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Subject[PATCH 3/5] [PPC] hotplug memory notifications for ppc
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Hotplug memory notifier for ppc64. This gets invoked by writing
the device-node that needs to be removed to /proc/ppc64/ofdt.
We need to adjust the sections and remove sysfs entries by
calling __remove_pages(). Then call arch specific code to
get rid of htab mappings for the section of memory.

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Reviewed-by: Michael Ellerman <michael@ellerman.id.au>
---
arch/powerpc/platforms/pseries/Makefile | 1
arch/powerpc/platforms/pseries/hotplug-memory.c | 98 ++++++++++++++++++++++++
2 files changed, 99 insertions(+)

Index: linux-2.6.25-rc2/arch/powerpc/platforms/pseries/hotplug-memory.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.25-rc2/arch/powerpc/platforms/pseries/hotplug-memory.c 2008-02-29 09:25:14.000000000 -0800
@@ -0,0 +1,98 @@
+/*
+ * pseries Memory Hotplug infrastructure.
+ *
+ * Copyright (C) 2008 Badari Pulavarty, IBM Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/of.h>
+#include <asm/firmware.h>
+#include <asm/machdep.h>
+#include <asm/pSeries_reconfig.h>
+
+static int pseries_remove_memory(struct device_node *np)
+{
+ const char *type;
+ const unsigned int *my_index;
+ const unsigned int *regs;
+ u64 start_pfn, start;
+ struct zone *zone;
+ int ret = -EINVAL;
+
+ /*
+ * Check to see if we are actually removing memory
+ */
+ type = of_get_property(np, "device_type", NULL);
+ if (type == NULL || strcmp(type, "memory") != 0)
+ return 0;
+
+ /*
+ * Find the memory index and size of the removing section
+ */
+ my_index = of_get_property(np, "ibm,my-drc-index", NULL);
+ if (!my_index)
+ return ret;
+
+ regs = of_get_property(np, "reg", NULL);
+ if (!regs)
+ return ret;
+
+ start_pfn = section_nr_to_pfn(*my_index & 0xffff);
+ zone = page_zone(pfn_to_page(start_pfn));
+
+ /*
+ * Remove section mappings and sysfs entries for the
+ * section of the memory we are removing.
+ *
+ * NOTE: Ideally, this should be done in generic code like
+ * remove_memory(). But remove_memory() gets called by writing
+ * to sysfs "state" file and we can't remove sysfs entries
+ * while writing to it. So we have to defer it to here.
+ */
+ ret = __remove_pages(zone, start_pfn, regs[3] >> PAGE_SHIFT);
+ if (ret)
+ return ret;
+
+ /*
+ * Remove htab bolted mappings for this section of memory
+ */
+ start = (unsigned long)__va(start_pfn << PAGE_SHIFT);
+ ret = remove_section_mapping(start, start + regs[3]);
+ return ret;
+}
+
+static int pseries_memory_notifier(struct notifier_block *nb,
+ unsigned long action, void *node)
+{
+ int err = NOTIFY_OK;
+
+ switch (action) {
+ case PSERIES_RECONFIG_ADD:
+ break;
+ case PSERIES_RECONFIG_REMOVE:
+ if (pseries_remove_memory(node))
+ err = NOTIFY_BAD;
+ break;
+ default:
+ err = NOTIFY_DONE;
+ break;
+ }
+ return err;
+}
+
+static struct notifier_block pseries_mem_nb = {
+ .notifier_call = pseries_memory_notifier,
+};
+
+static int __init pseries_memory_hotplug_init(void)
+{
+ if (firmware_has_feature(FW_FEATURE_LPAR))
+ pSeries_reconfig_notifier_register(&pseries_mem_nb);
+
+ return 0;
+}
+machine_device_initcall(pseries, pseries_memory_hotplug_init);
Index: linux-2.6.25-rc2/arch/powerpc/platforms/pseries/Makefile
===================================================================
--- linux-2.6.25-rc2.orig/arch/powerpc/platforms/pseries/Makefile 2008-02-28 08:15:53.000000000 -0800
+++ linux-2.6.25-rc2/arch/powerpc/platforms/pseries/Makefile 2008-02-28 08:17:57.000000000 -0800
@@ -14,6 +14,7 @@ obj-$(CONFIG_PCI) += pci.o pci_dlpar.o
obj-$(CONFIG_PCI_MSI) += msi.o

obj-$(CONFIG_HOTPLUG_CPU) += hotplug-cpu.o
+obj-$(CONFIG_MEMORY_HOTPLUG) += hotplug-memory.o

obj-$(CONFIG_HVC_CONSOLE) += hvconsole.o
obj-$(CONFIG_HVCS) += hvcserver.o



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