1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Copyright © 2015 Intel Corporation.
4 *
5 * Authors: David Woodhouse <David.Woodhouse@intel.com>
6 */
7
8 #ifndef __INTEL_SVM_H__
9 #define __INTEL_SVM_H__
10
11 struct device;
12
13 struct svm_dev_ops {
14 void (*fault_cb)(struct device *dev, int pasid, u64 address,
15 void *private, int rwxp, int response);
16 };
17
18 /* Values for rxwp in fault_cb callback */
19 #define SVM_REQ_READ (1<<3)
20 #define SVM_REQ_WRITE (1<<2)
21 #define SVM_REQ_EXEC (1<<1)
22 #define SVM_REQ_PRIV (1<<0)
23
24
25 /*
26 * The SVM_FLAG_PRIVATE_PASID flag requests a PASID which is *not* the "main"
27 * PASID for the current process. Even if a PASID already exists, a new one
28 * will be allocated. And the PASID allocated with SVM_FLAG_PRIVATE_PASID
29 * will not be given to subsequent callers. This facility allows a driver to
30 * disambiguate between multiple device contexts which access the same MM,
31 * if there is no other way to do so. It should be used sparingly, if at all.
32 */
33 #define SVM_FLAG_PRIVATE_PASID (1<<0)
34
35 /*
36 * The SVM_FLAG_SUPERVISOR_MODE flag requests a PASID which can be used only
37 * for access to kernel addresses. No IOTLB flushes are automatically done
38 * for kernel mappings; it is valid only for access to the kernel's static
39 * 1:1 mapping of physical memory — not to vmalloc or even module mappings.
40 * A future API addition may permit the use of such ranges, by means of an
41 * explicit IOTLB flush call (akin to the DMA API's unmap method).
42 *
43 * It is unlikely that we will ever hook into flush_tlb_kernel_range() to
44 * do such IOTLB flushes automatically.
45 */
46 #define SVM_FLAG_SUPERVISOR_MODE (1<<1)
47
48 #ifdef CONFIG_INTEL_IOMMU_SVM
49
50 /**
51 * intel_svm_bind_mm() - Bind the current process to a PASID
52 * @dev: Device to be granted access
53 * @pasid: Address for allocated PASID
54 * @flags: Flags. Later for requesting supervisor mode, etc.
55 * @ops: Callbacks to device driver
56 *
57 * This function attempts to enable PASID support for the given device.
58 * If the @pasid argument is non-%NULL, a PASID is allocated for access
59 * to the MM of the current process.
60 *
61 * By using a %NULL value for the @pasid argument, this function can
62 * be used to simply validate that PASID support is available for the
63 * given device — i.e. that it is behind an IOMMU which has the
64 * requisite support, and is enabled.
65 *
66 * Page faults are handled transparently by the IOMMU code, and there
67 * should be no need for the device driver to be involved. If a page
68 * fault cannot be handled (i.e. is an invalid address rather than
69 * just needs paging in), then the page request will be completed by
70 * the core IOMMU code with appropriate status, and the device itself
71 * can then report the resulting fault to its driver via whatever
72 * mechanism is appropriate.
73 *
74 * Multiple calls from the same process may result in the same PASID
75 * being re-used. A reference count is kept.
76 */
77 extern int intel_svm_bind_mm(struct device *dev, int *pasid, int flags,
78 struct svm_dev_ops *ops);
79
80 /**
81 * intel_svm_unbind_mm() - Unbind a specified PASID
82 * @dev: Device for which PASID was allocated
83 * @pasid: PASID value to be unbound
84 *
85 * This function allows a PASID to be retired when the device no
86 * longer requires access to the address space of a given process.
87 *
88 * If the use count for the PASID in question reaches zero, the
89 * PASID is revoked and may no longer be used by hardware.
90 *
91 * Device drivers are required to ensure that no access (including
92 * page requests) is currently outstanding for the PASID in question,
93 * before calling this function.
94 */
95 extern int intel_svm_unbind_mm(struct device *dev, int pasid);
96
97 /**
98 * intel_svm_is_pasid_valid() - check if pasid is valid
99 * @dev: Device for which PASID was allocated
100 * @pasid: PASID value to be checked
101 *
102 * This function checks if the specified pasid is still valid. A
103 * valid pasid means the backing mm is still having a valid user.
104 * For kernel callers init_mm is always valid. for other mm, if mm->mm_users
105 * is non-zero, it is valid.
106 *
107 * returns -EINVAL if invalid pasid, 0 if pasid ref count is invalid
108 * 1 if pasid is valid.
109 */
110 extern int intel_svm_is_pasid_valid(struct device *dev, int pasid);
111
112 #else /* CONFIG_INTEL_IOMMU_SVM */
113
114 static inline int intel_svm_bind_mm(struct device *dev, int *pasid,
115 int flags, struct svm_dev_ops *ops)
116 {
117 return -ENOSYS;
118 }
119
120 static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
121 {
122 BUG();
123 }
124
125 static inline int intel_svm_is_pasid_valid(struct device *dev, int pasid)
126 {
127 return -EINVAL;
128 }
129 #endif /* CONFIG_INTEL_IOMMU_SVM */
130
131 #define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL))
132
133 #endif /* __INTEL_SVM_H__ */