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: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index f875879ff1eb32b882d1a5c755a4a54803d766c6..f188d84d9c593660e9ed6fe5ae2ab492667231b7 100644 (file)
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -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

diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index f8752795decf3eaf564de02bfcef666bbaad1316..c04c87adad94561ad7ef8c6170c1165f08e5e5b2 100644 (file)
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -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 */