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 
13 static unsigned long cache_size = 256;
14 module_param(cache_size, ulong, S_IRUGO | S_IWUSR);
15 MODULE_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  */
hfi1_can_pin_pages(struct hfi1_devdata * dd,struct mm_struct * mm,u32 nlocked,u32 npages)29 bool 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(&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 
hfi1_acquire_user_pages(struct mm_struct * mm,unsigned long vaddr,size_t npages,bool writable,struct page ** pages)80 int 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(vaddr, npages, gup_flags, pages);
87 	if (ret < 0)
88 		return ret;
89 
90 	atomic64_add(ret, &mm->pinned_vm);
91 
92 	return ret;
93 }
94 
hfi1_release_user_pages(struct mm_struct * mm,struct page ** p,size_t npages,bool dirty)95 void hfi1_release_user_pages(struct mm_struct *mm, struct page **p,
96 			     size_t npages, bool dirty)
97 {
98 	unpin_user_pages_dirty_lock(p, npages, dirty);
99 
100 	if (mm) { /* during close after signal, mm can be NULL */
101 		atomic64_sub(npages, &mm->pinned_vm);
102 	}
103 }
104