[RFC PATCH v2 41/48] efi_memory: add an event handler to update memory map

[Sughosh Ganu]

There are events that would be used to notify other interested modules
of any changes in available and occupied memory. This would happen
when a module allocates or reserves memory, or frees up memory. These
changes in memory map should be notified to other interested modules
so that the allocated memory does not get overwritten. Add an event
handler in the EFI memory module to update the EFI memory map
accordingly when such changes happen. As a consequence, any subsequent
memory request would honour the updated memory map and only available
memory would be allocated from.

Signed-off-by: Sughosh Ganu <sughosh.ganu at linaro.org>
---
Changes since V1:
* Handle the addition of memory to the LMB memory map.
* Pass the overlap_only_ram parameter to the efi_add_memory_map_pg()
  based on the type of operation.

 lib/efi_loader/Kconfig      |  1 +
 lib/efi_loader/efi_memory.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index bdf5732974..2d90bcef2f 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -16,6 +16,7 @@ config EFI_LOADER
 	select CHARSET
 	# We need to send DM events, dynamically, in the EFI block driver
 	select DM_EVENT
+	select EVENT
 	select EVENT_DYNAMIC
 	select LIB_UUID
 	select LMB
diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
index 5691b5da03..bd12504f72 100644
--- a/lib/efi_loader/efi_memory.c
+++ b/lib/efi_loader/efi_memory.c
@@ -45,6 +45,10 @@ static LIST_HEAD(efi_mem);
 void *efi_bounce_buffer;
 #endif
 
+#define MAP_OP_RESERVE		(u8)0x1
+#define MAP_OP_FREE		(u8)0x2
+#define MAP_OP_ADD		(u8)0x3
+
 /**
  * struct efi_pool_allocation - memory block allocated from pool
  *
@@ -928,3 +932,33 @@ int efi_memory_init(void)
 
 	return 0;
 }
+
+#if CONFIG_IS_ENABLED(MEM_MAP_UPDATE_NOTIFY)
+static int lmb_mem_map_update_sync(void *ctx, struct event *event)
+{
+	u8 op;
+	u64 addr;
+	u64 pages;
+	efi_status_t status;
+	struct event_lmb_map_update *lmb_map = &event->data.lmb_map;
+
+	addr = (uintptr_t)map_sysmem(lmb_map->base, 0);
+	pages = efi_size_in_pages(lmb_map->size + (addr & EFI_PAGE_MASK));
+	op = lmb_map->op;
+	addr &= ~EFI_PAGE_MASK;
+
+	if (op != MAP_OP_RESERVE && op != MAP_OP_FREE && op != MAP_OP_ADD) {
+		log_debug("Invalid map update op received (%d)\n", op);
+		return -1;
+	}
+
+	status = efi_add_memory_map_pg(addr, pages,
+				       op == MAP_OP_RESERVE ?
+				       EFI_BOOT_SERVICES_DATA :
+				       EFI_CONVENTIONAL_MEMORY,
+				       op == MAP_OP_RESERVE ? true : false);
+
+	return status == EFI_SUCCESS ? 0 : -1;
+}
+EVENT_SPY_FULL(EVT_LMB_MAP_UPDATE, lmb_mem_map_update_sync);
+#endif /* MEM_MAP_UPDATE_NOTIFY */
-- 
2.34.1