1 /*
2 * Copyright © 2015 Intel Corporation.
3 *
4 * Authors: David Woodhouse <David.Woodhouse@intel.com>
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms and conditions of the GNU General Public License,
8 * version 2, as published by the Free Software Foundation.
9 *
10 * This program is distributed in the hope it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 */
15
16 #ifndef __INTEL_SVM_H__
17 #define __INTEL_SVM_H__
18
19 struct device;
20
21 struct svm_dev_ops {
22 void (*fault_cb)(struct device *dev, int pasid, u64 address,
23 u32 private, int rwxp, int response);
24 };
25
26 /* Values for rxwp in fault_cb callback */
27 #define SVM_REQ_READ (1<<3)
28 #define SVM_REQ_WRITE (1<<2)
29 #define SVM_REQ_EXEC (1<<1)
30 #define SVM_REQ_PRIV (1<<0)
31
32
33 /*
34 * The SVM_FLAG_PRIVATE_PASID flag requests a PASID which is *not* the "main"
35 * PASID for the current process. Even if a PASID already exists, a new one
36 * will be allocated. And the PASID allocated with SVM_FLAG_PRIVATE_PASID
37 * will not be given to subsequent callers. This facility allows a driver to
38 * disambiguate between multiple device contexts which access the same MM,
39 * if there is no other way to do so. It should be used sparingly, if at all.
40 */
41 #define SVM_FLAG_PRIVATE_PASID (1<<0)
42
43 /*
44 * The SVM_FLAG_SUPERVISOR_MODE flag requests a PASID which can be used only
45 * for access to kernel addresses. No IOTLB flushes are automatically done
46 * for kernel mappings; it is valid only for access to the kernel's static
47 * 1:1 mapping of physical memory — not to vmalloc or even module mappings.
48 * A future API addition may permit the use of such ranges, by means of an
49 * explicit IOTLB flush call (akin to the DMA API's unmap method).
50 *
51 * It is unlikely that we will ever hook into flush_tlb_kernel_range() to
52 * do such IOTLB flushes automatically.
53 */
54 #define SVM_FLAG_SUPERVISOR_MODE (1<<1)
55
56 #ifdef CONFIG_INTEL_IOMMU_SVM
57
58 /**
59 * intel_svm_bind_mm() - Bind the current process to a PASID
60 * @dev: Device to be granted acccess
61 * @pasid: Address for allocated PASID
62 * @flags: Flags. Later for requesting supervisor mode, etc.
63 * @ops: Callbacks to device driver
64 *
65 * This function attempts to enable PASID support for the given device.
66 * If the @pasid argument is non-%NULL, a PASID is allocated for access
67 * to the MM of the current process.
68 *
69 * By using a %NULL value for the @pasid argument, this function can
70 * be used to simply validate that PASID support is available for the
71 * given device — i.e. that it is behind an IOMMU which has the
72 * requisite support, and is enabled.
73 *
74 * Page faults are handled transparently by the IOMMU code, and there
75 * should be no need for the device driver to be involved. If a page
76 * fault cannot be handled (i.e. is an invalid address rather than
77 * just needs paging in), then the page request will be completed by
78 * the core IOMMU code with appropriate status, and the device itself
79 * can then report the resulting fault to its driver via whatever
80 * mechanism is appropriate.
81 *
82 * Multiple calls from the same process may result in the same PASID
83 * being re-used. A reference count is kept.
84 */
85 extern int intel_svm_bind_mm(struct device *dev, int *pasid, int flags,
86 struct svm_dev_ops *ops);
87
88 /**
89 * intel_svm_unbind_mm() - Unbind a specified PASID
90 * @dev: Device for which PASID was allocated
91 * @pasid: PASID value to be unbound
92 *
93 * This function allows a PASID to be retired when the device no
94 * longer requires access to the address space of a given process.
95 *
96 * If the use count for the PASID in question reaches zero, the
97 * PASID is revoked and may no longer be used by hardware.
98 *
99 * Device drivers are required to ensure that no access (including
100 * page requests) is currently outstanding for the PASID in question,
101 * before calling this function.
102 */
103 extern int intel_svm_unbind_mm(struct device *dev, int pasid);
104
105 /**
106 * intel_svm_is_pasid_valid() - check if pasid is valid
107 * @dev: Device for which PASID was allocated
108 * @pasid: PASID value to be checked
109 *
110 * This function checks if the specified pasid is still valid. A
111 * valid pasid means the backing mm is still having a valid user.
112 * For kernel callers init_mm is always valid. for other mm, if mm->mm_users
113 * is non-zero, it is valid.
114 *
115 * returns -EINVAL if invalid pasid, 0 if pasid ref count is invalid
116 * 1 if pasid is valid.
117 */
118 extern int intel_svm_is_pasid_valid(struct device *dev, int pasid);
119
120 #else /* CONFIG_INTEL_IOMMU_SVM */
121
intel_svm_bind_mm(struct device * dev,int * pasid,int flags,struct svm_dev_ops * ops)122 static inline int intel_svm_bind_mm(struct device *dev, int *pasid,
123 int flags, struct svm_dev_ops *ops)
124 {
125 return -ENOSYS;
126 }
127
intel_svm_unbind_mm(struct device * dev,int pasid)128 static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
129 {
130 BUG();
131 }
132
intel_svm_is_pasid_valid(struct device * dev,int pasid)133 static inline int intel_svm_is_pasid_valid(struct device *dev, int pasid)
134 {
135 return -EINVAL;
136 }
137 #endif /* CONFIG_INTEL_IOMMU_SVM */
138
139 #define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL))
140
141 #endif /* __INTEL_SVM_H__ */
142