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 #ifdef CONFIG_INTEL_IOMMU_SVM
  20
  21 struct device;
  22
  23 struct svm_dev_ops {
  24         void (*fault_cb)(struct device *dev, int pasid, u64 address,
  25                          u32 private, int rwxp, int response);
  26 };
  27
  28 /* Values for rxwp in fault_cb callback */
  29 #define SVM_REQ_READ    (1<<3)
  30 #define SVM_REQ_WRITE   (1<<2)
  31 #define SVM_REQ_EXEC    (1<<1)
  32 #define SVM_REQ_PRIV    (1<<0)
  33
  34 /**
  35  * intel_svm_bind_mm() - Bind the current process to a PASID
  36  * @dev:        Device to be granted acccess
  37  * @pasid:      Address for allocated PASID
  38  * @flags:      Flags. Later for requesting supervisor mode, etc.
  39  * @ops:        Callbacks to device driver
  40  *
  41  * This function attempts to enable PASID support for the given device.
  42  * If the @pasid argument is non-%NULL, a PASID is allocated for access
  43  * to the MM of the current process.
  44  *
  45  * By using a %NULL value for the @pasid argument, this function can
  46  * be used to simply validate that PASID support is available for the
  47  * given device — i.e. that it is behind an IOMMU which has the
  48  * requisite support, and is enabled.
  49  *
  50  * Page faults are handled transparently by the IOMMU code, and there
  51  * should be no need for the device driver to be involved. If a page
  52  * fault cannot be handled (i.e. is an invalid address rather than
  53  * just needs paging in), then the page request will be completed by
  54  * the core IOMMU code with appropriate status, and the device itself
  55  * can then report the resulting fault to its driver via whatever
  56  * mechanism is appropriate.
  57  *
  58  * Multiple calls from the same process may result in the same PASID
  59  * being re-used. A reference count is kept.
  60  */
  61 extern int intel_svm_bind_mm(struct device *dev, int *pasid, int flags,
  62                              struct svm_dev_ops *ops);
  63
  64 /**
  65  * intel_svm_unbind_mm() - Unbind a specified PASID
  66  * @dev:        Device for which PASID was allocated
  67  * @pasid:      PASID value to be unbound
  68  *
  69  * This function allows a PASID to be retired when the device no
  70  * longer requires access to the address space of a given process.
  71  *
  72  * If the use count for the PASID in question reaches zero, the
  73  * PASID is revoked and may no longer be used by hardware.
  74  *
  75  * Device drivers are required to ensure that no access (including
  76  * page requests) is currently outstanding for the PASID in question,
  77  * before calling this function.
  78  */
  79 extern int intel_svm_unbind_mm(struct device *dev, int pasid);
  80
  81 #else /* CONFIG_INTEL_IOMMU_SVM */
  82
  83 static inline int intel_svm_bind_mm(struct device *dev, int *pasid,
  84                                     int flags, struct svm_dev_ops *ops)
  85 {
  86         return -ENOSYS;
  87 }
  88
  89 static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
  90 {
  91         BUG();
  92 }
  93 #endif /* CONFIG_INTEL_IOMMU_SVM */
  94
  95 #define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL))
  96
  97 #endif /* __INTEL_SVM_H__ */