1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Helpers for IOMMU drivers implementing SVA
4 */
5 #include <linux/mutex.h>
6 #include <linux/sched/mm.h>
7
8 #include "iommu-sva-lib.h"
9
10 static DEFINE_MUTEX(iommu_sva_lock);
11 static DECLARE_IOASID_SET(iommu_sva_pasid);
12
13 /**
14 * iommu_sva_alloc_pasid - Allocate a PASID for the mm
15 * @mm: the mm
16 * @min: minimum PASID value (inclusive)
17 * @max: maximum PASID value (inclusive)
18 *
19 * Try to allocate a PASID for this mm, or take a reference to the existing one
20 * provided it fits within the [@min, @max] range. On success the PASID is
21 * available in mm->pasid, and must be released with iommu_sva_free_pasid().
22 * @min must be greater than 0, because 0 indicates an unused mm->pasid.
23 *
24 * Returns 0 on success and < 0 on error.
25 */
iommu_sva_alloc_pasid(struct mm_struct * mm,ioasid_t min,ioasid_t max)26 int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
27 {
28 int ret = 0;
29 ioasid_t pasid;
30
31 if (min == INVALID_IOASID || max == INVALID_IOASID ||
32 min == 0 || max < min)
33 return -EINVAL;
34
35 mutex_lock(&iommu_sva_lock);
36 if (mm->pasid) {
37 if (mm->pasid >= min && mm->pasid <= max)
38 ioasid_get(mm->pasid);
39 else
40 ret = -EOVERFLOW;
41 } else {
42 pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
43 if (pasid == INVALID_IOASID)
44 ret = -ENOMEM;
45 else
46 mm->pasid = pasid;
47 }
48 mutex_unlock(&iommu_sva_lock);
49 return ret;
50 }
51 EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid);
52
53 /**
54 * iommu_sva_free_pasid - Release the mm's PASID
55 * @mm: the mm
56 *
57 * Drop one reference to a PASID allocated with iommu_sva_alloc_pasid()
58 */
iommu_sva_free_pasid(struct mm_struct * mm)59 void iommu_sva_free_pasid(struct mm_struct *mm)
60 {
61 mutex_lock(&iommu_sva_lock);
62 if (ioasid_put(mm->pasid))
63 mm->pasid = 0;
64 mutex_unlock(&iommu_sva_lock);
65 }
66 EXPORT_SYMBOL_GPL(iommu_sva_free_pasid);
67
68 /* ioasid_find getter() requires a void * argument */
__mmget_not_zero(void * mm)69 static bool __mmget_not_zero(void *mm)
70 {
71 return mmget_not_zero(mm);
72 }
73
74 /**
75 * iommu_sva_find() - Find mm associated to the given PASID
76 * @pasid: Process Address Space ID assigned to the mm
77 *
78 * On success a reference to the mm is taken, and must be released with mmput().
79 *
80 * Returns the mm corresponding to this PASID, or an error if not found.
81 */
iommu_sva_find(ioasid_t pasid)82 struct mm_struct *iommu_sva_find(ioasid_t pasid)
83 {
84 return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
85 }
86 EXPORT_SYMBOL_GPL(iommu_sva_find);
87