[POWERPC] Hotplug memory remove notifications for powerpc

Hotplug memory remove notifier for 64-bit powerpc.  This gets invoked
by writing to /proc/ppc64/ofdt the string "remove_node " followed by
the firmware device tree pathname of the node that needs to be removed.

In response, this adjusts the sections and removes sysfs entries by
calling __remove_pages().  Then it calls arch-specific code to get rid
of the hardware MMU mappings for the section of memory.

Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Reviewed-by: Michael Ellerman <michael@ellerman.id.au>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index bd2593e..554c6e4 100644 (file)
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -18,6 +18,7 @@ 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

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
new file mode 100644 (file)
index 0000000..2d3e9a4
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -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);