From ccbb37970b3270861b379906a11b534a14e9631d Mon Sep 17 00:00:00 2001
From: attilio <attilio@FreeBSD.org>
Date: Fri, 20 May 2011 14:53:16 +0000
Subject: Reintroduce the lazypmap infrastructure and convert it to using
 cpuset_t.

Requested by:	alc
---
 sys/i386/xen/pmap.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)

(limited to 'sys/i386/xen/pmap.c')

diff --git a/sys/i386/xen/pmap.c b/sys/i386/xen/pmap.c
index 74ace61..1149b6f 100644
--- a/sys/i386/xen/pmap.c
+++ b/sys/i386/xen/pmap.c
@@ -1683,6 +1683,104 @@ retry:
 * Pmap allocation/deallocation routines.
  ***************************************************/
 
+#ifdef SMP
+/*
+ * Deal with a SMP shootdown of other users of the pmap that we are
+ * trying to dispose of.  This can be a bit hairy.
+ */
+static cpuset_t *lazymask;
+static u_int lazyptd;
+static volatile u_int lazywait;
+
+void pmap_lazyfix_action(void);
+
+void
+pmap_lazyfix_action(void)
+{
+
+#ifdef COUNT_IPIS
+	(*ipi_lazypmap_counts[PCPU_GET(cpuid)])++;
+#endif
+	if (rcr3() == lazyptd)
+		load_cr3(PCPU_GET(curpcb)->pcb_cr3);
+	CPU_CLR_ATOMIC(PCPU_GET(cpuid), lazymask);
+	atomic_store_rel_int(&lazywait, 1);
+}
+
+static void
+pmap_lazyfix_self(cpuset_t mymask)
+{
+
+	if (rcr3() == lazyptd)
+		load_cr3(PCPU_GET(curpcb)->pcb_cr3);
+	CPU_NAND_ATOMIC(lazymask, &mymask);
+}
+
+
+static void
+pmap_lazyfix(pmap_t pmap)
+{
+	cpuset_t mymask, mask;
+	u_int spins;
+	int lsb;
+
+	mask = pmap->pm_active;
+	while (!CPU_EMPTY(&mask)) {
+		spins = 50000000;
+
+		/* Find least significant set bit. */
+		lsb = cpusetobj_ffs(&mask);
+		lsb--;
+		CPU_SETOF(lsb, &mask);
+		mtx_lock_spin(&smp_ipi_mtx);
+#ifdef PAE
+		lazyptd = vtophys(pmap->pm_pdpt);
+#else
+		lazyptd = vtophys(pmap->pm_pdir);
+#endif
+		mymask = PCPU_GET(cpumask);
+		if (mask == mymask) {
+			lazymask = &pmap->pm_active;
+			pmap_lazyfix_self(mymask);
+		} else {
+			atomic_store_rel_int((u_int *)&lazymask,
+			    (u_int)&pmap->pm_active);
+			atomic_store_rel_int(&lazywait, 0);
+			ipi_selected(mask, IPI_LAZYPMAP);
+			while (lazywait == 0) {
+				ia32_pause();
+				if (--spins == 0)
+					break;
+			}
+		}
+		mtx_unlock_spin(&smp_ipi_mtx);
+		if (spins == 0)
+			printf("pmap_lazyfix: spun for 50000000\n");
+		mask = pmap->pm_active;
+	}
+}
+
+#else	/* SMP */
+
+/*
+ * Cleaning up on uniprocessor is easy.  For various reasons, we're
+ * unlikely to have to even execute this code, including the fact
+ * that the cleanup is deferred until the parent does a wait(2), which
+ * means that another userland process has run.
+ */
+static void
+pmap_lazyfix(pmap_t pmap)
+{
+	u_int cr3;
+
+	cr3 = vtophys(pmap->pm_pdir);
+	if (cr3 == rcr3()) {
+		load_cr3(PCPU_GET(curpcb)->pcb_cr3);
+		CPU_CLR(PCPU_GET(cpuid), &pmap->pm_active);
+	}
+}
+#endif	/* SMP */
+
 /*
  * Release any resources held by the given physical map.
  * Called when a pmap initialized by pmap_pinit is being released.
@@ -1708,6 +1806,7 @@ pmap_release(pmap_t pmap)
 	mtx_lock(&createdelete_lock);
 #endif
 
+	pmap_lazyfix(pmap);
 	mtx_lock_spin(&allpmaps_lock);
 	LIST_REMOVE(pmap, pm_list);
 	mtx_unlock_spin(&allpmaps_lock);
-- 
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