powerpc/pseries: Add collaborative memory manager

Adds a collaborative memory manager, which acts as a simple balloon driver
for System p machines that support cooperative memory overcommitment
(CMO).

Adds a platform configuration option for CMO called PPC_SMLPAR.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

3 files changed, 492 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig
index 757c0296e0b8..97619fd51e39 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -40,3 +40,26 @@ config PPC_PSERIES_DEBUG
         depends on PPC_PSERIES && PPC_EARLY_DEBUG
         bool "Enable extra debug logging in platforms/pseries"
         default y
+
+config PPC_SMLPAR
+        bool "Support for shared-memory logical partitions"
+        depends on PPC_PSERIES
+        select LPARCFG
+        default n
+        help
+          Select this option to enable shared memory partition support.
+          With this option a system running in an LPAR can be given more
+          memory than physically available and will allow firmware to
+          balance memory across many LPARs.
+
+config CMM
+        tristate "Collaborative memory management"
+        depends on PPC_SMLPAR
+        default y
+        help
+          Select this option, if you want to enable the kernel interface
+          to reduce the memory size of the system. This is accomplished
+          by allocating pages of memory and put them "on hold". This only
+          makes sense for a system running in an LPAR where the unused pages
+          will be reused for other LPARs. The interface allows firmware to
+          balance memory across many LPARs.
diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 554c6e42ef2a..dfe574af2dc0 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -24,3 +24,4 @@ obj-$(CONFIG_HVC_CONSOLE)	+= hvconsole.o
 obj-$(CONFIG_HVCS)              += hvcserver.o
 obj-$(CONFIG_HCALL_STATS)       += hvCall_inst.o
 obj-$(CONFIG_PHYP_DUMP) += phyp_dump.o
+obj-$(CONFIG_CMM)               += cmm.o
diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
new file mode 100644
index 000000000000..c6b3be03168b
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -0,0 +1,468 @@
+/*
+ * Collaborative memory management interface.
+ *
+ * Copyright (C) 2008 IBM Corporation
+ * Author(s): Brian King (brking@linux.vnet.ibm.com),
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/init.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/oom.h>
+#include <linux/sched.h>
+#include <linux/stringify.h>
+#include <linux/swap.h>
+#include <linux/sysdev.h>
+#include <asm/firmware.h>
+#include <asm/hvcall.h>
+#include <asm/mmu.h>
+#include <asm/pgalloc.h>
+#include <asm/uaccess.h>
+
+#include "plpar_wrappers.h"
+
+#define CMM_DRIVER_VERSION      "1.0.0"
+#define CMM_DEFAULT_DELAY       1
+#define CMM_DEBUG                       0
+#define CMM_DISABLE             0
+#define CMM_OOM_KB              1024
+#define CMM_MIN_MEM_MB          256
+#define KB2PAGES(_p)            ((_p)>>(PAGE_SHIFT-10))
+#define PAGES2KB(_p)            ((_p)<<(PAGE_SHIFT-10))
+
+static unsigned int delay = CMM_DEFAULT_DELAY;
+static unsigned int oom_kb = CMM_OOM_KB;
+static unsigned int cmm_debug = CMM_DEBUG;
+static unsigned int cmm_disabled = CMM_DISABLE;
+static unsigned long min_mem_mb = CMM_MIN_MEM_MB;
+static struct sys_device cmm_sysdev;
+
+MODULE_AUTHOR("Brian King <brking@linux.vnet.ibm.com>");
+MODULE_DESCRIPTION("IBM System p Collaborative Memory Manager");
+MODULE_LICENSE("GPL");
+MODULE_VERSION(CMM_DRIVER_VERSION);
+
+module_param_named(delay, delay, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. "
+                 "[Default=" __stringify(CMM_DEFAULT_DELAY) "]");
+module_param_named(oom_kb, oom_kb, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(oom_kb, "Amount of memory in kb to free on OOM. "
+                 "[Default=" __stringify(CMM_OOM_KB) "]");
+module_param_named(min_mem_mb, min_mem_mb, ulong, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(min_mem_mb, "Minimum amount of memory (in MB) to not balloon. "
+                 "[Default=" __stringify(CMM_MIN_MEM_MB) "]");
+module_param_named(debug, cmm_debug, uint, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. "
+                 "[Default=" __stringify(CMM_DEBUG) "]");
+
+#define CMM_NR_PAGES ((PAGE_SIZE - sizeof(void *) - sizeof(unsigned long)) / sizeof(unsigned long))
+
+#define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }
+
+struct cmm_page_array {
+        struct cmm_page_array *next;
+        unsigned long index;
+        unsigned long page[CMM_NR_PAGES];
+};
+
+static unsigned long loaned_pages;
+static unsigned long loaned_pages_target;
+static unsigned long oom_freed_pages;
+
+static struct cmm_page_array *cmm_page_list;
+static DEFINE_SPINLOCK(cmm_lock);
+
+static struct task_struct *cmm_thread_ptr;
+
+/**
+ * cmm_alloc_pages - Allocate pages and mark them as loaned
+ * @nr: number of pages to allocate
+ *
+ * Return value:
+ *      number of pages requested to be allocated which were not
+ **/
+static long cmm_alloc_pages(long nr)
+{
+        struct cmm_page_array *pa, *npa;
+        unsigned long addr;
+        long rc;
+
+        cmm_dbg("Begin request for %ld pages\n", nr);
+
+        while (nr) {
+                addr = __get_free_page(GFP_NOIO | __GFP_NOWARN |
+                                       __GFP_NORETRY | __GFP_NOMEMALLOC);
+                if (!addr)
+                        break;
+                spin_lock(&cmm_lock);
+                pa = cmm_page_list;
+                if (!pa || pa->index >= CMM_NR_PAGES) {
+                        /* Need a new page for the page list. */
+                        spin_unlock(&cmm_lock);
+                        npa = (struct cmm_page_array *)__get_free_page(GFP_NOIO | __GFP_NOWARN |
+                                                                       __GFP_NORETRY | __GFP_NOMEMALLOC);
+                        if (!npa) {
+                                pr_info("%s: Can not allocate new page list\n", __FUNCTION__);
+                                free_page(addr);
+                                break;
+                        }
+                        spin_lock(&cmm_lock);
+                        pa = cmm_page_list;
+
+                        if (!pa || pa->index >= CMM_NR_PAGES) {
+                                npa->next = pa;
+                                npa->index = 0;
+                                pa = npa;
+                                cmm_page_list = pa;
+                        } else
+                                free_page((unsigned long) npa);
+                }
+
+                if ((rc = plpar_page_set_loaned(__pa(addr)))) {
+                        pr_err("%s: Can not set page to loaned. rc=%ld\n", __FUNCTION__, rc);
+                        spin_unlock(&cmm_lock);
+                        free_page(addr);
+                        break;
+                }
+
+                pa->page[pa->index++] = addr;
+                loaned_pages++;
+                totalram_pages--;
+                spin_unlock(&cmm_lock);
+                nr--;
+        }
+
+        cmm_dbg("End request with %ld pages unfulfilled\n", nr);
+        return nr;
+}
+
+/**
+ * cmm_free_pages - Free pages and mark them as active
+ * @nr: number of pages to free
+ *
+ * Return value:
+ *      number of pages requested to be freed which were not
+ **/
+static long cmm_free_pages(long nr)
+{
+        struct cmm_page_array *pa;
+        unsigned long addr;
+
+        cmm_dbg("Begin free of %ld pages.\n", nr);
+        spin_lock(&cmm_lock);
+        pa = cmm_page_list;
+        while (nr) {
+                if (!pa || pa->index <= 0)
+                        break;
+                addr = pa->page[--pa->index];
+
+                if (pa->index == 0) {
+                        pa = pa->next;
+                        free_page((unsigned long) cmm_page_list);
+                        cmm_page_list = pa;
+                }
+
+                plpar_page_set_active(__pa(addr));
+                free_page(addr);
+                loaned_pages--;
+                nr--;
+                totalram_pages++;
+        }
+        spin_unlock(&cmm_lock);
+        cmm_dbg("End request with %ld pages unfulfilled\n", nr);
+        return nr;
+}
+
+/**
+ * cmm_oom_notify - OOM notifier
+ * @self:       notifier block struct
+ * @dummy:      not used
+ * @parm:       returned - number of pages freed
+ *
+ * Return value:
+ *      NOTIFY_OK
+ **/
+static int cmm_oom_notify(struct notifier_block *self,
+                          unsigned long dummy, void *parm)
+{
+        unsigned long *freed = parm;
+        long nr = KB2PAGES(oom_kb);
+
+        cmm_dbg("OOM processing started\n");
+        nr = cmm_free_pages(nr);
+        loaned_pages_target = loaned_pages;
+        *freed += KB2PAGES(oom_kb) - nr;
+        oom_freed_pages += KB2PAGES(oom_kb) - nr;
+        cmm_dbg("OOM processing complete\n");
+        return NOTIFY_OK;
+}
+
+/**
+ * cmm_get_mpp - Read memory performance parameters
+ *
+ * Makes hcall to query the current page loan request from the hypervisor.
+ *
+ * Return value:
+ *      nothing
+ **/
+static void cmm_get_mpp(void)
+{
+        int rc;
+        struct hvcall_mpp_data mpp_data;
+        unsigned long active_pages_target;
+        signed long page_loan_request;
+
+        rc = h_get_mpp(&mpp_data);
+
+        if (rc != H_SUCCESS)
+                return;
+
+        page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE);
+        loaned_pages_target = page_loan_request + loaned_pages;
+        if (loaned_pages_target > oom_freed_pages)
+                loaned_pages_target -= oom_freed_pages;
+        else
+                loaned_pages_target = 0;
+
+        active_pages_target = totalram_pages + loaned_pages - loaned_pages_target;
+
+        if ((min_mem_mb * 1024 * 1024) > (active_pages_target * PAGE_SIZE))
+                loaned_pages_target = totalram_pages + loaned_pages -
+                        ((min_mem_mb * 1024 * 1024) / PAGE_SIZE);
+
+        cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n",
+                page_loan_request, loaned_pages, loaned_pages_target,
+                oom_freed_pages, totalram_pages);
+}
+
+static struct notifier_block cmm_oom_nb = {
+        .notifier_call = cmm_oom_notify
+};
+
+/**
+ * cmm_thread - CMM task thread
+ * @dummy:      not used
+ *
+ * Return value:
+ *      0
+ **/
+static int cmm_thread(void *dummy)
+{
+        unsigned long timeleft;
+
+        while (1) {
+                timeleft = msleep_interruptible(delay * 1000);
+
+                if (kthread_should_stop() || timeleft) {
+                        loaned_pages_target = loaned_pages;
+                        break;
+                }
+
+                cmm_get_mpp();
+
+                if (loaned_pages_target > loaned_pages) {
+                        if (cmm_alloc_pages(loaned_pages_target - loaned_pages))
+                                loaned_pages_target = loaned_pages;
+                } else if (loaned_pages_target < loaned_pages)
+                        cmm_free_pages(loaned_pages - loaned_pages_target);
+        }
+        return 0;
+}
+
+#define CMM_SHOW(name, format, args...)                 \
+        static ssize_t show_##name(struct sys_device *dev, char *buf)   \
+        {                                                       \
+                return sprintf(buf, format, ##args);            \
+        }                                                       \
+        static SYSDEV_ATTR(name, S_IRUGO, show_##name, NULL)
+
+CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages));
+CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
+
+static ssize_t show_oom_pages(struct sys_device *dev, char *buf)
+{
+        return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages));
+}
+
+static ssize_t store_oom_pages(struct sys_device *dev,
+                               const char *buf, size_t count)
+{
+        unsigned long val = simple_strtoul (buf, NULL, 10);
+
+        if (!capable(CAP_SYS_ADMIN))
+                return -EPERM;
+        if (val != 0)
+                return -EBADMSG;
+
+        oom_freed_pages = 0;
+        return count;
+}
+
+static SYSDEV_ATTR(oom_freed_kb, S_IWUSR| S_IRUGO,
+                   show_oom_pages, store_oom_pages);
+
+static struct sysdev_attribute *cmm_attrs[] = {
+        &attr_loaned_kb,
+        &attr_loaned_target_kb,
+        &attr_oom_freed_kb,
+};
+
+static struct sysdev_class cmm_sysdev_class = {
+        .name = "cmm",
+};
+
+/**
+ * cmm_sysfs_register - Register with sysfs
+ *
+ * Return value:
+ *      0 on success / other on failure
+ **/
+static int cmm_sysfs_register(struct sys_device *sysdev)
+{
+        int i, rc;
+
+        if ((rc = sysdev_class_register(&cmm_sysdev_class)))
+                return rc;
+
+        sysdev->id = 0;
+        sysdev->cls = &cmm_sysdev_class;
+
+        if ((rc = sysdev_register(sysdev)))
+                goto class_unregister;
+
+        for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
+                if ((rc = sysdev_create_file(sysdev, cmm_attrs[i])))
+                        goto fail;
+        }
+
+        return 0;
+
+fail:
+        while (--i >= 0)
+                sysdev_remove_file(sysdev, cmm_attrs[i]);
+        sysdev_unregister(sysdev);
+class_unregister:
+        sysdev_class_unregister(&cmm_sysdev_class);
+        return rc;
+}
+
+/**
+ * cmm_unregister_sysfs - Unregister from sysfs
+ *
+ **/
+static void cmm_unregister_sysfs(struct sys_device *sysdev)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
+                sysdev_remove_file(sysdev, cmm_attrs[i]);
+        sysdev_unregister(sysdev);
+        sysdev_class_unregister(&cmm_sysdev_class);
+}
+
+/**
+ * cmm_init - Module initialization
+ *
+ * Return value:
+ *      0 on success / other on failure
+ **/
+static int cmm_init(void)
+{
+        int rc = -ENOMEM;
+
+        if (!firmware_has_feature(FW_FEATURE_CMO))
+                return -EOPNOTSUPP;
+
+        if ((rc = register_oom_notifier(&cmm_oom_nb)) < 0)
+                return rc;
+
+        if ((rc = cmm_sysfs_register(&cmm_sysdev)))
+                goto out_oom_notifier;
+
+        if (cmm_disabled)
+                return rc;
+
+        cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
+        if (IS_ERR(cmm_thread_ptr)) {
+                rc = PTR_ERR(cmm_thread_ptr);
+                goto out_unregister_sysfs;
+        }
+
+        return rc;
+
+out_unregister_sysfs:
+        cmm_unregister_sysfs(&cmm_sysdev);
+out_oom_notifier:
+        unregister_oom_notifier(&cmm_oom_nb);
+        return rc;
+}
+
+/**
+ * cmm_exit - Module exit
+ *
+ * Return value:
+ *      nothing
+ **/
+static void cmm_exit(void)
+{
+        if (cmm_thread_ptr)
+                kthread_stop(cmm_thread_ptr);
+        unregister_oom_notifier(&cmm_oom_nb);
+        cmm_free_pages(loaned_pages);
+        cmm_unregister_sysfs(&cmm_sysdev);
+}
+
+/**
+ * cmm_set_disable - Disable/Enable CMM
+ *
+ * Return value:
+ *      0 on success / other on failure
+ **/
+static int cmm_set_disable(const char *val, struct kernel_param *kp)
+{
+        int disable = simple_strtoul(val, NULL, 10);
+
+        if (disable != 0 && disable != 1)
+                return -EINVAL;
+
+        if (disable && !cmm_disabled) {
+                if (cmm_thread_ptr)
+                        kthread_stop(cmm_thread_ptr);
+                cmm_thread_ptr = NULL;
+                cmm_free_pages(loaned_pages);
+        } else if (!disable && cmm_disabled) {
+                cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
+                if (IS_ERR(cmm_thread_ptr))
+                        return PTR_ERR(cmm_thread_ptr);
+        }
+
+        cmm_disabled = disable;
+        return 0;
+}
+
+module_param_call(disable, cmm_set_disable, param_get_uint,
+                  &cmm_disabled, S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
+                 "[Default=" __stringify(CMM_DISABLE) "]");
+
+module_init(cmm_init);
+module_exit(cmm_exit);