include/linux/intel-svm.h

   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 acccess
  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 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__ */