ERR_PTR(err);
@@ -12562,6 +12640,7 @@ EXPORT_SYMBOL_GPL(perf_event_create_kern
 
 void perf_pmu_migrate_context(struct pmu *pmu, int src_cpu, int dst_cpu)
 {
+#if 0 // XXX buggered - cpu hotplug, who cares
 	struct perf_event_context *src_ctx;
 	struct perf_event_context *dst_ctx;
 	struct perf_event *event, *tmp;
@@ -12622,6 +12701,7 @@ void perf_pmu_migrate_context(struct pmu
 	}
 	mutex_unlock(&dst_ctx->mutex);
 	mutex_unlock(&src_ctx->mutex);
+#endif
 }
 EXPORT_SYMBOL_GPL(perf_pmu_migrate_context);
 
@@ -12699,14 +12779,14 @@ perf_event_exit_event(struct perf_event
 	perf_event_wakeup(event);
 }
 
-static void perf_event_exit_task_context(struct task_struct *child, int ctxn)
+static void perf_event_exit_task_context(struct task_struct *child)
 {
 	struct perf_event_context *child_ctx, *clone_ctx = NULL;
 	struct perf_event *child_event, *next;
 
 	WARN_ON_ONCE(child != current);
 
-	child_ctx = perf_pin_task_context(child, ctxn);
+	child_ctx = perf_pin_task_context(child);
 	if (!child_ctx)
 		return;
 
@@ -12728,13 +12808,13 @@ static void perf_event_exit_task_context
 	 * in.
 	 */
 	raw_spin_lock_irq(&child_ctx->lock);
-	task_ctx_sched_out(__get_cpu_context(child_ctx), child_ctx, EVENT_ALL);
+	task_ctx_sched_out(child_ctx, EVENT_ALL);
 
 	/*
 	 * Now that the context is inactive, destroy the task <-> ctx relation
 	 * and mark the context dead.
 	 */
-	RCU_INIT_POINTER(child->perf_event_ctxp[ctxn], NULL);
+	RCU_INIT_POINTER(child->perf_event_ctxp, NULL);
 	put_ctx(child_ctx); /* cannot be last */
 	WRITE_ONCE(child_ctx->task, TASK_TOMBSTONE);
 	put_task_struct(current); /* cannot be last */
@@ -12769,7 +12849,6 @@ static void perf_event_exit_task_context
 void perf_event_exit_task(struct task_struct *child)
 {
 	struct perf_event *event, *tmp;
-	int ctxn;
 
 	mutex_lock(&child->perf_event_mutex);
 	list_for_each_entry_safe(event, tmp, &child->perf_event_list,
@@ -12785,8 +12864,7 @@ void perf_event_exit_task(struct task_st
 	}
 	mutex_unlock(&child->perf_event_mutex);
 
-	for_each_task_context_nr(ctxn)
-		perf_event_exit_task_context(child, ctxn);
+	perf_event_exit_task_context(child);
 
 	/*
 	 * The perf_event_exit_task_context calls perf_event_task
@@ -12829,56 +12907,51 @@ void perf_event_free_task(struct task_st
 {
 	struct perf_event_context *ctx;
 	struct perf_event *event, *tmp;
-	int ctxn;
 
-	for_each_task_context_nr(ctxn) {
-		ctx = task->perf_event_ctxp[ctxn];
-		if (!ctx)
-			continue;
+	ctx = rcu_dereference(task->perf_event_ctxp);
+	if (!ctx)
+		return;
 
-		mutex_lock(&ctx->mutex);
-		raw_spin_lock_irq(&ctx->lock);
-		/*
-		 * Destroy the task <-> ctx relation and mark the context dead.
-		 *
-		 * This is important because even though the task hasn't been
-		 * exposed yet the context has been (through child_list).
-		 */
-		RCU_INIT_POINTER(task->perf_event_ctxp[ctxn], NULL);
-		WRITE_ONCE(ctx->task, TASK_TOMBSTONE);
-		put_task_struct(task); /* cannot be last */
-		raw_spin_unlock_irq(&ctx->lock);
+	mutex_lock(&ctx->mutex);
+	raw_spin_lock_irq(&ctx->lock);
+	/*
+	 * Destroy the task <-> ctx relation and mark the context dead.
+	 *
+	 * This is important because even though the task hasn't been
+	 * exposed yet the context has been (through child_list).
+	 */
+	RCU_INIT_POINTER(task->perf_event_ctxp, NULL);
+	WRITE_ONCE(ctx->task, TASK_TOMBSTONE);
+	put_task_struct(task); /* cannot be last */
+	raw_spin_unlock_irq(&ctx->lock);
 
-		list_for_each_entry_safe(event, tmp, &ctx->event_list, event_entry)
-			perf_free_event(event, ctx);
 
-		mutex_unlock(&ctx->mutex);
+	list_for_each_entry_safe(event, tmp, &ctx->event_list, event_entry)
+		perf_free_event(event, ctx);
 
-		/*
-		 * perf_event_release_kernel() could've stolen some of our
-		 * child events and still have them on its free_list. In that
-		 * case we must wait for these events to have been freed (in
-		 * particular all their references to this task must've been
-		 * dropped).
-		 *
-		 * Without this copy_process() will unconditionally free this
-		 * task (irrespective of its reference count) and
-		 * _free_event()'s put_task_struct(event->hw.target) will be a
-		 * use-after-free.
-		 *
-		 * Wait for all events to drop their context reference.
-		 */
-		wait_var_event(&ctx->refcount, refcount_read(&ctx->refcount) == 1);
-		put_ctx(ctx); /* must be last */
-	}
+	mutex_unlock(&ctx->mutex);
+
+	/*
+	 * perf_event_release_kernel() could've stolen some of our
+	 * child events and still have them on its free_list. In that
+	 * case we must wait for these events to have been freed (in
+	 * particular all their references to this task must've been
+	 * dropped).
+	 *
+	 * Without this copy_process() will unconditionally free this
+	 * task (irrespective of its reference count) and
+	 * _free_event()'s put_task_struct(event->hw.target) will be a
+	 * use-after-free.
+	 *
+	 * Wait for all events to drop their context reference.
+	 */
+	wait_var_event(&ctx->refcount, refcount_read(&ctx->refcount) == 1);
+	put_ctx(ctx); /* must be last */
 }
 
 void perf_event_delayed_put(struct task_struct *task)
 {
-	int ctxn;
-
-	for_each_task_context_nr(ctxn)
-		WARN_ON_ONCE(task->perf_event_ctxp[ctxn]);
+	WARN_ON_ONCE(task->perf_event_ctxp);
 }
 
 struct file *perf_event_get(unsigned int fd)
@@ -12928,6 +13001,7 @@ inherit_event(struct perf_event *parent_
 	      struct perf_event_context *child_ctx)
 {
 	enum perf_event_state parent_state = parent_event->state;
+	struct perf_event_pmu_context *pmu_ctx;
 	struct perf_event *child_event;
 	unsigned long flags;
 
@@ -12948,17 +13022,12 @@ inherit_event(struct perf_event *parent_
 	if (IS_ERR(child_event))
 		return child_event;
 
-
-	if ((child_event->attach_state & PERF_ATTACH_TASK_DATA) &&
-	    !child_ctx->task_ctx_data) {
-		struct pmu *pmu = child_event->pmu;
-
-		child_ctx->task_ctx_data = alloc_task_ctx_data(pmu);
-		if (!child_ctx->task_ctx_data) {
-			free_event(child_event);
-			return ERR_PTR(-ENOMEM);
-		}
+	pmu_ctx = find_get_pmu_context(child_event->pmu, child_ctx, child_event);
+	if (!pmu_ctx) {
+		free_event(child_event);
+		return NULL;
 	}
+	child_event->pmu_ctx = pmu_ctx;
 
 	/*
 	 * is_orphaned_event() and list_add_tail(&parent_event->child_list)
@@ -13081,11 +13150,11 @@ static int inherit_group(struct perf_eve
 static int
 inherit_task_group(struct perf_event *event, struct task_struct *parent,
 		   struct perf_event_context *parent_ctx,
-		   struct task_struct *child, int ctxn,
+		   struct task_struct *child,
 		   u64 clone_flags, int *inherited_all)
 {
-	int ret;
 	struct perf_event_context *child_ctx;
+	int ret;
 
 	if (!event->attr.inherit ||
 	    (event->attr.inherit_thread && !(clone_flags & CLONE_THREAD)) ||
@@ -13095,7 +13164,7 @@ inherit_task_group(struct perf_event *ev
 		return 0;
 	}
 
-	child_ctx = child->perf_event_ctxp[ctxn];
+	child_ctx = child->perf_event_ctxp;
 	if (!child_ctx) {
 		/*
 		 * This is executed from the parent task context, so
@@ -13103,16 +13172,14 @@ inherit_task_group(struct perf_event *ev
 		 * First allocate and initialize a context for the
 		 * child.
 		 */
-		child_ctx = alloc_perf_context(parent_ctx->pmu, child);
+		child_ctx = alloc_perf_context(child);
 		if (!child_ctx)
 			return -ENOMEM;
 
-		child->perf_event_ctxp[ctxn] = child_ctx;
+		child->perf_event_ctxp = child_ctx;
 	}
 
-	ret = inherit_group(event, parent, parent_ctx,
-			    child, child_ctx);
-
+	ret = inherit_group(event, parent, parent_ctx, child, child_ctx);
 	if (ret)
 		*inherited_all = 0;
 
@@ -13122,8 +13189,7 @@ inherit_task_group(struct perf_event *ev
 /*
  * Initialize the perf_event context in task_struct
  */
-static int perf_event_init_context(struct task_struct *child, int ctxn,
-				   u64 clone_flags)
+static int perf_event_init_context(struct task_struct *child, u64 clone_flags)
 {
 	struct perf_event_context *child_ctx, *parent_ctx;
 	struct perf_event_context *cloned_ctx;
@@ -13133,14 +13199,14 @@ static int perf_event_init_context(struc
 	unsigned long flags;
 	int ret = 0;
 
-	if (likely(!parent->perf_event_ctxp[ctxn]))
+	if (likely(!parent->perf_event_ctxp))
 		return 0;
 
 	/*
 	 * If the parent's context is a clone, pin it so it won't get
 	 * swapped under us.
 	 */
-	parent_ctx = perf_pin_task_context(parent, ctxn);
+	parent_ctx = perf_pin_task_context(parent);
 	if (!parent_ctx)
 		return 0;
 
@@ -13163,8 +13229,7 @@ static int perf_event_init_context(struc
 	 */
 	perf_event_groups_for_each(event, &parent_ctx->pinned_groups) {
 		ret = inherit_task_group(event, parent, parent_ctx,
-					 child, ctxn, clone_flags,
-					 &inherited_all);
+					 child, clone_flags, &inherited_all);
 		if (ret)
 			goto out_unlock;
 	}
@@ -13180,8 +13245,7 @@ static int perf_event_init_context(struc
 
 	perf_event_groups_for_each(event, &parent_ctx->flexible_groups) {
 		ret = inherit_task_group(event, parent, parent_ctx,
-					 child, ctxn, clone_flags,
-					 &inherited_all);
+					 child, clone_flags, &inherited_all);
 		if (ret)
 			goto out_unlock;
 	}
@@ -13189,7 +13253,7 @@ static int perf_event_init_context(struc
 	raw_spin_lock_irqsave(&parent_ctx->lock, flags);
 	parent_ctx->rotate_disable = 0;
 
-	child_ctx = child->perf_event_ctxp[ctxn];
+	child_ctx = child->perf_event_ctxp;
 
 	if (child_ctx && inherited_all) {
 		/*
@@ -13225,18 +13289,16 @@ static int perf_event_init_context(struc
  */
 int perf_event_init_task(struct task_struct *child, u64 clone_flags)
 {
-	int ctxn, ret;
+	int ret;
 
-	memset(child->perf_event_ctxp, 0, sizeof(child->perf_event_ctxp));
+	child->perf_event_ctxp = NULL;
 	mutex_init(&child->perf_event_mutex);
 	INIT_LIST_HEAD(&child->perf_event_list);
 
-	for_each_task_context_nr(ctxn) {
-		ret = perf_event_init_context(child, ctxn, clone_flags);
-		if (ret) {
-			perf_event_free_task(child);
-			return ret;
-		}
+	ret = perf_event_init_context(child, clone_flags);
+	if (ret) {
+		perf_event_free_task(child);
+		return ret;
 	}
 
 	return 0;
@@ -13245,6 +13307,7 @@ int perf_event_init_task(struct task_str
 static void __init perf_event_init_all_cpus(void)
 {
 	struct swevent_htable *swhash;
+	struct perf_cpu_context *cpuctx;
 	int cpu;
 
 	zalloc_cpumask_var(&perf_online_mask, GFP_KERNEL);
@@ -13252,7 +13315,6 @@ static void __init perf_event_init_all_c
 	for_each_possible_cpu(cpu) {
 		swhash = &per_cpu(swevent_htable, cpu);
 		mutex_init(&swhash->hlist_mutex);
-		INIT_LIST_HEAD(&per_cpu(active_ctx_list, cpu));
 
 		INIT_LIST_HEAD(&per_cpu(pmu_sb_events.list, cpu));
 		raw_spin_lock_init(&per_cpu(pmu_sb_events.lock, cpu));
@@ -13261,6 +13323,14 @@ static void __init perf_event_init_all_c
 		INIT_LIST_HEAD(&per_cpu(cgrp_cpuctx_list, cpu));
 #endif
 		INIT_LIST_HEAD(&per_cpu(sched_cb_list, cpu));
+
+		cpuctx = per_cpu_ptr(&cpu_context, cpu);
+		__perf_event_init_context(&cpuctx->ctx);
+		lockdep_set_class(&cpuctx->ctx.mutex, &cpuctx_mutex);
+		lockdep_set_class(&cpuctx->ctx.lock, &cpuctx_lock);
+		cpuctx->online = cpumask_test_cpu(cpu, perf_online_mask);
+		cpuctx->heap_size = ARRAY_SIZE(cpuctx->heap_default);
+		cpuctx->heap = cpuctx->heap_default;
 	}
 }
 
@@ -13282,12 +13352,12 @@ static void perf_swevent_init_cpu(unsign
 #if defined CONFIG_HOTPLUG_CPU || defined CONFIG_KEXEC_CORE
 static void __perf_event_exit_context(void *__info)
 {
+	struct perf_cpu_context *cpuctx = this_cpu_ptr(&cpu_context);
 	struct perf_event_context *ctx = __info;
-	struct perf_cpu_context *cpuctx = __get_cpu_context(ctx);
 	struct perf_event *event;
 
 	raw_spin_lock(&ctx->lock);
-	ctx_sched_out(ctx, cpuctx, EVENT_TIME);
+	ctx_sched_out(ctx, EVENT_TIME);
 	list_for_each_entry(event, &ctx->event_list, event_entry)
 		__perf_remove_from_context(event, cpuctx, ctx, (void *)DETACH_GROUP);
 	raw_spin_unlock(&ctx->lock);
@@ -13297,18 +13367,16 @@ static void perf_event_exit_cpu_context(
 {
 	struct perf_cpu_context *cpuctx;
 	struct perf_event_context *ctx;
-	struct pmu *pmu;
 
+	// XXX simplify cpuctx->online
 	mutex_lock(&pmus_lock);
-	list_for_each_entry(pmu, &pmus, entry) {
-		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
-		ctx = &cpuctx->ctx;
+	cpuctx = per_cpu_ptr(&cpu_context, cpu);
+	ctx = &cpuctx->ctx;
 
-		mutex_lock(&ctx->mutex);
-		smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1);
-		cpuctx->online = 0;
-		mutex_unlock(&ctx->mutex);
-	}
+	mutex_lock(&ctx->mutex);
+	smp_call_function_single(cpu, __perf_event_exit_context, ctx, 1);
+	cpuctx->online = 0;
+	mutex_unlock(&ctx->mutex);
 	cpumask_clear_cpu(cpu, perf_online_mask);
 	mutex_unlock(&pmus_lock);
 }
@@ -13322,20 +13390,17 @@ int perf_event_init_cpu(unsigned int cpu
 {
 	struct perf_cpu_context *cpuctx;
 	struct perf_event_context *ctx;
-	struct pmu *pmu;
 
 	perf_swevent_init_cpu(cpu);
 
 	mutex_lock(&pmus_lock);
 	cpumask_set_cpu(cpu, perf_online_mask);
-	list_for_each_entry(pmu, &pmus, entry) {
-		cpuctx = per_cpu_ptr(pmu->pmu_cpu_context, cpu);
-		ctx = &cpuctx->ctx;
+	cpuctx = per_cpu_ptr(&cpu_context, cpu);
+	ctx = &cpuctx->ctx;
 
-		mutex_lock(&ctx->mutex);
-		cpuctx->online = 1;
-		mutex_unlock(&ctx->mutex);
-	}
+	mutex_lock(&ctx->mutex);
+	cpuctx->online = 1;
+	mutex_unlock(&ctx->mutex);
 	mutex_unlock(&pmus_lock);
 
 	return 0;