cpuidle: Make CPUIDLE_FLAG_TLB_FLUSHED generic

This allows moving the leave_mm() call into generic code before
rcu_idle_enter(). Gets rid of more trace_*_rcuidle() users.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Marco Elver <elver@google.com>
Link: https://lkml.kernel.org/r/20200821085348.369441600@infradead.org

arch/x86/include/asm/mmu.h

@@ -59,5 +59,6 @@ typedef struct {
 	}
 
 void leave_mm(int cpu);
+#define leave_mm leave_mm
 
 #endif /* _ASM_X86_MMU_H */

arch/x86/mm/tlb.c

@@ -555,21 +555,12 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
 		this_cpu_write(cpu_tlbstate.ctxs[new_asid].tlb_gen, next_tlb_gen);
 		load_new_mm_cr3(next->pgd, new_asid, true);
 
-		/*
+		trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
-		 * NB: This gets called via leave_mm() in the idle path
-		 * where RCU functions differently.  Tracing normally
-		 * uses RCU, so we need to use the _rcuidle variant.
-		 *
-		 * (There is no good reason for this.  The idle code should
-		 *  be rearranged to call this before rcu_idle_enter().)
-		 */
-		trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL);
 	} else {
 		/* The new ASID is already up to date. */
 		load_new_mm_cr3(next->pgd, new_asid, false);
 
-		/* See above wrt _rcuidle. */
+		trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, 0);
-		trace_tlb_flush_rcuidle(TLB_FLUSH_ON_TASK_SWITCH, 0);
 	}
 
 	/* Make sure we write CR3 before loaded_mm. */

drivers/cpuidle/cpuidle.c

@@ -22,6 +22,7 @@
 #include <linux/module.h>
 #include <linux/suspend.h>
 #include <linux/tick.h>
+#include <linux/mmu_context.h>
 #include <trace/events/power.h>
 
 #include "cpuidle.h"
@@ -228,6 +229,9 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
 		broadcast = false;
 	}
 
+	if (target_state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
+		leave_mm(dev->cpu);
+
 	/* Take note of the planned idle state. */
 	sched_idle_set_state(target_state);
 

drivers/idle/intel_idle.c

@@ -89,14 +89,6 @@ static unsigned int mwait_substates __initdata;
  */
 #define CPUIDLE_FLAG_ALWAYS_ENABLE	BIT(15)
 
-/*
- * Set this flag for states where the HW flushes the TLB for us
- * and so we don't need cross-calls to keep it consistent.
- * If this flag is set, SW flushes the TLB, so even if the
- * HW doesn't do the flushing, this flag is safe to use.
- */
-#define CPUIDLE_FLAG_TLB_FLUSHED	BIT(16)
-
 /*
  * MWAIT takes an 8-bit "hint" in EAX "suggesting"
  * the C-state (top nibble) and sub-state (bottom nibble)
@@ -131,14 +123,6 @@ static __cpuidle int intel_idle(struct cpuidle_device *dev,
 	unsigned long eax = flg2MWAIT(state->flags);
 	unsigned long ecx = 1; /* break on interrupt flag */
 	bool tick;
-	int cpu = smp_processor_id();
-
-	/*
-	 * leave_mm() to avoid costly and often unnecessary wakeups
-	 * for flushing the user TLB's associated with the active mm.
-	 */
-	if (state->flags & CPUIDLE_FLAG_TLB_FLUSHED)
-		leave_mm(cpu);
 
 	if (!static_cpu_has(X86_FEATURE_ARAT)) {
 		/*

include/linux/cpuidle.h

@@ -81,6 +81,7 @@ struct cpuidle_state {
 #define CPUIDLE_FLAG_TIMER_STOP 	BIT(2) /* timer is stopped on this state */
 #define CPUIDLE_FLAG_UNUSABLE		BIT(3) /* avoid using this state */
 #define CPUIDLE_FLAG_OFF		BIT(4) /* disable this state by default */
+#define CPUIDLE_FLAG_TLB_FLUSHED	BIT(5) /* idle-state flushes TLBs */
 
 struct cpuidle_device_kobj;
 struct cpuidle_state_kobj;

include/linux/mmu_context.h

@@ -3,10 +3,15 @@
 #define _LINUX_MMU_CONTEXT_H
 
 #include <asm/mmu_context.h>
+#include <asm/mmu.h>
 
 /* Architectures that care about IRQ state in switch_mm can override this. */
 #ifndef switch_mm_irqs_off
 # define switch_mm_irqs_off switch_mm
 #endif
 
+#ifndef leave_mm
+static inline void leave_mm(int cpu) { }
+#endif
+
 #endif