LXR linux/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
  19struct device;
  20
  21struct 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 */
  85extern 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 */
 103extern int intel_svm_unbind_mm(struct device *dev, int pasid);
 104
 105#else /* CONFIG_INTEL_IOMMU_SVM */
 106
 107static inline int intel_svm_bind_mm(struct device *dev, int *pasid,
 108                                    int flags, struct svm_dev_ops *ops)
 109{
 110        return -ENOSYS;
 111}
 112
 113static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
 114{
 115        BUG();
 116}
 117#endif /* CONFIG_INTEL_IOMMU_SVM */
 118
 119#define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL))
 120
 121#endif /* __INTEL_SVM_H__ */
 122