Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 2525db04 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/powernv: Simplify lazy IRQ handling in CPU offline 



Rather than concern ourselves with any soft-mask logic in the CPU
hotplug handler, just hard disable interrupts. This ensures there
are no lazy-irqs pending, which means we can call directly to idle
instruction in order to sleep.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 2201f994

arch/powerpc/platforms/powernv/idle.c

+15 −8
Original line number Diff line number Diff line
@@ -352,25 +352,31 @@ void power9_idle(void) 
/*

 * pnv_cpu_offline: A function that puts the CPU into the deepest

 * available platform idle state on a CPU-Offline.

 * interrupts hard disabled and no lazy irq pending.

 */

unsigned long pnv_cpu_offline(unsigned int cpu)

{

	unsigned long srr1;



	u32 idle_states = pnv_get_supported_cpuidle_states();



	ppc64_runlatch_off();



	if (cpu_has_feature(CPU_FTR_ARCH_300) && deepest_stop_found) {

		srr1 = __power9_idle_type(pnv_deepest_stop_psscr_val,

					pnv_deepest_stop_psscr_mask);

		unsigned long psscr;



		psscr = mfspr(SPRN_PSSCR);

		psscr = (psscr & ~pnv_deepest_stop_psscr_mask) |

						pnv_deepest_stop_psscr_val;

		srr1 = power9_idle_stop(psscr);



	} else if (idle_states & OPAL_PM_WINKLE_ENABLED) {

		srr1 = __power7_idle_type(PNV_THREAD_WINKLE);

		srr1 = power7_idle_insn(PNV_THREAD_WINKLE);

	} else if ((idle_states & OPAL_PM_SLEEP_ENABLED) ||

		   (idle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {

		srr1 = __power7_idle_type(PNV_THREAD_SLEEP);

		srr1 = power7_idle_insn(PNV_THREAD_SLEEP);

	} else if (idle_states & OPAL_PM_NAP_ENABLED) {

		srr1 = __power7_idle_type(PNV_THREAD_NAP);

		srr1 = power7_idle_insn(PNV_THREAD_NAP);

	} else {

		ppc64_runlatch_off();

		/* This is the fallback method. We emulate snooze */

		while (!generic_check_cpu_restart(cpu)) {

			HMT_low();
@@ -378,9 +384,10 @@ unsigned long pnv_cpu_offline(unsigned int cpu) 
		}

		srr1 = 0;

		HMT_medium();

		ppc64_runlatch_on();

	}



	ppc64_runlatch_on();



	return srr1;

}

#endif

arch/powerpc/platforms/powernv/smp.c

+14 −15
Original line number Diff line number Diff line
@@ -144,7 +144,14 @@ static void pnv_smp_cpu_kill_self(void) 
	unsigned long srr1, wmask;



	/* Standard hot unplug procedure */

	local_irq_disable();

	/*

	 * This hard disables local interurpts, ensuring we have no lazy

	 * irqs pending.

	 */

	WARN_ON(irqs_disabled());

	hard_irq_disable();

	WARN_ON(lazy_irq_pending());



	idle_task_exit();

	current->active_mm = NULL; /* for sanity */

	cpu = smp_processor_id();
@@ -162,16 +169,6 @@ static void pnv_smp_cpu_kill_self(void) 
	 */

	mtspr(SPRN_LPCR, mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1);



	/*

	 * Hard-disable interrupts, and then clear irq_happened flags

	 * that we can safely ignore while off-line, since they

	 * are for things for which we do no processing when off-line

	 * (or in the case of HMI, all the processing we need to do

	 * is done in lower-level real-mode code).

	 */

	hard_irq_disable();

	local_paca->irq_happened &= ~(PACA_IRQ_DEC | PACA_IRQ_HMI);



	while (!generic_check_cpu_restart(cpu)) {

		/*

		 * Clear IPI flag, since we don't handle IPIs while
@@ -184,6 +181,8 @@ static void pnv_smp_cpu_kill_self(void) 


		srr1 = pnv_cpu_offline(cpu);



		WARN_ON(lazy_irq_pending());



		/*

		 * If the SRR1 value indicates that we woke up due to

		 * an external interrupt, then clear the interrupt.
@@ -196,8 +195,7 @@ static void pnv_smp_cpu_kill_self(void) 
		 * contains 0.

		 */

		if (((srr1 & wmask) == SRR1_WAKEEE) ||

		    ((srr1 & wmask) == SRR1_WAKEHVI) ||

		    (local_paca->irq_happened & PACA_IRQ_EE)) {

		    ((srr1 & wmask) == SRR1_WAKEHVI)) {

			if (cpu_has_feature(CPU_FTR_ARCH_300)) {

				if (xive_enabled())

					xive_flush_interrupt();
@@ -209,14 +207,15 @@ static void pnv_smp_cpu_kill_self(void) 
			unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);

			asm volatile(PPC_MSGCLR(%0) : : "r" (msg));

		}

		local_paca->irq_happened &= ~(PACA_IRQ_EE | PACA_IRQ_DBELL);

		smp_mb();



		if (cpu_core_split_required())

			continue;



		if (srr1 && !generic_check_cpu_restart(cpu))

			DBG("CPU%d Unexpected exit while offline !\n", cpu);

			DBG("CPU%d Unexpected exit while offline srr1=%lx!\n",

					cpu, srr1);



	}



	/* Re-enable decrementer interrupts */