LXR linux/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
  11struct device;
  12
  13struct 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 */
  77extern 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 */
  95extern 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 */
 110extern int intel_svm_is_pasid_valid(struct device *dev, int pasid);
 111
 112#else /* CONFIG_INTEL_IOMMU_SVM */
 113
 114static 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
 120static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
 121{
 122        BUG();
 123}
 124
 125static 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__ */
 134