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