[PATCH] memory hotplug: sysfs and add/remove functions

This adds generic memory add/remove and supporting functions for memory
hotplug into a new file as well as a memory hotplug kernel config option.

Individual architecture patches will follow.

For now, disable memory hotplug when swsusp is enabled.  There's a lot of
churn there right now.  We'll fix it up properly once it calms down.

Signed-off-by: Matt Tolentino <matthew.e.tolentino@intel.com>
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 458 insertions, 0 deletions

diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 66d9c4643fc..f12898d5307 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -7,6 +7,7 @@ obj-y			:= core.o sys.o bus.o dd.o \
 obj-y                   += power/
 obj-$(CONFIG_FW_LOADER) += firmware_class.o
 obj-$(CONFIG_NUMA)      += node.o
+obj-$(CONFIG_MEMORY_HOTPLUG) += memory.o
 
 ifeq ($(CONFIG_DEBUG_DRIVER),y)
 EXTRA_CFLAGS += -DDEBUG
diff --git a/drivers/base/init.c b/drivers/base/init.c
index 84e604e25c4..c648914b9cd 100644
--- a/drivers/base/init.c
+++ b/drivers/base/init.c
@@ -9,6 +9,7 @@
 
 #include <linux/device.h>
 #include <linux/init.h>
+#include <linux/memory.h>
 
 #include "base.h"
 
@@ -33,5 +34,6 @@ void __init driver_init(void)
         platform_bus_init();
         system_bus_init();
         cpu_dev_init();
+        memory_dev_init();
         attribute_container_init();
 }
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
new file mode 100644
index 00000000000..785cb6e6b91
--- /dev/null
+++ b/drivers/base/memory.c
@@ -0,0 +1,455 @@
+/*
+ * drivers/base/memory.c - basic Memory class support
+ *
+ * Written by Matt Tolentino <matthew.e.tolentino@intel.com>
+ *            Dave Hansen <haveblue@us.ibm.com>
+ *
+ * This file provides the necessary infrastructure to represent
+ * a SPARSEMEM-memory-model system's physical memory in /sysfs.
+ * All arch-independent code that assumes MEMORY_HOTPLUG requires
+ * SPARSEMEM should be contained here, or in mm/memory_hotplug.c.
+ */
+
+#include <linux/sysdev.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>        /* capable() */
+#include <linux/topology.h>
+#include <linux/device.h>
+#include <linux/memory.h>
+#include <linux/kobject.h>
+#include <linux/memory_hotplug.h>
+#include <linux/mm.h>
+#include <asm/atomic.h>
+#include <asm/uaccess.h>
+
+#define MEMORY_CLASS_NAME       "memory"
+
+static struct sysdev_class memory_sysdev_class = {
+        set_kset_name(MEMORY_CLASS_NAME),
+};
+EXPORT_SYMBOL(memory_sysdev_class);
+
+static char *memory_hotplug_name(struct kset *kset, struct kobject *kobj)
+{
+        return MEMORY_CLASS_NAME;
+}
+
+static int memory_hotplug(struct kset *kset, struct kobject *kobj, char **envp,
+                        int num_envp, char *buffer, int buffer_size)
+{
+        int retval = 0;
+
+        return retval;
+}
+
+static struct kset_hotplug_ops memory_hotplug_ops = {
+        .name           = memory_hotplug_name,
+        .hotplug        = memory_hotplug,
+};
+
+static struct notifier_block *memory_chain;
+
+static int register_memory_notifier(struct notifier_block *nb)
+{
+        return notifier_chain_register(&memory_chain, nb);
+}
+
+static void unregister_memory_notifier(struct notifier_block *nb)
+{
+        notifier_chain_unregister(&memory_chain, nb);
+}
+
+/*
+ * register_memory - Setup a sysfs device for a memory block
+ */
+static int
+register_memory(struct memory_block *memory, struct mem_section *section,
+                struct node *root)
+{
+        int error;
+
+        memory->sysdev.cls = &memory_sysdev_class;
+        memory->sysdev.id = __section_nr(section);
+
+        error = sysdev_register(&memory->sysdev);
+
+        if (root && !error)
+                error = sysfs_create_link(&root->sysdev.kobj,
+                                          &memory->sysdev.kobj,
+                                          kobject_name(&memory->sysdev.kobj));
+
+        return error;
+}
+
+static void
+unregister_memory(struct memory_block *memory, struct mem_section *section,
+                struct node *root)
+{
+        BUG_ON(memory->sysdev.cls != &memory_sysdev_class);
+        BUG_ON(memory->sysdev.id != __section_nr(section));
+
+        sysdev_unregister(&memory->sysdev);
+        if (root)
+                sysfs_remove_link(&root->sysdev.kobj,
+                                  kobject_name(&memory->sysdev.kobj));
+}
+
+/*
+ * use this as the physical section index that this memsection
+ * uses.
+ */
+
+static ssize_t show_mem_phys_index(struct sys_device *dev, char *buf)
+{
+        struct memory_block *mem =
+                container_of(dev, struct memory_block, sysdev);
+        return sprintf(buf, "%08lx\n", mem->phys_index);
+}
+
+/*
+ * online, offline, going offline, etc.
+ */
+static ssize_t show_mem_state(struct sys_device *dev, char *buf)
+{
+        struct memory_block *mem =
+                container_of(dev, struct memory_block, sysdev);
+        ssize_t len = 0;
+
+        /*
+         * We can probably put these states in a nice little array
+         * so that they're not open-coded
+         */
+        switch (mem->state) {
+                case MEM_ONLINE:
+                        len = sprintf(buf, "online\n");
+                        break;
+                case MEM_OFFLINE:
+                        len = sprintf(buf, "offline\n");
+                        break;
+                case MEM_GOING_OFFLINE:
+                        len = sprintf(buf, "going-offline\n");
+                        break;
+                default:
+                        len = sprintf(buf, "ERROR-UNKNOWN-%ld\n",
+                                        mem->state);
+                        WARN_ON(1);
+                        break;
+        }
+
+        return len;
+}
+
+static inline int memory_notify(unsigned long val, void *v)
+{
+        return notifier_call_chain(&memory_chain, val, v);
+}
+
+/*
+ * MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
+ * OK to have direct references to sparsemem variables in here.
+ */
+static int
+memory_block_action(struct memory_block *mem, unsigned long action)
+{
+        int i;
+        unsigned long psection;
+        unsigned long start_pfn, start_paddr;
+        struct page *first_page;
+        int ret;
+        int old_state = mem->state;
+
+        psection = mem->phys_index;
+        first_page = pfn_to_page(psection << PFN_SECTION_SHIFT);
+
+        /*
+         * The probe routines leave the pages reserved, just
+         * as the bootmem code does.  Make sure they're still
+         * that way.
+         */
+        if (action == MEM_ONLINE) {
+                for (i = 0; i < PAGES_PER_SECTION; i++) {
+                        if (PageReserved(first_page+i))
+                                continue;
+
+                        printk(KERN_WARNING "section number %ld page number %d "
+                                "not reserved, was it already online? \n",
+                                psection, i);
+                        return -EBUSY;
+                }
+        }
+
+        switch (action) {
+                case MEM_ONLINE:
+                        start_pfn = page_to_pfn(first_page);
+                        ret = online_pages(start_pfn, PAGES_PER_SECTION);
+                        break;
+                case MEM_OFFLINE:
+                        mem->state = MEM_GOING_OFFLINE;
+                        memory_notify(MEM_GOING_OFFLINE, NULL);
+                        start_paddr = page_to_pfn(first_page) << PAGE_SHIFT;
+                        ret = remove_memory(start_paddr,
+                                            PAGES_PER_SECTION << PAGE_SHIFT);
+                        if (ret) {
+                                mem->state = old_state;
+                                break;
+                        }
+                        memory_notify(MEM_MAPPING_INVALID, NULL);
+                        break;
+                default:
+                        printk(KERN_WARNING "%s(%p, %ld) unknown action: %ld\n",
+                                        __FUNCTION__, mem, action, action);
+                        WARN_ON(1);
+                        ret = -EINVAL;
+        }
+        /*
+         * For now, only notify on successful memory operations
+         */
+        if (!ret)
+                memory_notify(action, NULL);
+
+        return ret;
+}
+
+static int memory_block_change_state(struct memory_block *mem,
+                unsigned long to_state, unsigned long from_state_req)
+{
+        int ret = 0;
+        down(&mem->state_sem);
+
+        if (mem->state != from_state_req) {
+                ret = -EINVAL;
+                goto out;
+        }
+
+        ret = memory_block_action(mem, to_state);
+        if (!ret)
+                mem->state = to_state;
+
+out:
+        up(&mem->state_sem);
+        return ret;
+}
+
+static ssize_t
+store_mem_state(struct sys_device *dev, const char *buf, size_t count)
+{
+        struct memory_block *mem;
+        unsigned int phys_section_nr;
+        int ret = -EINVAL;
+
+        mem = container_of(dev, struct memory_block, sysdev);
+        phys_section_nr = mem->phys_index;
+
+        if (!valid_section_nr(phys_section_nr))
+                goto out;
+
+        if (!strncmp(buf, "online", min((int)count, 6)))
+                ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
+        else if(!strncmp(buf, "offline", min((int)count, 7)))
+                ret = memory_block_change_state(mem, MEM_OFFLINE, MEM_ONLINE);
+out:
+        if (ret)
+                return ret;
+        return count;
+}
+
+/*
+ * phys_device is a bad name for this.  What I really want
+ * is a way to differentiate between memory ranges that
+ * are part of physical devices that constitute
+ * a complete removable unit or fru.
+ * i.e. do these ranges belong to the same physical device,
+ * s.t. if I offline all of these sections I can then
+ * remove the physical device?
+ */
+static ssize_t show_phys_device(struct sys_device *dev, char *buf)
+{
+        struct memory_block *mem =
+                container_of(dev, struct memory_block, sysdev);
+        return sprintf(buf, "%d\n", mem->phys_device);
+}
+
+static SYSDEV_ATTR(phys_index, 0444, show_mem_phys_index, NULL);
+static SYSDEV_ATTR(state, 0644, show_mem_state, store_mem_state);
+static SYSDEV_ATTR(phys_device, 0444, show_phys_device, NULL);
+
+#define mem_create_simple_file(mem, attr_name)  \
+        sysdev_create_file(&mem->sysdev, &attr_##attr_name)
+#define mem_remove_simple_file(mem, attr_name)  \
+        sysdev_remove_file(&mem->sysdev, &attr_##attr_name)
+
+/*
+ * Block size attribute stuff
+ */
+static ssize_t
+print_block_size(struct class *class, char *buf)
+{
+        return sprintf(buf, "%lx\n", (unsigned long)PAGES_PER_SECTION * PAGE_SIZE);
+}
+
+static CLASS_ATTR(block_size_bytes, 0444, print_block_size, NULL);
+
+static int block_size_init(void)
+{
+        sysfs_create_file(&memory_sysdev_class.kset.kobj,
+                &class_attr_block_size_bytes.attr);
+        return 0;
+}
+
+/*
+ * Some architectures will have custom drivers to do this, and
+ * will not need to do it from userspace.  The fake hot-add code
+ * as well as ppc64 will do all of their discovery in userspace
+ * and will require this interface.
+ */
+#ifdef CONFIG_ARCH_MEMORY_PROBE
+static ssize_t
+memory_probe_store(struct class *class, const char __user *buf, size_t count)
+{
+        u64 phys_addr;
+        int ret;
+
+        phys_addr = simple_strtoull(buf, NULL, 0);
+
+        ret = add_memory(phys_addr, PAGES_PER_SECTION << PAGE_SHIFT);
+
+        if (ret)
+                count = ret;
+
+        return count;
+}
+static CLASS_ATTR(probe, 0700, NULL, memory_probe_store);
+
+static int memory_probe_init(void)
+{
+        sysfs_create_file(&memory_sysdev_class.kset.kobj,
+                &class_attr_probe.attr);
+        return 0;
+}
+#else
+#define memory_probe_init(...)  do {} while (0)
+#endif
+
+/*
+ * Note that phys_device is optional.  It is here to allow for
+ * differentiation between which *physical* devices each
+ * section belongs to...
+ */
+
+static int add_memory_block(unsigned long node_id, struct mem_section *section,
+                     unsigned long state, int phys_device)
+{
+        size_t size = sizeof(struct memory_block);
+        struct memory_block *mem = kmalloc(size, GFP_KERNEL);
+        int ret = 0;
+
+        if (!mem)
+                return -ENOMEM;
+
+        memset(mem, 0, size);
+
+        mem->phys_index = __section_nr(section);
+        mem->state = state;
+        init_MUTEX(&mem->state_sem);
+        mem->phys_device = phys_device;
+
+        ret = register_memory(mem, section, NULL);
+        if (!ret)
+                ret = mem_create_simple_file(mem, phys_index);
+        if (!ret)
+                ret = mem_create_simple_file(mem, state);
+        if (!ret)
+                ret = mem_create_simple_file(mem, phys_device);
+
+        return ret;
+}
+
+/*
+ * For now, we have a linear search to go find the appropriate
+ * memory_block corresponding to a particular phys_index. If
+ * this gets to be a real problem, we can always use a radix
+ * tree or something here.
+ *
+ * This could be made generic for all sysdev classes.
+ */
+static struct memory_block *find_memory_block(struct mem_section *section)
+{
+        struct kobject *kobj;
+        struct sys_device *sysdev;
+        struct memory_block *mem;
+        char name[sizeof(MEMORY_CLASS_NAME) + 9 + 1];
+
+        /*
+         * This only works because we know that section == sysdev->id
+         * slightly redundant with sysdev_register()
+         */
+        sprintf(&name[0], "%s%d", MEMORY_CLASS_NAME, __section_nr(section));
+
+        kobj = kset_find_obj(&memory_sysdev_class.kset, name);
+        if (!kobj)
+                return NULL;
+
+        sysdev = container_of(kobj, struct sys_device, kobj);
+        mem = container_of(sysdev, struct memory_block, sysdev);
+
+        return mem;
+}
+
+int remove_memory_block(unsigned long node_id, struct mem_section *section,
+                int phys_device)
+{
+        struct memory_block *mem;
+
+        mem = find_memory_block(section);
+        mem_remove_simple_file(mem, phys_index);
+        mem_remove_simple_file(mem, state);
+        mem_remove_simple_file(mem, phys_device);
+        unregister_memory(mem, section, NULL);
+
+        return 0;
+}
+
+/*
+ * need an interface for the VM to add new memory regions,
+ * but without onlining it.
+ */
+int register_new_memory(struct mem_section *section)
+{
+        return add_memory_block(0, section, MEM_OFFLINE, 0);
+}
+
+int unregister_memory_section(struct mem_section *section)
+{
+        if (!valid_section(section))
+                return -EINVAL;
+
+        return remove_memory_block(0, section, 0);
+}
+
+/*
+ * Initialize the sysfs support for memory devices...
+ */
+int __init memory_dev_init(void)
+{
+        unsigned int i;
+        int ret;
+
+        memory_sysdev_class.kset.hotplug_ops = &memory_hotplug_ops;
+        ret = sysdev_class_register(&memory_sysdev_class);
+
+        /*
+         * Create entries for memory sections that were found
+         * during boot and have been initialized
+         */
+        for (i = 0; i < NR_MEM_SECTIONS; i++) {
+                if (!valid_section_nr(i))
+                        continue;
+                add_memory_block(0, __nr_to_section(i), MEM_ONLINE, 0);
+        }
+
+        memory_probe_init();
+        block_size_init();
+
+        return ret;
+}