[POWERPC] Update lmb data structures for hotplug memory add/remove

The powerpc kernel maintains information about logical memory blocks
in the lmb.memory structure, which is initialized and updated at boot
time, but not when memory is added or removed while the kernel is
running.

This adds a hotplug memory notifier which updates lmb.memory when
memory is added or removed.  This information is useful for eHEA
driver to find out the memory layout and holes.

NOTE: No special locking is needed for lmb_add() and lmb_remove().
Calls to these are serialized by caller. (pSeries_reconfig_chain).
Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/platforms/pseries/hotplug-memory.c

@@ -10,6 +10,7 @@
  */
 
 #include <linux/of.h>
+#include <linux/lmb.h>
 #include <asm/firmware.h>
 #include <asm/machdep.h>
 #include <asm/pSeries_reconfig.h>
@@ -57,6 +58,11 @@ static int pseries_remove_memory(struct device_node *np)
 	if (ret)
 		return ret;
 
+	/*
+	 * Update memory regions for memory remove
+	 */
+	lmb_remove(start_pfn << PAGE_SHIFT, regs[3]);
+
 	/*
 	 * Remove htab bolted mappings for this section of memory
 	 */
@@ -65,6 +71,41 @@ static int pseries_remove_memory(struct device_node *np)
 	return ret;
 }
 
+static int pseries_add_memory(struct device_node *np)
+{
+	const char *type;
+	const unsigned int *my_index;
+	const unsigned int *regs;
+	u64 start_pfn;
+	int ret = -EINVAL;
+
+	/*
+	 * Check to see if we are actually adding 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 added 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);
+
+	/*
+	 * Update memory region to represent the memory add
+	 */
+	lmb_add(start_pfn << PAGE_SHIFT, regs[3]);
+	return 0;
+}
+
 static int pseries_memory_notifier(struct notifier_block *nb,
 				unsigned long action, void *node)
 {
@@ -72,6 +113,8 @@ static int pseries_memory_notifier(struct notifier_block *nb,
 
 	switch (action) {
 	case PSERIES_RECONFIG_ADD:
+		if (pseries_add_memory(node))
+			err = NOTIFY_BAD;
 		break;
 	case PSERIES_RECONFIG_REMOVE:
 		if (pseries_remove_memory(node))

include/linux/lmb.h

@@ -40,7 +40,8 @@ extern struct lmb lmb;
 
 extern void __init lmb_init(void);
 extern void __init lmb_analyze(void);
-extern long __init lmb_add(u64 base, u64 size);
+extern long lmb_add(u64 base, u64 size);
+extern long lmb_remove(u64 base, u64 size);
 extern long __init lmb_reserve(u64 base, u64 size);
 extern u64 __init lmb_alloc_nid(u64 size, u64 align, int nid,
 				u64 (*nid_range)(u64, u64, int *));

lib/lmb.c

@@ -46,14 +46,13 @@ void lmb_dump_all(void)
 #endif /* DEBUG */
 }
 
-static unsigned long __init lmb_addrs_overlap(u64 base1, u64 size1,
-		u64 base2, u64 size2)
+static unsigned long lmb_addrs_overlap(u64 base1, u64 size1, u64 base2,
+					u64 size2)
 {
 	return ((base1 < (base2 + size2)) && (base2 < (base1 + size1)));
 }
 
-static long __init lmb_addrs_adjacent(u64 base1, u64 size1,
-		u64 base2, u64 size2)
+static long lmb_addrs_adjacent(u64 base1, u64 size1, u64 base2, u64 size2)
 {
 	if (base2 == base1 + size1)
 		return 1;
@@ -63,7 +62,7 @@ static long __init lmb_addrs_adjacent(u64 base1, u64 size1,
 	return 0;
 }
 
-static long __init lmb_regions_adjacent(struct lmb_region *rgn,
+static long lmb_regions_adjacent(struct lmb_region *rgn,
 		unsigned long r1, unsigned long r2)
 {
 	u64 base1 = rgn->region[r1].base;
@@ -74,7 +73,7 @@ static long __init lmb_regions_adjacent(struct lmb_region *rgn,
 	return lmb_addrs_adjacent(base1, size1, base2, size2);
 }
 
-static void __init lmb_remove_region(struct lmb_region *rgn, unsigned long r)
+static void lmb_remove_region(struct lmb_region *rgn, unsigned long r)
 {
 	unsigned long i;
 
@@ -86,7 +85,7 @@ static void __init lmb_remove_region(struct lmb_region *rgn, unsigned long r)
 }
 
 /* Assumption: base addr of region 1 < base addr of region 2 */
-static void __init lmb_coalesce_regions(struct lmb_region *rgn,
+static void lmb_coalesce_regions(struct lmb_region *rgn,
 		unsigned long r1, unsigned long r2)
 {
 	rgn->region[r1].size += rgn->region[r2].size;
@@ -118,7 +117,7 @@ void __init lmb_analyze(void)
 		lmb.memory.size += lmb.memory.region[i].size;
 }
 
-static long __init lmb_add_region(struct lmb_region *rgn, u64 base, u64 size)
+static long lmb_add_region(struct lmb_region *rgn, u64 base, u64 size)
 {
 	unsigned long coalesced = 0;
 	long adjacent, i;
@@ -182,7 +181,7 @@ static long __init lmb_add_region(struct lmb_region *rgn, u64 base, u64 size)
 	return 0;
 }
 
-long __init lmb_add(u64 base, u64 size)
+long lmb_add(u64 base, u64 size)
 {
 	struct lmb_region *_rgn = &lmb.memory;
 
@@ -194,6 +193,55 @@ long __init lmb_add(u64 base, u64 size)
 
 }
 
+long lmb_remove(u64 base, u64 size)
+{
+	struct lmb_region *rgn = &(lmb.memory);
+	u64 rgnbegin, rgnend;
+	u64 end = base + size;
+	int i;
+
+	rgnbegin = rgnend = 0; /* supress gcc warnings */
+
+	/* Find the region where (base, size) belongs to */
+	for (i=0; i < rgn->cnt; i++) {
+		rgnbegin = rgn->region[i].base;
+		rgnend = rgnbegin + rgn->region[i].size;
+
+		if ((rgnbegin <= base) && (end <= rgnend))
+			break;
+	}
+
+	/* Didn't find the region */
+	if (i == rgn->cnt)
+		return -1;
+
+	/* Check to see if we are removing entire region */
+	if ((rgnbegin == base) && (rgnend == end)) {
+		lmb_remove_region(rgn, i);
+		return 0;
+	}
+
+	/* Check to see if region is matching at the front */
+	if (rgnbegin == base) {
+		rgn->region[i].base = end;
+		rgn->region[i].size -= size;
+		return 0;
+	}
+
+	/* Check to see if the region is matching at the end */
+	if (rgnend == end) {
+		rgn->region[i].size -= size;
+		return 0;
+	}
+
+	/*
+	 * We need to split the entry -  adjust the current one to the
+	 * beginging of the hole and add the region after hole.
+	 */
+	rgn->region[i].size = base - rgn->region[i].base;
+	return lmb_add_region(rgn, end, rgnend - end);
+}
+
 long __init lmb_reserve(u64 base, u64 size)
 {
 	struct lmb_region *_rgn = &lmb.reserved;