[Skiboot] [PATCH 1/3] mem_region: Add reserved regions after memory init

[Oliver O'Halloran]

When a new memory region is added (e.g for memory reserved by firmware)
the list of existing memory regions is iterated through and a cut-out is
made in any existing region that overlaps with the new one. Prior to the
HDAT reservations being made the region init process was always:

1) Create regions from the memory@<addr> DT nodes. (mostly large)
2) Create reserved regions from the device-tree. (mostly small)

When adding new regions we have assume that the new region will only
every intersect with at most one existing region, which it will split.
Adding reservations inside the HDAT parser breaks this because when
adding the memory@<addr> node regions we can potentially overlap with
multiple reserved regions. This patch fixes this by maintaining a
seperate list of memory reservations and delaying merging them until
after the normal memory init has finished, similar to how DT
reservations are handled.

Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
---
 core/mem_region.c | 37 ++++++++++++++++++++++++++++++-------
 1 file changed, 30 insertions(+), 7 deletions(-)

diff --git a/core/mem_region.c b/core/mem_region.c
index 6d3401d9b9c1..567d260cdbdd 100644
--- a/core/mem_region.c
+++ b/core/mem_region.c
@@ -54,7 +54,9 @@ void mem_dump_allocs(void);
 struct lock mem_region_lock = LOCK_UNLOCKED;
 
 static struct list_head regions = LIST_HEAD_INIT(regions);
+static struct list_head early_reserves = LIST_HEAD_INIT(early_reserves);
 
+static bool mem_region_init_done = false;
 static bool mem_regions_finalised = false;
 
 unsigned long top_of_ram = SKIBOOT_BASE + SKIBOOT_SIZE;
@@ -730,12 +732,17 @@ static bool add_region(struct mem_region *region)
 void mem_reserve_hw(const char *name, uint64_t start, uint64_t len)
 {
 	struct mem_region *region;
-	bool added;
+	bool added = true;
 
 	lock(&mem_region_lock);
 	region = new_region(name, start, len, NULL, REGION_HW_RESERVED);
 	assert(region);
-	added = add_region(region);
+
+	if (!mem_region_init_done)
+		list_add(&early_reserves, &region->list);
+	else
+		added = add_region(region);
+
 	assert(added);
 	unlock(&mem_region_lock);
 }
@@ -821,6 +828,7 @@ bool mem_range_is_reserved(uint64_t start, uint64_t size)
 {
 	uint64_t end = start + size;
 	struct mem_region *region;
+	struct list_head *search;
 
 	/* We may have the range covered by a number of regions, which could
 	 * appear in any order. So, we look for a region that covers the
@@ -832,10 +840,16 @@ bool mem_range_is_reserved(uint64_t start, uint64_t size)
 	 * This has a worst-case of O(n^2), but n is well bounded by the
 	 * small number of reservations.
 	 */
+
+	if (!mem_region_init_done)
+		search = &early_reserves;
+	else
+		search = ®ions;
+
 	for (;;) {
 		bool found = false;
 
-		list_for_each(&regions, region, list) {
+		list_for_each(search, region, list) {
 			if (!region_is_reserved(region))
 				continue;
 
@@ -895,7 +909,7 @@ static void mem_region_parse_reserved_properties(void)
 					dt_get_number(range, 2),
 					dt_get_number(range + 1, 2),
 					NULL, REGION_HW_RESERVED);
-			list_add(&regions, &region->list);
+			add_region(region);
 		}
 	} else if (names || ranges) {
 		prerror("Invalid properties: reserved-names=%p "
@@ -934,7 +948,7 @@ static bool mem_region_parse_reserved_nodes(const char *path)
 				dt_get_number(reg->prop, 2),
 				dt_get_number(reg->prop + sizeof(u64), 2),
 				node, REGION_HW_RESERVED);
-		list_add(&regions, &region->list);
+		add_region(region);
 	}
 
 	return true;
@@ -943,7 +957,7 @@ static bool mem_region_parse_reserved_nodes(const char *path)
 /* Trawl through device tree, create memory regions from nodes. */
 void mem_region_init(void)
 {
-	struct mem_region *region;
+	struct mem_region *region, *next;
 	struct dt_node *i;
 	bool rc;
 
@@ -1003,6 +1017,15 @@ void mem_region_init(void)
 		abort();
 	}
 
+	/* Add reserved reanges from HDAT */
+	list_for_each_safe(&early_reserves, region, next, list) {
+		bool added;
+
+		list_del(&region->list);
+		added = add_region(region);
+		assert(added);
+	}
+
 	/* Add reserved ranges from the DT */
 	rc = mem_region_parse_reserved_nodes("/reserved-memory");
 	if (!rc)
@@ -1011,8 +1034,8 @@ void mem_region_init(void)
 	if (!rc)
 		mem_region_parse_reserved_properties();
 
+	mem_region_init_done = true;
 	unlock(&mem_region_lock);
-
 }
 
 static uint64_t allocated_length(const struct mem_region *r)
-- 
2.9.3