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Diffstat (limited to 'include/linux/hmm.h')
| -rw-r--r-- | include/linux/hmm.h | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/include/linux/hmm.h b/include/linux/hmm.h new file mode 100644 index 000000000..126a36571 --- /dev/null +++ b/include/linux/hmm.h @@ -0,0 +1,116 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copyright 2013 Red Hat Inc. + * + * Authors: Jérôme Glisse <jglisse@redhat.com> + * + * See Documentation/mm/hmm.rst for reasons and overview of what HMM is. + */ +#ifndef LINUX_HMM_H +#define LINUX_HMM_H + +#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 + * + * 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), + 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_to_page() - return struct page pointed to by a device entry + * + * 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 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 + * + * @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 + */ +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; +}; + +/* + * Please see Documentation/mm/hmm.rst for how to use the range API. + */ +int hmm_range_fault(struct hmm_range *range); + +/* + * 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 potentially wait for ever, 1000ms ie 1s sounds like a long time to + * wait already. + */ +#define HMM_RANGE_DEFAULT_TIMEOUT 1000 + +#endif /* LINUX_HMM_H */ |