ACPI / memhotplug: Bind removable memory blocks to ACPI device nodes

During ACPI memory hotplug configuration bind memory blocks residing
in modules removable through the standard ACPI mechanism to struct
acpi_device objects associated with ACPI namespace objects
representing those modules.  Accordingly, unbind those memory blocks
from the struct acpi_device objects when the memory modules in
question are being removed.

When "offline" operation for devices representing memory blocks is
introduced, this will allow the ACPI core's device hot-remove code to
use it to carry out remove_memory() for those memory blocks and check
the results of that before it actually removes the modules holding
them from the system.

Since walk_memory_range() is used for accessing all memory blocks
corresponding to a given ACPI namespace object, it is exported from
memory_hotplug.c so that the code in acpi_memhotplug.c can use it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Vasilis Liaskovitis <vasilis.liaskovitis@profitbricks.com>
Reviewed-by: Toshi Kani <toshi.kani@hp.com>

drivers/acpi/acpi_memhotplug.c

@@ -28,6 +28,7 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/memory.h>
 #include <linux/memory_hotplug.h>
 
 #include "internal.h"
@@ -166,13 +167,50 @@ static int acpi_memory_check_device(struct acpi_memory_device *mem_device)
 	return 0;
 }
 
+static unsigned long acpi_meminfo_start_pfn(struct acpi_memory_info *info)
+{
+	return PFN_DOWN(info->start_addr);
+}
+
+static unsigned long acpi_meminfo_end_pfn(struct acpi_memory_info *info)
+{
+	return PFN_UP(info->start_addr + info->length-1);
+}
+
+static int acpi_bind_memblk(struct memory_block *mem, void *arg)
+{
+	return acpi_bind_one(&mem->dev, (acpi_handle)arg);
+}
+
+static int acpi_bind_memory_blocks(struct acpi_memory_info *info,
+				   acpi_handle handle)
+{
+	return walk_memory_range(acpi_meminfo_start_pfn(info),
+				 acpi_meminfo_end_pfn(info), (void *)handle,
+				 acpi_bind_memblk);
+}
+
+static int acpi_unbind_memblk(struct memory_block *mem, void *arg)
+{
+	acpi_unbind_one(&mem->dev);
+	return 0;
+}
+
+static void acpi_unbind_memory_blocks(struct acpi_memory_info *info,
+				      acpi_handle handle)
+{
+	walk_memory_range(acpi_meminfo_start_pfn(info),
+			  acpi_meminfo_end_pfn(info), NULL, acpi_unbind_memblk);
+}
+
 static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 {
+	acpi_handle handle = mem_device->device->handle;
 	int result, num_enabled = 0;
 	struct acpi_memory_info *info;
 	int node;
 
-	node = acpi_get_node(mem_device->device->handle);
+	node = acpi_get_node(handle);
 	/*
 	 * Tell the VM there is more memory here...
 	 * Note: Assume that this function returns zero on success
@@ -203,6 +241,12 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 		if (result && result != -EEXIST)
 			continue;
 
+		result = acpi_bind_memory_blocks(info, handle);
+		if (result) {
+			acpi_unbind_memory_blocks(info, handle);
+			return -ENODEV;
+		}
+
 		info->enabled = 1;
 
 		/*
@@ -229,17 +273,20 @@ static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 
 static int acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
 {
+	acpi_handle handle = mem_device->device->handle;
 	int result = 0, nid;
 	struct acpi_memory_info *info, *n;
 
-	nid = acpi_get_node(mem_device->device->handle);
+	nid = acpi_get_node(handle);
 
 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
 		if (!info->enabled)
 			continue;
 
 		if (nid < 0)
 			nid = memory_add_physaddr_to_nid(info->start_addr);
+
+		acpi_unbind_memory_blocks(info, handle);
 		result = remove_memory(nid, info->start_addr, info->length);
 		if (result)
 			return result;
@@ -300,7 +347,7 @@ static int acpi_memory_device_add(struct acpi_device *device,
 	if (result) {
 		dev_err(&device->dev, "acpi_memory_enable_device() error\n");
 		acpi_memory_device_free(mem_device);
-		return -ENODEV;
+		return result;
 	}
 
 	dev_dbg(&device->dev, "Memory device configured by ACPI\n");

include/linux/memory_hotplug.h

@@ -245,6 +245,8 @@ static inline int is_mem_section_removable(unsigned long pfn,
 static inline void try_offline_node(int nid) {}
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
+extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+		void *arg, int (*func)(struct memory_block *, void *));
 extern int mem_online_node(int nid);
 extern int add_memory(int nid, u64 start, u64 size);
 extern int arch_add_memory(int nid, u64 start, u64 size);

mm/memory_hotplug.c

@@ -1618,6 +1618,7 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
 {
 	return __offline_pages(start_pfn, start_pfn + nr_pages, 120 * HZ);
 }
+#endif /* CONFIG_MEMORY_HOTREMOVE */
 
 /**
  * walk_memory_range - walks through all mem sections in [start_pfn, end_pfn)
@@ -1631,7 +1632,7 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
  *
  * Returns the return value of func.
  */
-static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
+int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
 		void *arg, int (*func)(struct memory_block *, void *))
 {
 	struct memory_block *mem = NULL;
@@ -1668,6 +1669,7 @@ static int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
 	return 0;
 }
 
+#ifdef CONFIG_MEMORY_HOTREMOVE
 /**
  * offline_memory_block_cb - callback function for offlining memory block
  * @mem: the memory block to be offlined