include/linux/intel-svm.h

   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
 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
 128 static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
 129 {
 130         BUG();
 131 }
 132
 133 static 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__ */