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Diffstat (limited to 'include/linux/hmm.h')
| -rw-r--r-- | include/linux/hmm.h | 645 |
1 files changed, 91 insertions, 554 deletions
diff --git a/include/linux/hmm.h b/include/linux/hmm.h index 66f9ebbb1df3..db75ffc949a7 100644 --- a/include/linux/hmm.h +++ b/include/linux/hmm.h @@ -1,599 +1,136 @@ +/* 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. - * - * 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/mm/hmm.rst for reasons and overview of what HMM is. */ #ifndef LINUX_HMM_H #define LINUX_HMM_H -#include <linux/kconfig.h> -#include <asm/pgtable.h> - -#if IS_ENABLED(CONFIG_HMM) - -#include <linux/device.h> -#include <linux/migrate.h> -#include <linux/memremap.h> -#include <linux/completion.h> - -struct hmm; +#include <linux/mm.h> + +struct mmu_interval_notifier; + +/* + * 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 + * HMM_PFN_P2PDMA - P2P page + * HMM_PFN_P2PDMA_BUS - Bus mapped P2P transfer + * HMM_PFN_DMA_MAPPED - Flag preserved on input-to-output transformation + * to mark that page is already DMA mapped + * + * 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_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), + /* + * Sticky flags, carried from input to output, + * don't forget to update HMM_PFN_INOUT_FLAGS + */ + HMM_PFN_DMA_MAPPED = 1UL << (BITS_PER_LONG - 4), + HMM_PFN_P2PDMA = 1UL << (BITS_PER_LONG - 5), + HMM_PFN_P2PDMA_BUS = 1UL << (BITS_PER_LONG - 6), -/* - * hmm_pfn_flag_e - HMM flag enums - * - * 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. - */ -enum hmm_pfn_flag_e { - HMM_PFN_VALID = 0, - HMM_PFN_WRITE, - HMM_PFN_DEVICE_PRIVATE, - HMM_PFN_FLAG_MAX -}; + HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 11), -/* - * hmm_pfn_value_e - HMM pfn special value - * - * 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 vmf_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 - */ -enum hmm_pfn_value_e { - HMM_PFN_ERROR, - HMM_PFN_NONE, - HMM_PFN_SPECIAL, - HMM_PFN_VALUE_MAX -}; + /* Input flags */ + HMM_PFN_REQ_FAULT = HMM_PFN_VALID, + HMM_PFN_REQ_WRITE = HMM_PFN_WRITE, -/* - * 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 - * @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 - */ -struct hmm_range { - struct vm_area_struct *vma; - struct list_head list; - unsigned long start; - unsigned long end; - uint64_t *pfns; - const uint64_t *flags; - const uint64_t *values; - uint8_t pfn_shift; - bool valid; + HMM_PFN_FLAGS = ~((1UL << HMM_PFN_ORDER_SHIFT) - 1), }; /* - * 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 + * hmm_pfn_to_page() - return struct page pointed to by a device entry * - * 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. - */ -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); -} - -/* - * 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 - */ -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 + * 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 uint64_t hmm_pfn_from_page(const struct hmm_range *range, - struct page *page) +static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn) { - return (page_to_pfn(page) << range->pfn_shift) | - range->flags[HMM_PFN_VALID]; + return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS); } /* - * 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 + * hmm_pfn_to_phys() - return physical address pointed to by a device entry */ -static inline uint64_t hmm_pfn_from_pfn(const struct hmm_range *range, - unsigned long pfn) +static inline phys_addr_t hmm_pfn_to_phys(unsigned long hmm_pfn) { - return (pfn << range->pfn_shift) | - range->flags[HMM_PFN_VALID]; + return __pfn_to_phys(hmm_pfn & ~HMM_PFN_FLAGS); } - -#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_event - type of update - * @HMM_UPDATE_INVALIDATE: invalidate range (no indication as to why) - */ -enum hmm_update_event { - HMM_UPDATE_INVALIDATE, -}; - -/* - * struct hmm_update - HMM update informations for callback - * - * @start: virtual start address of the range to update - * @end: virtual end address of the range to update - * @event: event triggering the update (what is happening) - * @blockable: can the callback block/sleep ? - */ -struct hmm_update { - unsigned long start; - unsigned long end; - enum hmm_update_event event; - bool blockable; -}; - -/* - * 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: update informations (see struct hmm_update) - * Returns: -EAGAIN if update.blockable false and callback need to - * block, 0 otherwise. - * - * 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. - */ - int (*sync_cpu_device_pagetables)(struct hmm_mirror *mirror, - const struct hmm_update *update); -}; - -/* - * 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. + * hmm_pfn_to_map_order() - return the CPU mapping size order * - * YOU MUST CALL hmm_vma_range_done() ONCE AND ONLY ONCE EACH TIME YOU CALL - * hmm_vma_get_pfns() WITHOUT ERROR ! + * 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(). * - * IF YOU DO NOT FOLLOW THE ABOVE RULE THE SNAPSHOT CONTENT MIGHT BE INVALID ! + * 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. */ -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) +static inline unsigned int hmm_pfn_to_map_order(unsigned long hmm_pfn) { - mm->hmm = NULL; + return (hmm_pfn >> HMM_PFN_ORDER_SHIFT) & 0x1F; } -#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 - * @page_fault: callback when CPU fault on an unaddressable device page - * - * 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. - * - * The page_fault() callback must migrate page back, from device memory to - * system memory, so that the CPU can access it. This might fail for various - * reasons (device issues, device have been unplugged, ...). When such error - * conditions happen, the page_fault() callback must return VM_FAULT_SIGBUS and - * set the CPU page table entry to "poisoned". - * - * Note that because memory cgroup charges are transferred to the device memory, - * this should never fail due to memory restrictions. However, allocation - * of a regular system page might still fail because we are out of memory. If - * that happens, the page_fault() callback must return VM_FAULT_OOM. + * struct hmm_range - track invalidation lock on virtual address range * - * The page_fault() callback can also try to migrate back multiple pages in one - * chunk, as an optimization. It must, however, prioritize the faulting address - * over all the others. + * @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) + * @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 */ -typedef int (*dev_page_fault_t)(struct vm_area_struct *vma, - unsigned long addr, - const struct page *page, - unsigned int flags, - pmd_t *pmdp); - -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; - dev_page_fault_t page_fault; +struct hmm_range { + struct mmu_interval_notifier *notifier; + unsigned long notifier_seq; + unsigned long start; + unsigned long end; + unsigned long *hmm_pfns; + unsigned long default_flags; + unsigned long pfn_flags_mask; + void *dev_private_owner; }; /* - * 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 + * Please see Documentation/mm/hmm.rst for how to use the range API. */ -static inline unsigned long hmm_devmem_page_get_drvdata(const struct page *page) -{ - return page->hmm_data; -} - +int hmm_range_fault(struct hmm_range *range); /* - * struct hmm_device - fake device to hang device memory onto + * HMM_RANGE_DEFAULT_TIMEOUT - default timeout (ms) when waiting for a range * - * @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. + * When waiting for mmu notifiers we need some kind of time out otherwise we + * could potentially wait for ever, 1000ms ie 1s sounds like a long time to + * wait already. */ -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 */ |