From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/include/linux/hmm.h | 599 +++++++----------------------------------------------------
1 files changed, 79 insertions(+), 520 deletions(-)
diff --git a/kernel/include/linux/hmm.h b/kernel/include/linux/hmm.h
index 5ec8635..866a0fa 100644
--- a/kernel/include/linux/hmm.h
+++ b/kernel/include/linux/hmm.h
@@ -1,562 +1,121 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* 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.
+ * Authors: Jérôme Glisse <jglisse@redhat.com>
*
- * 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@redhat.com>
- */
-/*
- * Heterogeneous Memory Management (HMM)
- *
- * See Documentation/vm/hmm.rst for reasons and overview of what HMM is and it
- * is for. Here we focus on the HMM API description, with some explanation of
- * the underlying implementation.
- *
- * Short description: HMM provides a set of helpers to share a virtual address
- * space between CPU and a device, so that the device can access any valid
- * address of the process (while still obeying memory protection). HMM also
- * provides helpers to migrate process memory to device memory, and back. Each
- * set of functionality (address space mirroring, and migration to and from
- * device memory) can be used independently of the other.
- *
- *
- * HMM address space mirroring API:
- *
- * Use HMM address space mirroring if you want to mirror range of the CPU page
- * table of a process into a device page table. Here, "mirror" means "keep
- * synchronized". Prerequisites: the device must provide the ability to write-
- * protect its page tables (at PAGE_SIZE granularity), and must be able to
- * recover from the resulting potential page faults.
- *
- * HMM guarantees that at any point in time, a given virtual address points to
- * either the same memory in both CPU and device page tables (that is: CPU and
- * device page tables each point to the same pages), or that one page table (CPU
- * or device) points to no entry, while the other still points to the old page
- * for the address. The latter case happens when the CPU page table update
- * happens first, and then the update is mirrored over to the device page table.
- * This does not cause any issue, because the CPU page table cannot start
- * pointing to a new page until the device page table is invalidated.
- *
- * HMM uses mmu_notifiers to monitor the CPU page tables, and forwards any
- * updates to each device driver that has registered a mirror. It also provides
- * some API calls to help with taking a snapshot of the CPU page table, and to
- * synchronize with any updates that might happen concurrently.
- *
- *
- * HMM migration to and from device memory:
- *
- * HMM provides a set of helpers to hotplug device memory as ZONE_DEVICE, with
- * a new MEMORY_DEVICE_PRIVATE type. This provides a struct page for each page
- * of the device memory, and allows the device driver to manage its memory
- * using those struct pages. Having struct pages for device memory makes
- * migration easier. Because that memory is not addressable by the CPU it must
- * never be pinned to the device; in other words, any CPU page fault can always
- * cause the device memory to be migrated (copied/moved) back to regular memory.
- *
- * A new migrate helper (migrate_vma()) has been added (see mm/migrate.c) that
- * allows use of a device DMA engine to perform the copy operation between
- * regular system memory and device memory.
+ * See Documentation/vm/hmm.rst for reasons and overview of what HMM is.
*/
#ifndef LINUX_HMM_H
#define LINUX_HMM_H
#include <linux/kconfig.h>
-
-#if IS_ENABLED(CONFIG_HMM)
+#include <linux/pgtable.h>
#include <linux/device.h>
#include <linux/migrate.h>
#include <linux/memremap.h>
#include <linux/completion.h>
-
-struct hmm;
+#include <linux/mmu_notifier.h>
/*
- * hmm_pfn_flag_e - HMM flag enums
+ * On output:
+ * 0 - The page is faultable and a future call with
+ * HMM_PFN_REQ_FAULT could succeed.
+ * HMM_PFN_VALID - the pfn field points to a valid PFN. This PFN is at
+ * least readable. If dev_private_owner is !NULL then this could
+ * point at a DEVICE_PRIVATE page.
+ * HMM_PFN_WRITE - if the page memory can be written to (requires HMM_PFN_VALID)
+ * HMM_PFN_ERROR - accessing the pfn is impossible and the device should
+ * fail. ie poisoned memory, special pages, no vma, etc
*
- * Flags:
- * HMM_PFN_VALID: pfn is valid. It has, at least, read permission.
- * HMM_PFN_WRITE: CPU page table has write permission set
- * HMM_PFN_DEVICE_PRIVATE: private device memory (ZONE_DEVICE)
- *
- * The driver provide a flags array, if driver valid bit for an entry is bit
- * 3 ie (entry & (1 << 3)) is true if entry is valid then driver must provide
- * an array in hmm_range.flags with hmm_range.flags[HMM_PFN_VALID] == 1 << 3.
- * Same logic apply to all flags. This is same idea as vm_page_prot in vma
- * except that this is per device driver rather than per architecture.
+ * On input:
+ * 0 - Return the current state of the page, do not fault it.
+ * HMM_PFN_REQ_FAULT - The output must have HMM_PFN_VALID or hmm_range_fault()
+ * will fail
+ * HMM_PFN_REQ_WRITE - The output must have HMM_PFN_WRITE or hmm_range_fault()
+ * will fail. Must be combined with HMM_PFN_REQ_FAULT.
*/
-enum hmm_pfn_flag_e {
- HMM_PFN_VALID = 0,
- HMM_PFN_WRITE,
- HMM_PFN_DEVICE_PRIVATE,
- HMM_PFN_FLAG_MAX
+enum hmm_pfn_flags {
+ /* Output fields and flags */
+ HMM_PFN_VALID = 1UL << (BITS_PER_LONG - 1),
+ HMM_PFN_WRITE = 1UL << (BITS_PER_LONG - 2),
+ HMM_PFN_ERROR = 1UL << (BITS_PER_LONG - 3),
+ HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 8),
+
+ /* Input flags */
+ HMM_PFN_REQ_FAULT = HMM_PFN_VALID,
+ HMM_PFN_REQ_WRITE = HMM_PFN_WRITE,
+
+ HMM_PFN_FLAGS = 0xFFUL << HMM_PFN_ORDER_SHIFT,
};
/*
- * hmm_pfn_value_e - HMM pfn special value
+ * hmm_pfn_to_page() - return struct page pointed to by a device entry
*
- * Flags:
- * HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory
- * HMM_PFN_NONE: corresponding CPU page table entry is pte_none()
- * HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., the
- * result of vm_insert_pfn() or vm_insert_page(). Therefore, it should not
- * be mirrored by a device, because the entry will never have HMM_PFN_VALID
- * set and the pfn value is undefined.
- *
- * Driver provide entry value for none entry, error entry and special entry,
- * driver can alias (ie use same value for error and special for instance). It
- * should not alias none and error or special.
- *
- * HMM pfn value returned by hmm_vma_get_pfns() or hmm_vma_fault() will be:
- * hmm_range.values[HMM_PFN_ERROR] if CPU page table entry is poisonous,
- * hmm_range.values[HMM_PFN_NONE] if there is no CPU page table
- * hmm_range.values[HMM_PFN_SPECIAL] if CPU page table entry is a special one
+ * This must be called under the caller 'user_lock' after a successful
+ * mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID
+ * already.
*/
-enum hmm_pfn_value_e {
- HMM_PFN_ERROR,
- HMM_PFN_NONE,
- HMM_PFN_SPECIAL,
- HMM_PFN_VALUE_MAX
-};
+static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn)
+{
+ return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS);
+}
+
+/*
+ * hmm_pfn_to_map_order() - return the CPU mapping size order
+ *
+ * This is optionally useful to optimize processing of the pfn result
+ * array. It indicates that the page starts at the order aligned VA and is
+ * 1<<order bytes long. Every pfn within an high order page will have the
+ * same pfn flags, both access protections and the map_order. The caller must
+ * be careful with edge cases as the start and end VA of the given page may
+ * extend past the range used with hmm_range_fault().
+ *
+ * This must be called under the caller 'user_lock' after a successful
+ * mmu_interval_read_begin(). The caller must have tested for HMM_PFN_VALID
+ * already.
+ */
+static inline unsigned int hmm_pfn_to_map_order(unsigned long hmm_pfn)
+{
+ return (hmm_pfn >> HMM_PFN_ORDER_SHIFT) & 0x1F;
+}
/*
* struct hmm_range - track invalidation lock on virtual address range
*
- * @vma: the vm area struct for the range
- * @list: all range lock are on a list
+ * @notifier: a mmu_interval_notifier that includes the start/end
+ * @notifier_seq: result of mmu_interval_read_begin()
* @start: range virtual start address (inclusive)
* @end: range virtual end address (exclusive)
- * @pfns: array of pfns (big enough for the range)
- * @flags: pfn flags to match device driver page table
- * @values: pfn value for some special case (none, special, error, ...)
- * @pfn_shifts: pfn shift value (should be <= PAGE_SHIFT)
- * @valid: pfns array did not change since it has been fill by an HMM function
+ * @hmm_pfns: array of pfns (big enough for the range)
+ * @default_flags: default flags for the range (write, read, ... see hmm doc)
+ * @pfn_flags_mask: allows to mask pfn flags so that only default_flags matter
+ * @dev_private_owner: owner of device private pages
*/
struct hmm_range {
- struct vm_area_struct *vma;
- struct list_head list;
+ struct mmu_interval_notifier *notifier;
+ unsigned long notifier_seq;
unsigned long start;
unsigned long end;
- uint64_t *pfns;
- const uint64_t *flags;
- const uint64_t *values;
- uint8_t pfn_shift;
- bool valid;
+ unsigned long *hmm_pfns;
+ unsigned long default_flags;
+ unsigned long pfn_flags_mask;
+ void *dev_private_owner;
};
/*
- * hmm_pfn_to_page() - return struct page pointed to by a valid HMM pfn
- * @range: range use to decode HMM pfn value
- * @pfn: HMM pfn value to get corresponding struct page from
- * Returns: struct page pointer if pfn is a valid HMM pfn, NULL otherwise
- *
- * If the HMM pfn is valid (ie valid flag set) then return the struct page
- * matching the pfn value stored in the HMM pfn. Otherwise return NULL.
+ * Please see Documentation/vm/hmm.rst for how to use the range API.
*/
-static inline struct page *hmm_pfn_to_page(const struct hmm_range *range,
- uint64_t pfn)
-{
- if (pfn == range->values[HMM_PFN_NONE])
- return NULL;
- if (pfn == range->values[HMM_PFN_ERROR])
- return NULL;
- if (pfn == range->values[HMM_PFN_SPECIAL])
- return NULL;
- if (!(pfn & range->flags[HMM_PFN_VALID]))
- return NULL;
- return pfn_to_page(pfn >> range->pfn_shift);
-}
+int hmm_range_fault(struct hmm_range *range);
/*
- * hmm_pfn_to_pfn() - return pfn value store in a HMM pfn
- * @range: range use to decode HMM pfn value
- * @pfn: HMM pfn value to extract pfn from
- * Returns: pfn value if HMM pfn is valid, -1UL otherwise
+ * HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range
+ *
+ * When waiting for mmu notifiers we need some kind of time out otherwise we
+ * could potentialy wait for ever, 1000ms ie 1s sounds like a long time to
+ * wait already.
*/
-static inline unsigned long hmm_pfn_to_pfn(const struct hmm_range *range,
- uint64_t pfn)
-{
- if (pfn == range->values[HMM_PFN_NONE])
- return -1UL;
- if (pfn == range->values[HMM_PFN_ERROR])
- return -1UL;
- if (pfn == range->values[HMM_PFN_SPECIAL])
- return -1UL;
- if (!(pfn & range->flags[HMM_PFN_VALID]))
- return -1UL;
- return (pfn >> range->pfn_shift);
-}
-
-/*
- * hmm_pfn_from_page() - create a valid HMM pfn value from struct page
- * @range: range use to encode HMM pfn value
- * @page: struct page pointer for which to create the HMM pfn
- * Returns: valid HMM pfn for the page
- */
-static inline uint64_t hmm_pfn_from_page(const struct hmm_range *range,
- struct page *page)
-{
- return (page_to_pfn(page) << range->pfn_shift) |
- range->flags[HMM_PFN_VALID];
-}
-
-/*
- * hmm_pfn_from_pfn() - create a valid HMM pfn value from pfn
- * @range: range use to encode HMM pfn value
- * @pfn: pfn value for which to create the HMM pfn
- * Returns: valid HMM pfn for the pfn
- */
-static inline uint64_t hmm_pfn_from_pfn(const struct hmm_range *range,
- unsigned long pfn)
-{
- return (pfn << range->pfn_shift) |
- range->flags[HMM_PFN_VALID];
-}
-
-
-#if IS_ENABLED(CONFIG_HMM_MIRROR)
-/*
- * Mirroring: how to synchronize device page table with CPU page table.
- *
- * A device driver that is participating in HMM mirroring must always
- * synchronize with CPU page table updates. For this, device drivers can either
- * directly use mmu_notifier APIs or they can use the hmm_mirror API. Device
- * drivers can decide to register one mirror per device per process, or just
- * one mirror per process for a group of devices. The pattern is:
- *
- * int device_bind_address_space(..., struct mm_struct *mm, ...)
- * {
- * struct device_address_space *das;
- *
- * // Device driver specific initialization, and allocation of das
- * // which contains an hmm_mirror struct as one of its fields.
- * ...
- *
- * ret = hmm_mirror_register(&das->mirror, mm, &device_mirror_ops);
- * if (ret) {
- * // Cleanup on error
- * return ret;
- * }
- *
- * // Other device driver specific initialization
- * ...
- * }
- *
- * Once an hmm_mirror is registered for an address space, the device driver
- * will get callbacks through sync_cpu_device_pagetables() operation (see
- * hmm_mirror_ops struct).
- *
- * Device driver must not free the struct containing the hmm_mirror struct
- * before calling hmm_mirror_unregister(). The expected usage is to do that when
- * the device driver is unbinding from an address space.
- *
- *
- * void device_unbind_address_space(struct device_address_space *das)
- * {
- * // Device driver specific cleanup
- * ...
- *
- * hmm_mirror_unregister(&das->mirror);
- *
- * // Other device driver specific cleanup, and now das can be freed
- * ...
- * }
- */
-
-struct hmm_mirror;
-
-/*
- * enum hmm_update_type - type of update
- * @HMM_UPDATE_INVALIDATE: invalidate range (no indication as to why)
- */
-enum hmm_update_type {
- HMM_UPDATE_INVALIDATE,
-};
-
-/*
- * struct hmm_mirror_ops - HMM mirror device operations callback
- *
- * @update: callback to update range on a device
- */
-struct hmm_mirror_ops {
- /* release() - release hmm_mirror
- *
- * @mirror: pointer to struct hmm_mirror
- *
- * This is called when the mm_struct is being released.
- * The callback should make sure no references to the mirror occur
- * after the callback returns.
- */
- void (*release)(struct hmm_mirror *mirror);
-
- /* sync_cpu_device_pagetables() - synchronize page tables
- *
- * @mirror: pointer to struct hmm_mirror
- * @update_type: type of update that occurred to the CPU page table
- * @start: virtual start address of the range to update
- * @end: virtual end address of the range to update
- *
- * This callback ultimately originates from mmu_notifiers when the CPU
- * page table is updated. The device driver must update its page table
- * in response to this callback. The update argument tells what action
- * to perform.
- *
- * The device driver must not return from this callback until the device
- * page tables are completely updated (TLBs flushed, etc); this is a
- * synchronous call.
- */
- void (*sync_cpu_device_pagetables)(struct hmm_mirror *mirror,
- enum hmm_update_type update_type,
- unsigned long start,
- unsigned long end);
-};
-
-/*
- * struct hmm_mirror - mirror struct for a device driver
- *
- * @hmm: pointer to struct hmm (which is unique per mm_struct)
- * @ops: device driver callback for HMM mirror operations
- * @list: for list of mirrors of a given mm
- *
- * Each address space (mm_struct) being mirrored by a device must register one
- * instance of an hmm_mirror struct with HMM. HMM will track the list of all
- * mirrors for each mm_struct.
- */
-struct hmm_mirror {
- struct hmm *hmm;
- const struct hmm_mirror_ops *ops;
- struct list_head list;
-};
-
-int hmm_mirror_register(struct hmm_mirror *mirror, struct mm_struct *mm);
-void hmm_mirror_unregister(struct hmm_mirror *mirror);
-
-
-/*
- * To snapshot the CPU page table, call hmm_vma_get_pfns(), then take a device
- * driver lock that serializes device page table updates, then call
- * hmm_vma_range_done(), to check if the snapshot is still valid. The same
- * device driver page table update lock must also be used in the
- * hmm_mirror_ops.sync_cpu_device_pagetables() callback, so that CPU page
- * table invalidation serializes on it.
- *
- * YOU MUST CALL hmm_vma_range_done() ONCE AND ONLY ONCE EACH TIME YOU CALL
- * hmm_vma_get_pfns() WITHOUT ERROR !
- *
- * IF YOU DO NOT FOLLOW THE ABOVE RULE THE SNAPSHOT CONTENT MIGHT BE INVALID !
- */
-int hmm_vma_get_pfns(struct hmm_range *range);
-bool hmm_vma_range_done(struct hmm_range *range);
-
-
-/*
- * Fault memory on behalf of device driver. Unlike handle_mm_fault(), this will
- * not migrate any device memory back to system memory. The HMM pfn array will
- * be updated with the fault result and current snapshot of the CPU page table
- * for the range.
- *
- * The mmap_sem must be taken in read mode before entering and it might be
- * dropped by the function if the block argument is false. In that case, the
- * function returns -EAGAIN.
- *
- * Return value does not reflect if the fault was successful for every single
- * address or not. Therefore, the caller must to inspect the HMM pfn array to
- * determine fault status for each address.
- *
- * Trying to fault inside an invalid vma will result in -EINVAL.
- *
- * See the function description in mm/hmm.c for further documentation.
- */
-int hmm_vma_fault(struct hmm_range *range, bool block);
-
-/* Below are for HMM internal use only! Not to be used by device driver! */
-void hmm_mm_destroy(struct mm_struct *mm);
-
-static inline void hmm_mm_init(struct mm_struct *mm)
-{
- mm->hmm = NULL;
-}
-#else /* IS_ENABLED(CONFIG_HMM_MIRROR) */
-static inline void hmm_mm_destroy(struct mm_struct *mm) {}
-static inline void hmm_mm_init(struct mm_struct *mm) {}
-#endif /* IS_ENABLED(CONFIG_HMM_MIRROR) */
-
-#if IS_ENABLED(CONFIG_DEVICE_PRIVATE) || IS_ENABLED(CONFIG_DEVICE_PUBLIC)
-struct hmm_devmem;
-
-struct page *hmm_vma_alloc_locked_page(struct vm_area_struct *vma,
- unsigned long addr);
-
-/*
- * struct hmm_devmem_ops - callback for ZONE_DEVICE memory events
- *
- * @free: call when refcount on page reach 1 and thus is no longer use
- * @fault: call when there is a page fault to unaddressable memory
- *
- * Both callback happens from page_free() and page_fault() callback of struct
- * dev_pagemap respectively. See include/linux/memremap.h for more details on
- * those.
- *
- * The hmm_devmem_ops callback are just here to provide a coherent and
- * uniq API to device driver and device driver should not register their
- * own page_free() or page_fault() but rely on the hmm_devmem_ops call-
- * back.
- */
-struct hmm_devmem_ops {
- /*
- * free() - free a device page
- * @devmem: device memory structure (see struct hmm_devmem)
- * @page: pointer to struct page being freed
- *
- * Call back occurs whenever a device page refcount reach 1 which
- * means that no one is holding any reference on the page anymore
- * (ZONE_DEVICE page have an elevated refcount of 1 as default so
- * that they are not release to the general page allocator).
- *
- * Note that callback has exclusive ownership of the page (as no
- * one is holding any reference).
- */
- void (*free)(struct hmm_devmem *devmem, struct page *page);
- /*
- * fault() - CPU page fault or get user page (GUP)
- * @devmem: device memory structure (see struct hmm_devmem)
- * @vma: virtual memory area containing the virtual address
- * @addr: virtual address that faulted or for which there is a GUP
- * @page: pointer to struct page backing virtual address (unreliable)
- * @flags: FAULT_FLAG_* (see include/linux/mm.h)
- * @pmdp: page middle directory
- * Returns: VM_FAULT_MINOR/MAJOR on success or one of VM_FAULT_ERROR
- * on error
- *
- * The callback occurs whenever there is a CPU page fault or GUP on a
- * virtual address. This means that the device driver must migrate the
- * page back to regular memory (CPU accessible).
- *
- * The device driver is free to migrate more than one page from the
- * fault() callback as an optimization. However if device decide to
- * migrate more than one page it must always priotirize the faulting
- * address over the others.
- *
- * The struct page pointer is only given as an hint to allow quick
- * lookup of internal device driver data. A concurrent migration
- * might have already free that page and the virtual address might
- * not longer be back by it. So it should not be modified by the
- * callback.
- *
- * Note that mmap semaphore is held in read mode at least when this
- * callback occurs, hence the vma is valid upon callback entry.
- */
- int (*fault)(struct hmm_devmem *devmem,
- struct vm_area_struct *vma,
- unsigned long addr,
- const struct page *page,
- unsigned int flags,
- pmd_t *pmdp);
-};
-
-/*
- * struct hmm_devmem - track device memory
- *
- * @completion: completion object for device memory
- * @pfn_first: first pfn for this resource (set by hmm_devmem_add())
- * @pfn_last: last pfn for this resource (set by hmm_devmem_add())
- * @resource: IO resource reserved for this chunk of memory
- * @pagemap: device page map for that chunk
- * @device: device to bind resource to
- * @ops: memory operations callback
- * @ref: per CPU refcount
- *
- * This an helper structure for device drivers that do not wish to implement
- * the gory details related to hotplugging new memoy and allocating struct
- * pages.
- *
- * Device drivers can directly use ZONE_DEVICE memory on their own if they
- * wish to do so.
- */
-struct hmm_devmem {
- struct completion completion;
- unsigned long pfn_first;
- unsigned long pfn_last;
- struct resource *resource;
- struct device *device;
- struct dev_pagemap pagemap;
- const struct hmm_devmem_ops *ops;
- struct percpu_ref ref;
-};
-
-/*
- * To add (hotplug) device memory, HMM assumes that there is no real resource
- * that reserves a range in the physical address space (this is intended to be
- * use by unaddressable device memory). It will reserve a physical range big
- * enough and allocate struct page for it.
- *
- * The device driver can wrap the hmm_devmem struct inside a private device
- * driver struct.
- */
-struct hmm_devmem *hmm_devmem_add(const struct hmm_devmem_ops *ops,
- struct device *device,
- unsigned long size);
-struct hmm_devmem *hmm_devmem_add_resource(const struct hmm_devmem_ops *ops,
- struct device *device,
- struct resource *res);
-
-/*
- * hmm_devmem_page_set_drvdata - set per-page driver data field
- *
- * @page: pointer to struct page
- * @data: driver data value to set
- *
- * Because page can not be on lru we have an unsigned long that driver can use
- * to store a per page field. This just a simple helper to do that.
- */
-static inline void hmm_devmem_page_set_drvdata(struct page *page,
- unsigned long data)
-{
- page->hmm_data = data;
-}
-
-/*
- * hmm_devmem_page_get_drvdata - get per page driver data field
- *
- * @page: pointer to struct page
- * Return: driver data value
- */
-static inline unsigned long hmm_devmem_page_get_drvdata(const struct page *page)
-{
- return page->hmm_data;
-}
-
-
-/*
- * struct hmm_device - fake device to hang device memory onto
- *
- * @device: device struct
- * @minor: device minor number
- */
-struct hmm_device {
- struct device device;
- unsigned int minor;
-};
-
-/*
- * A device driver that wants to handle multiple devices memory through a
- * single fake device can use hmm_device to do so. This is purely a helper and
- * it is not strictly needed, in order to make use of any HMM functionality.
- */
-struct hmm_device *hmm_device_new(void *drvdata);
-void hmm_device_put(struct hmm_device *hmm_device);
-#endif /* CONFIG_DEVICE_PRIVATE || CONFIG_DEVICE_PUBLIC */
-#else /* IS_ENABLED(CONFIG_HMM) */
-static inline void hmm_mm_destroy(struct mm_struct *mm) {}
-static inline void hmm_mm_init(struct mm_struct *mm) {}
-#endif /* IS_ENABLED(CONFIG_HMM) */
+#define HMM_RANGE_DEFAULT_TIMEOUT 1000
#endif /* LINUX_HMM_H */
--
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