1 files changed, 719 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c
new file mode 100644
index 000000000..45a3a3022
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/cmm.c
@@ -0,0 +1,719 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Collaborative memory management interface.
+ *
+ * Copyright (C) 2008 IBM Corporation
+ * Author(s): Brian King (brking@linux.vnet.ibm.com),
+ */
+
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/oom.h>
+#include <linux/reboot.h>
+#include <linux/sched.h>
+#include <linux/stringify.h>
+#include <linux/swap.h>
+#include <linux/device.h>
+#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
+#include <linux/magic.h>
+#include <linux/balloon_compaction.h>
+#include <asm/firmware.h>
+#include <asm/hvcall.h>
+#include <asm/mmu.h>
+#include <linux/uaccess.h>
+#include <linux/memory.h>
+#include <asm/plpar_wrappers.h>
+
+#include "pseries.h"
+
+#define CMM_DRIVER_VERSION	"1.0.0"
+#define CMM_DEFAULT_DELAY	1
+#define CMM_HOTPLUG_DELAY	5
+#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))
+
+#define CMM_MEM_HOTPLUG_PRI	1
+
+static unsigned int delay = CMM_DEFAULT_DELAY;
+static unsigned int hotplug_delay = CMM_HOTPLUG_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 bool __read_mostly simulate;
+static unsigned long simulate_loan_target_kb;
+static struct device cmm_dev;
+
+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, 0644);
+MODULE_PARM_DESC(delay, "Delay (in seconds) between polls to query hypervisor paging requests. "
+		 "[Default=" __stringify(CMM_DEFAULT_DELAY) "]");
+module_param_named(hotplug_delay, hotplug_delay, uint, 0644);
+MODULE_PARM_DESC(hotplug_delay, "Delay (in seconds) after memory hotplug remove "
+		 "before loaning resumes. "
+		 "[Default=" __stringify(CMM_HOTPLUG_DELAY) "]");
+module_param_named(oom_kb, oom_kb, uint, 0644);
+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, 0644);
+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, 0644);
+MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. "
+		 "[Default=" __stringify(CMM_DEBUG) "]");
+module_param_named(simulate, simulate, bool, 0444);
+MODULE_PARM_DESC(simulate, "Enable simulation mode (no communication with hw).");
+
+#define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); }
+
+static atomic_long_t loaned_pages;
+static unsigned long loaned_pages_target;
+static unsigned long oom_freed_pages;
+
+static DEFINE_MUTEX(hotplug_mutex);
+static int hotplug_occurred; /* protected by the hotplug mutex */
+
+static struct task_struct *cmm_thread_ptr;
+static struct balloon_dev_info b_dev_info;
+
+static long plpar_page_set_loaned(struct page *page)
+{
+	const unsigned long vpa = page_to_phys(page);
+	unsigned long cmo_page_sz = cmo_get_page_size();
+	long rc = 0;
+	int i;
+
+	if (unlikely(simulate))
+		return 0;
+
+	for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
+		rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED, vpa + i, 0);
+
+	for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz)
+		plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE,
+				   vpa + i - cmo_page_sz, 0);
+
+	return rc;
+}
+
+static long plpar_page_set_active(struct page *page)
+{
+	const unsigned long vpa = page_to_phys(page);
+	unsigned long cmo_page_sz = cmo_get_page_size();
+	long rc = 0;
+	int i;
+
+	if (unlikely(simulate))
+		return 0;
+
+	for (i = 0; !rc && i < PAGE_SIZE; i += cmo_page_sz)
+		rc = plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_ACTIVE, vpa + i, 0);
+
+	for (i -= cmo_page_sz; rc && i != 0; i -= cmo_page_sz)
+		plpar_hcall_norets(H_PAGE_INIT, H_PAGE_SET_LOANED,
+				   vpa + i - cmo_page_sz, 0);
+
+	return rc;
+}
+
+/**
+ * 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 page *page;
+	long rc;
+
+	cmm_dbg("Begin request for %ld pages\n", nr);
+
+	while (nr) {
+		/* Exit if a hotplug operation is in progress or occurred */
+		if (mutex_trylock(&hotplug_mutex)) {
+			if (hotplug_occurred) {
+				mutex_unlock(&hotplug_mutex);
+				break;
+			}
+			mutex_unlock(&hotplug_mutex);
+		} else {
+			break;
+		}
+
+		page = balloon_page_alloc();
+		if (!page)
+			break;
+		rc = plpar_page_set_loaned(page);
+		if (rc) {
+			pr_err("%s: Can not set page to loaned. rc=%ld\n", __func__, rc);
+			__free_page(page);
+			break;
+		}
+
+		balloon_page_enqueue(&b_dev_info, page);
+		atomic_long_inc(&loaned_pages);
+		adjust_managed_page_count(page, -1);
+		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 page *page;
+
+	cmm_dbg("Begin free of %ld pages.\n", nr);
+	while (nr) {
+		page = balloon_page_dequeue(&b_dev_info);
+		if (!page)
+			break;
+		plpar_page_set_active(page);
+		adjust_managed_page_count(page, 1);
+		__free_page(page);
+		atomic_long_dec(&loaned_pages);
+		nr--;
+	}
+	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 = atomic_long_read(&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)
+{
+	const long __loaned_pages = atomic_long_read(&loaned_pages);
+	const long total_pages = totalram_pages() + __loaned_pages;
+	int rc;
+	struct hvcall_mpp_data mpp_data;
+	signed long active_pages_target, page_loan_request, target;
+	signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE;
+
+	if (likely(!simulate)) {
+		rc = h_get_mpp(&mpp_data);
+		if (rc != H_SUCCESS)
+			return;
+		page_loan_request = div_s64((s64)mpp_data.loan_request,
+					    PAGE_SIZE);
+		target = page_loan_request + __loaned_pages;
+	} else {
+		target = KB2PAGES(simulate_loan_target_kb);
+		page_loan_request = target - __loaned_pages;
+	}
+
+	if (target < 0 || total_pages < min_mem_pages)
+		target = 0;
+
+	if (target > oom_freed_pages)
+		target -= oom_freed_pages;
+	else
+		target = 0;
+
+	active_pages_target = total_pages - target;
+
+	if (min_mem_pages > active_pages_target)
+		target = total_pages - min_mem_pages;
+
+	if (target < 0)
+		target = 0;
+
+	loaned_pages_target = target;
+
+	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;
+	long __loaned_pages;
+
+	while (1) {
+		timeleft = msleep_interruptible(delay * 1000);
+
+		if (kthread_should_stop() || timeleft)
+			break;
+
+		if (mutex_trylock(&hotplug_mutex)) {
+			if (hotplug_occurred) {
+				hotplug_occurred = 0;
+				mutex_unlock(&hotplug_mutex);
+				cmm_dbg("Hotplug operation has occurred, "
+						"loaning activity suspended "
+						"for %d seconds.\n",
+						hotplug_delay);
+				timeleft = msleep_interruptible(hotplug_delay *
+						1000);
+				if (kthread_should_stop() || timeleft)
+					break;
+				continue;
+			}
+			mutex_unlock(&hotplug_mutex);
+		} else {
+			cmm_dbg("Hotplug operation in progress, activity "
+					"suspended\n");
+			continue;
+		}
+
+		cmm_get_mpp();
+
+		__loaned_pages = atomic_long_read(&loaned_pages);
+		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 device *dev,	\
+				   struct device_attribute *attr,	\
+				   char *buf)			\
+	{							\
+		return sprintf(buf, format, ##args);		\
+	}							\
+	static DEVICE_ATTR(name, 0444, show_##name, NULL)
+
+CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(atomic_long_read(&loaned_pages)));
+CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target));
+
+static ssize_t show_oom_pages(struct device *dev,
+			      struct device_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%lu\n", PAGES2KB(oom_freed_pages));
+}
+
+static ssize_t store_oom_pages(struct device *dev,
+			       struct device_attribute *attr,
+			       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 DEVICE_ATTR(oom_freed_kb, 0644,
+		   show_oom_pages, store_oom_pages);
+
+static struct device_attribute *cmm_attrs[] = {
+	&dev_attr_loaned_kb,
+	&dev_attr_loaned_target_kb,
+	&dev_attr_oom_freed_kb,
+};
+
+static DEVICE_ULONG_ATTR(simulate_loan_target_kb, 0644,
+			 simulate_loan_target_kb);
+
+static struct bus_type cmm_subsys = {
+	.name = "cmm",
+	.dev_name = "cmm",
+};
+
+static void cmm_release_device(struct device *dev)
+{
+}
+
+/**
+ * cmm_sysfs_register - Register with sysfs
+ *
+ * Return value:
+ * 	0 on success / other on failure
+ **/
+static int cmm_sysfs_register(struct device *dev)
+{
+	int i, rc;
+
+	if ((rc = subsys_system_register(&cmm_subsys, NULL)))
+		return rc;
+
+	dev->id = 0;
+	dev->bus = &cmm_subsys;
+	dev->release = cmm_release_device;
+
+	if ((rc = device_register(dev)))
+		goto subsys_unregister;
+
+	for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++) {
+		if ((rc = device_create_file(dev, cmm_attrs[i])))
+			goto fail;
+	}
+
+	if (!simulate)
+		return 0;
+	rc = device_create_file(dev, &dev_attr_simulate_loan_target_kb.attr);
+	if (rc)
+		goto fail;
+	return 0;
+
+fail:
+	while (--i >= 0)
+		device_remove_file(dev, cmm_attrs[i]);
+	device_unregister(dev);
+subsys_unregister:
+	bus_unregister(&cmm_subsys);
+	return rc;
+}
+
+/**
+ * cmm_unregister_sysfs - Unregister from sysfs
+ *
+ **/
+static void cmm_unregister_sysfs(struct device *dev)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(cmm_attrs); i++)
+		device_remove_file(dev, cmm_attrs[i]);
+	device_unregister(dev);
+	bus_unregister(&cmm_subsys);
+}
+
+/**
+ * cmm_reboot_notifier - Make sure pages are not still marked as "loaned"
+ *
+ **/
+static int cmm_reboot_notifier(struct notifier_block *nb,
+			       unsigned long action, void *unused)
+{
+	if (action == SYS_RESTART) {
+		if (cmm_thread_ptr)
+			kthread_stop(cmm_thread_ptr);
+		cmm_thread_ptr = NULL;
+		cmm_free_pages(atomic_long_read(&loaned_pages));
+	}
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block cmm_reboot_nb = {
+	.notifier_call = cmm_reboot_notifier,
+};
+
+/**
+ * cmm_memory_cb - Handle memory hotplug notifier calls
+ * @self:	notifier block struct
+ * @action:	action to take
+ * @arg:	struct memory_notify data for handler
+ *
+ * Return value:
+ *	NOTIFY_OK or notifier error based on subfunction return value
+ *
+ **/
+static int cmm_memory_cb(struct notifier_block *self,
+			unsigned long action, void *arg)
+{
+	int ret = 0;
+
+	switch (action) {
+	case MEM_GOING_OFFLINE:
+		mutex_lock(&hotplug_mutex);
+		hotplug_occurred = 1;
+		break;
+	case MEM_OFFLINE:
+	case MEM_CANCEL_OFFLINE:
+		mutex_unlock(&hotplug_mutex);
+		cmm_dbg("Memory offline operation complete.\n");
+		break;
+	case MEM_GOING_ONLINE:
+	case MEM_ONLINE:
+	case MEM_CANCEL_ONLINE:
+		break;
+	}
+
+	return notifier_from_errno(ret);
+}
+
+static struct notifier_block cmm_mem_nb = {
+	.notifier_call = cmm_memory_cb,
+	.priority = CMM_MEM_HOTPLUG_PRI
+};
+
+#ifdef CONFIG_BALLOON_COMPACTION
+static struct vfsmount *balloon_mnt;
+
+static int cmm_init_fs_context(struct fs_context *fc)
+{
+	return init_pseudo(fc, PPC_CMM_MAGIC) ? 0 : -ENOMEM;
+}
+
+static struct file_system_type balloon_fs = {
+	.name = "ppc-cmm",
+	.init_fs_context = cmm_init_fs_context,
+	.kill_sb = kill_anon_super,
+};
+
+static int cmm_migratepage(struct balloon_dev_info *b_dev_info,
+			   struct page *newpage, struct page *page,
+			   enum migrate_mode mode)
+{
+	unsigned long flags;
+
+	/*
+	 * loan/"inflate" the newpage first.
+	 *
+	 * We might race against the cmm_thread who might discover after our
+	 * loan request that another page is to be unloaned. However, once
+	 * the cmm_thread runs again later, this error will automatically
+	 * be corrected.
+	 */
+	if (plpar_page_set_loaned(newpage)) {
+		/* Unlikely, but possible. Tell the caller not to retry now. */
+		pr_err_ratelimited("%s: Cannot set page to loaned.", __func__);
+		return -EBUSY;
+	}
+
+	/* balloon page list reference */
+	get_page(newpage);
+
+	/*
+	 * When we migrate a page to a different zone, we have to fixup the
+	 * count of both involved zones as we adjusted the managed page count
+	 * when inflating.
+	 */
+	if (page_zone(page) != page_zone(newpage)) {
+		adjust_managed_page_count(page, 1);
+		adjust_managed_page_count(newpage, -1);
+	}
+
+	spin_lock_irqsave(&b_dev_info->pages_lock, flags);
+	balloon_page_insert(b_dev_info, newpage);
+	balloon_page_delete(page);
+	b_dev_info->isolated_pages--;
+	spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
+
+	/*
+	 * activate/"deflate" the old page. We ignore any errors just like the
+	 * other callers.
+	 */
+	plpar_page_set_active(page);
+
+	/* balloon page list reference */
+	put_page(page);
+
+	return MIGRATEPAGE_SUCCESS;
+}
+
+static int cmm_balloon_compaction_init(void)
+{
+	int rc;
+
+	balloon_devinfo_init(&b_dev_info);
+	b_dev_info.migratepage = cmm_migratepage;
+
+	balloon_mnt = kern_mount(&balloon_fs);
+	if (IS_ERR(balloon_mnt)) {
+		rc = PTR_ERR(balloon_mnt);
+		balloon_mnt = NULL;
+		return rc;
+	}
+
+	b_dev_info.inode = alloc_anon_inode(balloon_mnt->mnt_sb);
+	if (IS_ERR(b_dev_info.inode)) {
+		rc = PTR_ERR(b_dev_info.inode);
+		b_dev_info.inode = NULL;
+		kern_unmount(balloon_mnt);
+		balloon_mnt = NULL;
+		return rc;
+	}
+
+	b_dev_info.inode->i_mapping->a_ops = &balloon_aops;
+	return 0;
+}
+static void cmm_balloon_compaction_deinit(void)
+{
+	if (b_dev_info.inode)
+		iput(b_dev_info.inode);
+	b_dev_info.inode = NULL;
+	kern_unmount(balloon_mnt);
+	balloon_mnt = NULL;
+}
+#else /* CONFIG_BALLOON_COMPACTION */
+static int cmm_balloon_compaction_init(void)
+{
+	return 0;
+}
+
+static void cmm_balloon_compaction_deinit(void)
+{
+}
+#endif /* CONFIG_BALLOON_COMPACTION */
+
+/**
+ * cmm_init - Module initialization
+ *
+ * Return value:
+ * 	0 on success / other on failure
+ **/
+static int cmm_init(void)
+{
+	int rc;
+
+	if (!firmware_has_feature(FW_FEATURE_CMO) && !simulate)
+		return -EOPNOTSUPP;
+
+	rc = cmm_balloon_compaction_init();
+	if (rc)
+		return rc;
+
+	rc = register_oom_notifier(&cmm_oom_nb);
+	if (rc < 0)
+		goto out_balloon_compaction;
+
+	if ((rc = register_reboot_notifier(&cmm_reboot_nb)))
+		goto out_oom_notifier;
+
+	if ((rc = cmm_sysfs_register(&cmm_dev)))
+		goto out_reboot_notifier;
+
+	rc = register_memory_notifier(&cmm_mem_nb);
+	if (rc)
+		goto out_unregister_notifier;
+
+	if (cmm_disabled)
+		return 0;
+
+	cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread");
+	if (IS_ERR(cmm_thread_ptr)) {
+		rc = PTR_ERR(cmm_thread_ptr);
+		goto out_unregister_notifier;
+	}
+
+	return 0;
+out_unregister_notifier:
+	unregister_memory_notifier(&cmm_mem_nb);
+	cmm_unregister_sysfs(&cmm_dev);
+out_reboot_notifier:
+	unregister_reboot_notifier(&cmm_reboot_nb);
+out_oom_notifier:
+	unregister_oom_notifier(&cmm_oom_nb);
+out_balloon_compaction:
+	cmm_balloon_compaction_deinit();
+	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);
+	unregister_reboot_notifier(&cmm_reboot_nb);
+	unregister_memory_notifier(&cmm_mem_nb);
+	cmm_free_pages(atomic_long_read(&loaned_pages));
+	cmm_unregister_sysfs(&cmm_dev);
+	cmm_balloon_compaction_deinit();
+}
+
+/**
+ * cmm_set_disable - Disable/Enable CMM
+ *
+ * Return value:
+ * 	0 on success / other on failure
+ **/
+static int cmm_set_disable(const char *val, const 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(atomic_long_read(&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, 0644);
+MODULE_PARM_DESC(disable, "Disable CMM. Set to 1 to disable. "
+		 "[Default=" __stringify(CMM_DISABLE) "]");
+
+module_init(cmm_init);
+module_exit(cmm_exit);