linux-kernel - [RFC][PATCH 2/4] acpi: Use CPUIDLE_FLAG_TLB

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Date:   Tue, 15 Sep 2020 12:31:59 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     rjw@...ysocki.net, bp@...en8.de
Cc:     x86@...nel.org, tony.luck@...el.com, lenb@...nel.org,
        daniel.lezcano@...aro.org, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, linux-pm@...r.kernel.org,
        ulf.hansson@...aro.org, paulmck@...nel.org, tglx@...utronix.de,
        naresh.kamboju@...aro.org, peterz@...radead.org
Subject: [RFC][PATCH 2/4] acpi: Use CPUIDLE_FLAG_TLB_FLUSHED

Make acpi_processor_idle() use the generic TLB flushing code.
This again removes RCU usage after rcu_idle_enter().

(XXX make every C3 invalidate TLBs, not just C3-BM)

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 arch/ia64/include/asm/acpi.h  |    2 --
 arch/x86/include/asm/acpi.h   |    2 --
 drivers/acpi/processor_idle.c |   10 +++++-----
 3 files changed, 5 insertions(+), 9 deletions(-)

--- a/arch/ia64/include/asm/acpi.h
+++ b/arch/ia64/include/asm/acpi.h
@@ -74,8 +74,6 @@ static inline void arch_acpi_set_pdc_bit
 	buf[2] |= ACPI_PDC_EST_CAPABILITY_SMP;
 }
 
-#define acpi_unlazy_tlb(x)
-
 #ifdef CONFIG_ACPI_NUMA
 extern cpumask_t early_cpu_possible_map;
 #define for_each_possible_early_cpu(cpu)  \
--- a/arch/x86/include/asm/acpi.h
+++ b/arch/x86/include/asm/acpi.h
@@ -159,8 +159,6 @@ static inline u64 x86_default_get_root_p
 extern int x86_acpi_numa_init(void);
 #endif /* CONFIG_ACPI_NUMA */
 
-#define acpi_unlazy_tlb(x)	leave_mm(x)
-
 #ifdef CONFIG_ACPI_APEI
 static inline pgprot_t arch_apei_get_mem_attribute(phys_addr_t addr)
 {
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -565,8 +565,6 @@ static DEFINE_RAW_SPINLOCK(c3_lock);
 static void acpi_idle_enter_bm(struct acpi_processor *pr,
 			       struct acpi_processor_cx *cx)
 {
-	acpi_unlazy_tlb(smp_processor_id());
-
 	/*
 	 * disable bus master
 	 * bm_check implies we need ARB_DIS
@@ -666,6 +664,7 @@ static int acpi_processor_setup_cpuidle_
 		max_cstate = 1;
 
 	for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++) {
+		state = &acpi_idle_driver.states[count];
 		cx = &pr->power.states[i];
 
 		if (!cx->valid)
@@ -673,10 +672,11 @@ static int acpi_processor_setup_cpuidle_
 
 		per_cpu(acpi_cstate[count], dev->cpu) = cx;
 
-		if (lapic_timer_needs_broadcast(pr, cx)) {
-			state = &acpi_idle_driver.states[count];
+		if (lapic_timer_needs_broadcast(pr, cx))
 			state->flags |= CPUIDLE_FLAG_TIMER_STOP;
-		}
+
+		if (cx->type == ACPI_STATE_C3)
+			state->flags |= CPUIDLE_FLAG_TLB_FLUSHED;
 
 		count++;
 		if (count == CPUIDLE_STATE_MAX)