1// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
2/*
3 * Copyright(c) 2015-2017 Intel Corporation.
4 */
5
6#include <linux/mm.h>
7#include <linux/sched/signal.h>
8#include <linux/device.h>
9#include <linux/module.h>
10
11#include "hfi.h"
12
13static unsigned long cache_size = 256;
14module_param(cache_size, ulong, S_IRUGO | S_IWUSR);
15MODULE_PARM_DESC(cache_size, "Send and receive side cache size limit (in MB)");
16
17/*
18 * Determine whether the caller can pin pages.
19 *
20 * This function should be used in the implementation of buffer caches.
21 * The cache implementation should call this function prior to attempting
22 * to pin buffer pages in order to determine whether they should do so.
23 * The function computes cache limits based on the configured ulimit and
24 * cache size. Use of this function is especially important for caches
25 * which are not limited in any other way (e.g. by HW resources) and, thus,
26 * could keeping caching buffers.
27 *
28 */
29bool hfi1_can_pin_pages(struct hfi1_devdata *dd, struct mm_struct *mm,
30 u32 nlocked, u32 npages)
31{
32 unsigned long ulimit_pages;
33 unsigned long cache_limit_pages;
34 unsigned int usr_ctxts;
35
36 /*
37 * Perform RLIMIT_MEMLOCK based checks unless CAP_IPC_LOCK is present.
38 */
39 if (!capable(CAP_IPC_LOCK)) {
40 ulimit_pages =
41 DIV_ROUND_DOWN_ULL(rlimit(RLIMIT_MEMLOCK), PAGE_SIZE);
42
43 /*
44 * Pinning these pages would exceed this process's locked memory
45 * limit.
46 */
47 if (atomic64_read(v: &mm->pinned_vm) + npages > ulimit_pages)
48 return false;
49
50 /*
51 * Only allow 1/4 of the user's RLIMIT_MEMLOCK to be used for HFI
52 * caches. This fraction is then equally distributed among all
53 * existing user contexts. Note that if RLIMIT_MEMLOCK is
54 * 'unlimited' (-1), the value of this limit will be > 2^42 pages
55 * (2^64 / 2^12 / 2^8 / 2^2).
56 *
57 * The effectiveness of this check may be reduced if I/O occurs on
58 * some user contexts before all user contexts are created. This
59 * check assumes that this process is the only one using this
60 * context (e.g., the corresponding fd was not passed to another
61 * process for concurrent access) as there is no per-context,
62 * per-process tracking of pinned pages. It also assumes that each
63 * user context has only one cache to limit.
64 */
65 usr_ctxts = dd->num_rcv_contexts - dd->first_dyn_alloc_ctxt;
66 if (nlocked + npages > (ulimit_pages / usr_ctxts / 4))
67 return false;
68 }
69
70 /*
71 * Pinning these pages would exceed the size limit for this cache.
72 */
73 cache_limit_pages = cache_size * (1024 * 1024) / PAGE_SIZE;
74 if (nlocked + npages > cache_limit_pages)
75 return false;
76
77 return true;
78}
79
80int hfi1_acquire_user_pages(struct mm_struct *mm, unsigned long vaddr, size_t npages,
81 bool writable, struct page **pages)
82{
83 int ret;
84 unsigned int gup_flags = FOLL_LONGTERM | (writable ? FOLL_WRITE : 0);
85
86 ret = pin_user_pages_fast(start: vaddr, nr_pages: npages, gup_flags, pages);
87 if (ret < 0)
88 return ret;
89
90 atomic64_add(i: ret, v: &mm->pinned_vm);
91
92 return ret;
93}
94
95void hfi1_release_user_pages(struct mm_struct *mm, struct page **p,
96 size_t npages, bool dirty)
97{
98 unpin_user_pages_dirty_lock(pages: p, npages, make_dirty: dirty);
99
100 if (mm) { /* during close after signal, mm can be NULL */
101 atomic64_sub(i: npages, v: &mm->pinned_vm);
102 }
103}
104

source code of linux/drivers/infiniband/hw/hfi1/user_pages.c