powerpc/powernv: Fix CPU idle to be called with IRQs disabled

BugLink: https://bugs.launchpad.net/bugs/1851550
[ Upstream commit 7d6475051fb3d9339c5c760ed9883bc0a9048b21 ]

Commit e78a7614f3876 ("idle: Prevent late-arriving interrupts from
disrupting offline") changes arch_cpu_idle_dead to be called with
interrupts disabled, which triggers the WARN in pnv_smp_cpu_kill_self.

Fix this by fixing up irq_happened after hard disabling, rather than
requiring there are no pending interrupts, similarly to what was done
done until commit 2525db04d1cc5 ("powerpc/powernv: Simplify lazy IRQ
handling in CPU offline").

Fixes: e78a7614f3876 ("idle: Prevent late-arriving interrupts from disrupting offline")
Reported-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Add unexpected_mask rather than checking for known bad values,
      change the WARN_ON() to a WARN_ON_ONCE()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20191022115814.22456-1-npiggin@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/arch/powerpc/platforms/powernv/smp.c b/arch/powerpc/platforms/powernv/smp.c
index 94cd96b9b7bbc5d9b224bb9c9b9f02b9516ebfeb..001dfac8354a8b1b7fa51f0dd7d6cbe2d3fd5f8d 100644 (file)
--- a/arch/powerpc/platforms/powernv/smp.c
+++ b/arch/powerpc/platforms/powernv/smp.c
@@ -146,20 +146,25 @@ static int pnv_smp_cpu_disable(void)
        return 0;
 }
 
+static void pnv_flush_interrupts(void)
+{
+       if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+               if (xive_enabled())
+                       xive_flush_interrupt();
+               else
+                       icp_opal_flush_interrupt();
+       } else {
+               icp_native_flush_interrupt();
+       }
+}
+
 static void pnv_smp_cpu_kill_self(void)
 {
+       unsigned long srr1, unexpected_mask, wmask;
        unsigned int cpu;
-       unsigned long srr1, wmask;
        u64 lpcr_val;
 
        /* Standard hot unplug procedure */
-       /*
-        * 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 */
@@ -172,6 +177,27 @@ static void pnv_smp_cpu_kill_self(void)
        if (cpu_has_feature(CPU_FTR_ARCH_207S))
                wmask = SRR1_WAKEMASK_P8;
 
+       /*
+        * This turns the irq soft-disabled state we're called with, into a
+        * hard-disabled state with pending irq_happened interrupts cleared.
+        *
+        * PACA_IRQ_DEC   - Decrementer should be ignored.
+        * PACA_IRQ_HMI   - Can be ignored, processing is done in real mode.
+        * PACA_IRQ_DBELL, EE, PMI - Unexpected.
+        */
+       hard_irq_disable();
+       if (generic_check_cpu_restart(cpu))
+               goto out;
+
+       unexpected_mask = ~(PACA_IRQ_DEC | PACA_IRQ_HMI | PACA_IRQ_HARD_DIS);
+       if (local_paca->irq_happened & unexpected_mask) {
+               if (local_paca->irq_happened & PACA_IRQ_EE)
+                       pnv_flush_interrupts();
+               DBG("CPU%d Unexpected exit while offline irq_happened=%lx!\n",
+                               cpu, local_paca->irq_happened);
+       }
+       local_paca->irq_happened = PACA_IRQ_HARD_DIS;
+
        /*
         * We don't want to take decrementer interrupts while we are
         * offline, so clear LPCR:PECE1. We keep PECE2 (and
@@ -197,6 +223,7 @@ static void pnv_smp_cpu_kill_self(void)
 
                srr1 = pnv_cpu_offline(cpu);
 
+               WARN_ON_ONCE(!irqs_disabled());
                WARN_ON(lazy_irq_pending());
 
                /*
@@ -212,13 +239,7 @@ static void pnv_smp_cpu_kill_self(void)
                 */
                if (((srr1 & wmask) == SRR1_WAKEEE) ||
                    ((srr1 & wmask) == SRR1_WAKEHVI)) {
-                       if (cpu_has_feature(CPU_FTR_ARCH_300)) {
-                               if (xive_enabled())
-                                       xive_flush_interrupt();
-                               else
-                                       icp_opal_flush_interrupt();
-                       } else
-                               icp_native_flush_interrupt();
+                       pnv_flush_interrupts();
                } else if ((srr1 & wmask) == SRR1_WAKEHDBELL) {
                        unsigned long msg = PPC_DBELL_TYPE(PPC_DBELL_SERVER);
                        asm volatile(PPC_MSGCLR(%0) : : "r" (msg));
@@ -266,7 +287,7 @@ static void pnv_smp_cpu_kill_self(void)
         */
        lpcr_val = mfspr(SPRN_LPCR) | (u64)LPCR_PECE1;
        pnv_program_cpu_hotplug_lpcr(cpu, lpcr_val);
-
+out:
        DBG("CPU%d coming online...\n", cpu);
 }