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 will be available for the lifetime of the mm.
22  *
23  * Returns 0 on success and < 0 on error.
24  */
iommu_sva_alloc_pasid(struct mm_struct * mm,ioasid_t min,ioasid_t max)25 int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
26 {
27 	int ret = 0;
28 	ioasid_t pasid;
29 
30 	if (min == INVALID_IOASID || max == INVALID_IOASID ||
31 	    min == 0 || max < min)
32 		return -EINVAL;
33 
34 	mutex_lock(&iommu_sva_lock);
35 	/* Is a PASID already associated with this mm? */
36 	if (pasid_valid(mm->pasid)) {
37 		if (mm->pasid < min || mm->pasid >= max)
38 			ret = -EOVERFLOW;
39 		goto out;
40 	}
41 
42 	pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
43 	if (!pasid_valid(pasid))
44 		ret = -ENOMEM;
45 	else
46 		mm_pasid_set(mm, pasid);
47 out:
48 	mutex_unlock(&iommu_sva_lock);
49 	return ret;
50 }
51 EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid);
52 
53 /* ioasid_find getter() requires a void * argument */
__mmget_not_zero(void * mm)54 static bool __mmget_not_zero(void *mm)
55 {
56 	return mmget_not_zero(mm);
57 }
58 
59 /**
60  * iommu_sva_find() - Find mm associated to the given PASID
61  * @pasid: Process Address Space ID assigned to the mm
62  *
63  * On success a reference to the mm is taken, and must be released with mmput().
64  *
65  * Returns the mm corresponding to this PASID, or an error if not found.
66  */
iommu_sva_find(ioasid_t pasid)67 struct mm_struct *iommu_sva_find(ioasid_t pasid)
68 {
69 	return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
70 }
71 EXPORT_SYMBOL_GPL(iommu_sva_find);
72