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Date:      Mon, 12 May 2014 02:56:27 +0000 (UTC)
From:      Nathan Whitehorn <nwhitehorn@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r265900 - in head/sys/powerpc: powerpc ps3
Message-ID:  <201405120256.s4C2uREc052219@svn.freebsd.org>
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Author: nwhitehorn
Date: Mon May 12 02:56:27 2014
New Revision: 265900
URL: http://svnweb.freebsd.org/changeset/base/265900

Log:
  Repair some races in IPI handling:
  1. Make sure IPI mask is set before sending the IPI
  2. Operate atomically on PS3 PIC outstanding interrupt list
  3. Make sure IPIs are EOI'ed before, not after, processing. Without this,
     a second IPI could be sent partway through processing the first one,
     get erroneously acknowledge by the EOI to the first, and be lost. In
     particular in the case of smp_rendezvous(), this can be fatal.
  
  In combination, this makes the PS3 boot SMP again. It probably also fixes
  some latent bugs elsewhere.
  
  MFC after:	2 weeks

Modified:
  head/sys/powerpc/powerpc/intr_machdep.c
  head/sys/powerpc/powerpc/mp_machdep.c
  head/sys/powerpc/ps3/ps3pic.c

Modified: head/sys/powerpc/powerpc/intr_machdep.c
==============================================================================
--- head/sys/powerpc/powerpc/intr_machdep.c	Mon May 12 01:47:45 2014	(r265899)
+++ head/sys/powerpc/powerpc/intr_machdep.c	Mon May 12 02:56:27 2014	(r265900)
@@ -103,6 +103,7 @@ struct powerpc_intr {
 	enum intr_trigger trig;
 	enum intr_polarity pol;
 	int	fwcode;
+	int	ipi;
 };
 
 struct pic {
@@ -203,6 +204,8 @@ intr_lookup(u_int irq)
 	i->irq = irq;
 	i->pic = NULL;
 	i->vector = -1;
+	i->fwcode = 0;
+	i->ipi = 0;
 
 #ifdef SMP
 	i->cpu = all_cpus;
@@ -415,6 +418,15 @@ powerpc_enable_intr(void)
 				printf("unable to setup IPI handler\n");
 				return (error);
 			}
+
+			/*
+			 * Some subterfuge: disable late EOI and mark this
+			 * as an IPI to the dispatch layer.
+			 */
+			i = intr_lookup(MAP_IRQ(piclist[n].node,
+			    piclist[n].irqs));
+			i->event->ie_post_filter = NULL;
+			i->ipi = 1;
 		}
 	}
 #endif
@@ -568,6 +580,13 @@ powerpc_dispatch_intr(u_int vector, stru
 	ie = i->event;
 	KASSERT(ie != NULL, ("%s: interrupt without an event", __func__));
 
+	/*
+	 * IPIs are magical and need to be EOI'ed before filtering.
+	 * This prevents races in IPI handling.
+	 */
+	if (i->ipi)
+		PIC_EOI(i->pic, i->intline);
+
 	if (intr_event_handle(ie, tf) != 0) {
 		goto stray;
 	}

Modified: head/sys/powerpc/powerpc/mp_machdep.c
==============================================================================
--- head/sys/powerpc/powerpc/mp_machdep.c	Mon May 12 01:47:45 2014	(r265899)
+++ head/sys/powerpc/powerpc/mp_machdep.c	Mon May 12 02:56:27 2014	(r265900)
@@ -336,6 +336,7 @@ ipi_send(struct pcpu *pc, int ipi)
 	    pc, pc->pc_cpuid, ipi);
 
 	atomic_set_32(&pc->pc_ipimask, (1 << ipi));
+	powerpc_sync();
 	PIC_IPI(root_pic, pc->pc_cpuid);
 
 	CTR1(KTR_SMP, "%s: sent", __func__);

Modified: head/sys/powerpc/ps3/ps3pic.c
==============================================================================
--- head/sys/powerpc/ps3/ps3pic.c	Mon May 12 01:47:45 2014	(r265899)
+++ head/sys/powerpc/ps3/ps3pic.c	Mon May 12 02:56:27 2014	(r265900)
@@ -166,12 +166,13 @@ ps3pic_dispatch(device_t dev, struct tra
 	sc = device_get_softc(dev);
 
 	if (PCPU_GET(cpuid) == 0) {
-		bitmap = sc->bitmap_thread0[0];
+		bitmap = atomic_readandclear_64(&sc->bitmap_thread0[0]);
 		mask = sc->mask_thread0[0];
 	} else {
-		bitmap = sc->bitmap_thread1[0];
+		bitmap = atomic_readandclear_64(&sc->bitmap_thread1[0]);
 		mask = sc->mask_thread1[0];
 	}
+	powerpc_sync();
 
 	while ((irq = ffsl(bitmap & mask) - 1) != -1) {
 		bitmap &= ~(1UL << irq);

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