From: Jérôme Glisse <jglisse@xxxxxxxxxx>
This patch only introduce core HMM functions for registering a new mirror and
stopping a mirror as well as registering and unregistering a device.
The lifecycle of HMM object is handled differently then one of mmu_notifier
because unlike mmu_notifier there can be concurrent call from both mm code to
HMM code and/or from device driver code to HMM code. Moreover lifetime of HMM
can be uncorrelated from the lifetime of the process that is being mirror.
Changed since v1:
- Updated comment of hmm_device_register().
Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx>
Signed-off-by: Sherry Cheung <SCheung@xxxxxxxxxx>
Signed-off-by: Subhash Gutti <sgutti@xxxxxxxxxx>
Signed-off-by: Mark Hairgrove <mhairgrove@xxxxxxxxxx>
Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
Signed-off-by: Jatin Kumar <jakumar@xxxxxxxxxx>
---
MAINTAINERS | 7 +
include/linux/hmm.h | 129 ++++++++++++++++
include/linux/mm.h | 11 ++
include/linux/mm_types.h | 14 ++
kernel/fork.c | 2 +
mm/Kconfig | 15 ++
mm/Makefile | 1 +
mm/hmm.c | 373 +++++++++++++++++++++++++++++++++++++++++++++++
8 files changed, 552 insertions(+)
create mode 100644 include/linux/hmm.h
create mode 100644 mm/hmm.c
diff --git a/MAINTAINERS b/MAINTAINERS
index c03bc6c..3ec87c4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4533,6 +4533,13 @@ F: include/uapi/linux/if_hippi.h
F: net/802/hippi.c
F: drivers/net/hippi/
+HMM - Heterogeneous Memory Management
+M: Jérôme Glisse <jglisse@xxxxxxxxxx>
+L: linux-mm@xxxxxxxxx
+S: Maintained
+F: mm/hmm.c
+F: include/linux/hmm.h
+
HOST AP DRIVER
M: Jouni Malinen <j@xxxxx>
L: hostap@xxxxxxxxx (subscribers-only)
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
new file mode 100644
index 0000000..8eddc15
--- /dev/null
+++ b/include/linux/hmm.h
@@ -0,0 +1,129 @@
+/*
+ * Copyright 2013 Red Hat Inc.
+ *
+ * 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.
+ *
+ * Authors: Jérôme Glisse <jglisse@xxxxxxxxxx>
+ */
+/* This is a heterogeneous memory management (hmm). In a nutshell this provide
+ * an API to mirror a process address on a device which has its own mmu using
+ * its own page table for the process. It supports everything except special
+ * vma.
+ *
+ * Mandatory hardware features :
+ * - An mmu with pagetable.
+ * - Read only flag per cpu page.
+ * - Page fault ie hardware must stop and wait for kernel to service fault.
+ *
+ * Optional hardware features :
+ * - Dirty bit per cpu page.
+ * - Access bit per cpu page.
+ *
+ * The hmm code handle all the interfacing with the core kernel mm code and
+ * provide a simple API. It does support migrating system memory to device
+ * memory and handle migration back to system memory on cpu page fault.
+ *
+ * Migrated memory is considered as swaped from cpu and core mm code point of
+ * view.
+ */
+#ifndef _HMM_H
+#define _HMM_H
+
+#ifdef CONFIG_HMM
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/atomic.h>
+#include <linux/mm_types.h>
+#include <linux/mmu_notifier.h>
+#include <linux/workqueue.h>
+#include <linux/mman.h>
+
+
+struct hmm_device;
+struct hmm_mirror;
+struct hmm;
+
+
+/* hmm_device - Each device must register one and only one hmm_device.
+ *
+ * The hmm_device is the link btw HMM and each device driver.
+ */
+
+/* struct hmm_device_operations - HMM device operation callback
+ */
+struct hmm_device_ops {
+ /* release() - mirror must stop using the address space.
+ *
+ * @mirror: The mirror that link process address space with the device.
+ *
+ * This callback is call either on mm destruction or as result to a
+ * call to hmm_mirror_release(). Device driver have to stop all hw
+ * thread and all usage of the address space, it has to dirty all pages
+ * that have been dirty by the device. But it must not clear any entry
+ * from the mirror page table.
+ */
+ void (*release)(struct hmm_mirror *mirror);
+};
+
+/* struct hmm_device - per device HMM structure
+ *
+ * @name: Device name (uniquely identify the device on the system).
+ * @ops: The hmm operations callback.
+ * @mirrors: List of all active mirrors for the device.
+ * @mutex: Mutex protecting mirrors list.
+ *
+ * Each device that want to mirror an address space must register one of this
+ * struct (only once per linux device).
+ */
+struct hmm_device {
+ const char *name;
+ const struct hmm_device_ops *ops;
+ struct list_head mirrors;
+ struct mutex mutex;
+};
+
+int hmm_device_register(struct hmm_device *device);
+int hmm_device_unregister(struct hmm_device *device);
+
+
+/* hmm_mirror - device specific mirroring functions.
+ *
+ * Each device that mirror a process has a uniq hmm_mirror struct associating
+ * the process address space with the device. Same process can be mirrored by
+ * several different devices at the same time.
+ */
+
+/* struct hmm_mirror - per device and per mm HMM structure
+ *
+ * @device: The hmm_device struct this hmm_mirror is associated to.
+ * @hmm: The hmm struct this hmm_mirror is associated to.
+ * @dlist: List of all hmm_mirror for same device.
+ * @mlist: List of all hmm_mirror for same process.
+ *
+ * Each device that want to mirror an address space must register one of this
+ * struct for each of the address space it wants to mirror. Same device can
+ * mirror several different address space. As well same address space can be
+ * mirror by different devices.
+ */
+struct hmm_mirror {
+ struct hmm_device *device;
+ struct hmm *hmm;
+ struct list_head dlist;
+ struct hlist_node mlist;
+};
+
+int hmm_mirror_register(struct hmm_mirror *mirror, struct hmm_device *device);
+void hmm_mirror_unregister(struct hmm_mirror *mirror);
+
+
+#endif /* CONFIG_HMM */
+#endif
diff --git a/include/linux/mm.h b/include/linux/mm.h
index f80d019..0e054f9 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2208,5 +2208,16 @@ void __init setup_nr_node_ids(void);
static inline void setup_nr_node_ids(void) {}
#endif
+#ifdef CONFIG_HMM
+static inline void hmm_mm_init(struct mm_struct *mm)
+{
+ mm->hmm = NULL;
+}
+#else /* !CONFIG_HMM */
+static inline void hmm_mm_init(struct mm_struct *mm)
+{
+}
+#endif /* !CONFIG_HMM */
+
#endif /* __KERNEL__ */
#endif /* _LINUX_MM_H */
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 6d34aa2..57a3e1c 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -15,6 +15,10 @@
#include <asm/page.h>
#include <asm/mmu.h>
+#ifdef CONFIG_HMM
+struct hmm;
+#endif
+
#ifndef AT_VECTOR_SIZE_ARCH
#define AT_VECTOR_SIZE_ARCH 0
#endif
@@ -426,6 +430,16 @@ struct mm_struct {
#ifdef CONFIG_MMU_NOTIFIER
struct mmu_notifier_mm *mmu_notifier_mm;
#endif
+#ifdef CONFIG_HMM
+ /*
+ * hmm always register an mmu_notifier we rely on mmu notifier to keep
+ * refcount on mm struct as well as forbiding registering hmm on a
+ * dying mm
+ *
+ * This field is set with mmap_sem old in write mode.
+ */
+ struct hmm *hmm;
+#endif
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
pgtable_t pmd_huge_pte; /* protected by page_table_lock */
#endif
diff --git a/kernel/fork.c b/kernel/fork.c
index 4dc2dda..0bb9dc4 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -27,6 +27,7 @@
#include <linux/binfmts.h>
#include <linux/mman.h>
#include <linux/mmu_notifier.h>
+#include <linux/hmm.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/vmacache.h>
@@ -568,6 +569,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p)
mm_init_aio(mm);
mm_init_owner(mm, p);
mmu_notifier_mm_init(mm);
+ hmm_mm_init(mm);
clear_tlb_flush_pending(mm);
#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && !USE_SPLIT_PMD_PTLOCKS
mm->pmd_huge_pte = NULL;
diff --git a/mm/Kconfig b/mm/Kconfig
index 1d1ae6b..b249db0 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -618,3 +618,18 @@ config MAX_STACK_SIZE_MB
changed to a smaller value in which case that is used.
A sane initial value is 80 MB.
+
+if STAGING
+config HMM
+ bool "Enable heterogeneous memory management (HMM)"
+ depends on MMU
+ select MMU_NOTIFIER
+ select GENERIC_PAGE_TABLE
+ default n
+ help
+ Heterogeneous memory management provide infrastructure for a device
+ to mirror a process address space into an hardware mmu or into any
+ things supporting pagefault like event.
+
+ If unsure, say N to disable hmm.
+endif # STAGING
diff --git a/mm/Makefile b/mm/Makefile
index 3548460..cb2f9ed 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -73,3 +73,4 @@ obj-$(CONFIG_GENERIC_EARLY_IOREMAP) += early_ioremap.o
obj-$(CONFIG_CMA) += cma.o
obj-$(CONFIG_MEMORY_BALLOON) += balloon_compaction.o
obj-$(CONFIG_PAGE_EXTENSION) += page_ext.o
+obj-$(CONFIG_HMM) += hmm.o
diff --git a/mm/hmm.c b/mm/hmm.c
new file mode 100644
index 0000000..0b4e220
--- /dev/null
+++ b/mm/hmm.c
@@ -0,0 +1,373 @@
+/*
+ * Copyright 2013 Red Hat Inc.
+ *
+ * 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.
+ *
+ * Authors: Jérôme Glisse <jglisse@xxxxxxxxxx>
+ */
+/* This is the core code for heterogeneous memory management (HMM). HMM intend
+ * to provide helper for mirroring a process address space on a device as well
+ * as allowing migration of data between system memory and device memory refer
+ * as remote memory from here on out.
+ *
+ * Refer to include/linux/hmm.h for further information on general design.
+ */
+#include <linux/export.h>
+#include <linux/bitmap.h>
+#include <linux/list.h>
+#include <linux/rculist.h>
+#include <linux/slab.h>
+#include <linux/mmu_notifier.h>
+#include <linux/mm.h>
+#include <linux/hugetlb.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/ksm.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+#include <linux/swapops.h>
+#include <linux/mmu_context.h>
+#include <linux/memcontrol.h>
+#include <linux/hmm.h>
+#include <linux/wait.h>
+#include <linux/mman.h>
+#include <linux/delay.h>
+#include <linux/workqueue.h>
+
+#include "internal.h"
+
+static struct srcu_struct srcu;
+
+
+/* struct hmm - per mm_struct HMM states.
+ *
+ * @mirrors: List of all mirror for this mm (one per device).
+ * @mm: The mm struct this hmm is associated with.
+ * @vm_end: Last valid address for this mm (exclusive).
+ * @lock: Serialize the mirror list modifications.
+ * @kref: Reference counter
+ * @mmu_notifier: The mmu_notifier of this mm.
+ *
+ * For each process address space (mm_struct) there is one and only one hmm
+ * struct. hmm functions will redispatch to each devices the change made to
+ * the process address space.
+ */
+struct hmm {
+ struct hlist_head mirrors;
+ struct mm_struct *mm;
+ unsigned long vm_end;
+ spinlock_t lock;
+ struct kref kref;
+ struct mmu_notifier mmu_notifier;
+};
+
+static struct mmu_notifier_ops hmm_notifier_ops;
+
+
+/* hmm - core HMM functions.
+ *
+ * Core HMM functions that deal with all the process mm activities.
+ */
+
+static int hmm_init(struct hmm *hmm)
+{
+ hmm->mm = current->mm;
+ hmm->vm_end = TASK_SIZE;
+ kref_init(&hmm->kref);
+ INIT_HLIST_HEAD(&hmm->mirrors);
+ spin_lock_init(&hmm->lock);
+
+ /* register notifier */
+ hmm->mmu_notifier.ops = &hmm_notifier_ops;
+ return __mmu_notifier_register(&hmm->mmu_notifier, current->mm);
+}
+
+static int hmm_add_mirror(struct hmm *hmm, struct hmm_mirror *mirror)
+{
+ struct hmm_mirror *tmp;
+
+ spin_lock(&hmm->lock);
+ hlist_for_each_entry_rcu(tmp, &hmm->mirrors, mlist)
+ if (tmp->device == mirror->device) {
+ /* Same device can mirror only once. */
+ spin_unlock(&hmm->lock);
+ return -EINVAL;
+ }
+ hlist_add_head(&mirror->mlist, &hmm->mirrors);
+ spin_unlock(&hmm->lock);
+
+ return 0;
+}
+
+static inline struct hmm *hmm_ref(struct hmm *hmm)
+{
+ if (!hmm || !kref_get_unless_zero(&hmm->kref))
+ return NULL;
+ return hmm;
+}
+
+static void hmm_destroy(struct kref *kref)
+{
+ struct hmm *hmm;
+
+ hmm = container_of(kref, struct hmm, kref);
+ BUG_ON(!hlist_empty(&hmm->mirrors));
+
+ down_write(&hmm->mm->mmap_sem);
+ /* A new hmm might have been register before reaching that point. */
+ if (hmm->mm->hmm == hmm)
+ hmm->mm->hmm = NULL;
+ up_write(&hmm->mm->mmap_sem);
+
+ mmu_notifier_unregister(&hmm->mmu_notifier, hmm->mm);
+
+ kfree(hmm);
+}
+
+static inline struct hmm *hmm_unref(struct hmm *hmm)
+{
+ if (hmm)
+ kref_put(&hmm->kref, hmm_destroy);
+ return NULL;
+}
+
+
+/* hmm_notifier - HMM callback for mmu_notifier tracking change to process mm.
+ *
+ * HMM use use mmu notifier to track change made to process address space.
+ */
+static void hmm_notifier_release(struct mmu_notifier *mn, struct mm_struct *mm)
+{
+ struct hmm *hmm;
+ int id;
+
+ /*
+ * The hmm structure can not be free because the mmu_notifier srcu is
+ * read locked thus any concurrent hmm_mirror_unregister that would
+ * free hmm would have to wait on the mmu_notifier srcu.
+ */
+ hmm = container_of(mn, struct hmm, mmu_notifier);
+
+ id = srcu_read_lock(&srcu);
+ spin_lock(&hmm->lock);
+ while (hmm->mirrors.first) {
+ struct hmm_mirror *mirror;
+
+ mirror = hlist_entry(hmm->mirrors.first,
+ struct hmm_mirror,
+ mlist);
+ hlist_del_init_rcu(&mirror->mlist);
+ spin_unlock(&hmm->lock);
+
+ mirror->device->ops->release(mirror);
+
+ mutex_lock(&mirror->device->mutex);
+ list_del_init(&mirror->dlist);
+ mutex_unlock(&mirror->device->mutex);
+
+ spin_lock(&hmm->lock);
+ }
+ spin_unlock(&hmm->lock);
+
+ srcu_read_unlock(&srcu, id);
+}
+
+static struct mmu_notifier_ops hmm_notifier_ops = {
+ .release = hmm_notifier_release,
+};
+
+
+/* hmm_mirror - per device mirroring functions.
+ *
+ * Each device that mirror a process has a uniq hmm_mirror struct. A process
+ * can be mirror by several devices at the same time.
+ *
+ * Below are all the functions and their helpers use by device driver to mirror
+ * the process address space. Those functions either deals with updating the
+ * device page table (through hmm callback). Or provide helper functions use by
+ * the device driver to fault in range of memory in the device page table.
+ */
+
+/* hmm_mirror_register() - register mirror against current process for a device.
+ *
+ * @mirror: The mirror struct being registered.
+ * @device: The device struct to against which the mirror is registered.
+ * Returns: 0 on success or -ENOMEM, -EINVAL on error.
+ *
+ * Call when device driver want to start mirroring a process address space. The
+ * HMM shim will register mmu_notifier and start monitoring process address
+ * space changes. Hence callback to device driver might happen even before this
+ * function return.
+ *
+ * The task device driver want to mirror must be current !
+ *
+ * Only one mirror per mm and hmm_device can be created, it will return NULL if
+ * the hmm_device already has an hmm_mirror for the the mm.
+ */
+int hmm_mirror_register(struct hmm_mirror *mirror, struct hmm_device *device)
+{
+ struct mm_struct *mm = current->mm;
+ struct hmm *hmm = NULL;
+ int ret = 0;
+
+ /* Sanity checks. */
+ BUG_ON(!device);
+ BUG_ON(!mm);
+
+ /*
+ * Initialize the mirror struct fields, the mlist init and del dance is
+ * necessary to make the error path easier for driver and for hmm.
+ */
+ INIT_HLIST_NODE(&mirror->mlist);
+ INIT_LIST_HEAD(&mirror->dlist);
+ mutex_lock(&device->mutex);
+ mirror->device = device;
+ list_add(&mirror->dlist, &device->mirrors);
+ mutex_unlock(&device->mutex);
+
+ down_write(&mm->mmap_sem);
+
+ hmm = mm->hmm ? hmm_ref(hmm) : NULL;
+ if (hmm == NULL) {
+ /* no hmm registered yet so register one */
+ hmm = kzalloc(sizeof(*mm->hmm), GFP_KERNEL);
+ if (hmm == NULL) {
+ up_write(&mm->mmap_sem);
+ ret = -ENOMEM;
+ goto error;
+ }
+
+ ret = hmm_init(hmm);
+ if (ret) {
+ up_write(&mm->mmap_sem);
+ kfree(hmm);
+ goto error;
+ }
+
+ mm->hmm = hmm;
+ }
+
+ mirror->hmm = hmm;
+ ret = hmm_add_mirror(hmm, mirror);
+ up_write(&mm->mmap_sem);
+ if (ret) {
+ mirror->hmm = NULL;
+ hmm_unref(hmm);
+ goto error;
+ }
+ return 0;
+
+error:
+ mutex_lock(&device->mutex);
+ list_del_init(&mirror->dlist);
+ mutex_unlock(&device->mutex);
+ return ret;
+}
+EXPORT_SYMBOL(hmm_mirror_register);
+
+static void hmm_mirror_release(struct hmm_mirror *mirror)
+{
+ spin_lock(&mirror->hmm->lock);
+ if (!hlist_unhashed(&mirror->mlist)) {
+ hlist_del_init_rcu(&mirror->mlist);
+ spin_unlock(&mirror->hmm->lock);
+ mirror->device->ops->release(mirror);
+
+ mutex_lock(&mirror->device->mutex);
+ list_del_init(&mirror->dlist);
+ mutex_unlock(&mirror->device->mutex);
+ } else
+ spin_unlock(&mirror->hmm->lock);
+}
+
+/* hmm_mirror_unregister() - unregister a mirror.
+ *
+ * @mirror: The mirror that link process address space with the device.
+ *
+ * Driver can call this function when it wants to stop mirroring a process.
+ * This will trigger a call to the ->stop() callback if it did not aleady
+ * happen.
+ */
+void hmm_mirror_unregister(struct hmm_mirror *mirror)
+{
+ int id;
+
+ id = srcu_read_lock(&srcu);
+ hmm_mirror_release(mirror);
+ srcu_read_unlock(&srcu, id);
+
+ /*
+ * Wait for any running method to finish, of course including
+ * ->release() if it was run by hmm_notifier_release instead of us.
+ */
+ synchronize_srcu(&srcu);
+
+ mirror->hmm = hmm_unref(mirror->hmm);
+}
+EXPORT_SYMBOL(hmm_mirror_unregister);
+
+
+/* hmm_device - Each device driver must register one and only one hmm_device
+ *
+ * The hmm_device is the link btw HMM and each device driver.
+ */
+
+/* hmm_device_register() - register a device with HMM.
+ *
+ * @device: The hmm_device struct.
+ * Returns: 0 on success or -EINVAL otherwise.
+ *
+ *
+ * Call when device driver want to register itself with HMM. Device driver must
+ * only register once.
+ */
+int hmm_device_register(struct hmm_device *device)
+{
+ /* sanity check */
+ BUG_ON(!device);
+ BUG_ON(!device->name);
+ BUG_ON(!device->ops);
+ BUG_ON(!device->ops->release);
+
+ mutex_init(&device->mutex);
+ INIT_LIST_HEAD(&device->mirrors);
+
+ return 0;
+}
+EXPORT_SYMBOL(hmm_device_register);
+
+/* hmm_device_unregister() - unregister a device with HMM.
+ *
+ * @device: The hmm_device struct.
+ * Returns: 0 on success or -EBUSY otherwise.
+ *
+ * Call when device driver want to unregister itself with HMM. This will check
+ * that there is no any active mirror and returns -EBUSY if so.
+ */
+int hmm_device_unregister(struct hmm_device *device)
+{
+ mutex_lock(&device->mutex);
+ if (!list_empty(&device->mirrors)) {
+ mutex_unlock(&device->mutex);
+ return -EBUSY;
+ }
+ mutex_unlock(&device->mutex);
+ synchronize_srcu(&srcu);
+ return 0;
+}
+EXPORT_SYMBOL(hmm_device_unregister);
+
+
+static int __init hmm_subsys_init(void)
+{
+ return init_srcu_struct(&srcu);
+}
+subsys_initcall(hmm_subsys_init);
--
1.9.3
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxx. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>