83 lines
2.8 KiB
C
83 lines
2.8 KiB
C
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/*
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* Copyright © 2015 Intel Corporation.
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*
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* Authors: David Woodhouse <David.Woodhouse@intel.com>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*/
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#ifndef __INTEL_SVM_H__
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#define __INTEL_SVM_H__
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#ifdef CONFIG_INTEL_IOMMU_SVM
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struct device;
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/**
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* intel_svm_bind_mm() - Bind the current process to a PASID
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* @dev: Device to be granted acccess
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* @pasid: Address for allocated PASID
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*
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* This function attempts to enable PASID support for the given device.
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* If the @pasid argument is non-%NULL, a PASID is allocated for access
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* to the MM of the current process.
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*
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* By using a %NULL value for the @pasid argument, this function can
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* be used to simply validate that PASID support is available for the
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* given device — i.e. that it is behind an IOMMU which has the
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* requisite support, and is enabled.
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*
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* Page faults are handled transparently by the IOMMU code, and there
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* should be no need for the device driver to be involved. If a page
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* fault cannot be handled (i.e. is an invalid address rather than
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* just needs paging in), then the page request will be completed by
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* the core IOMMU code with appropriate status, and the device itself
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* can then report the resulting fault to its driver via whatever
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* mechanism is appropriate.
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*
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* Multiple calls from the same process may result in the same PASID
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* being re-used. A reference count is kept.
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*/
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extern int intel_svm_bind_mm(struct device *dev, int *pasid);
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/**
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* intel_svm_unbind_mm() - Unbind a specified PASID
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* @dev: Device for which PASID was allocated
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* @pasid: PASID value to be unbound
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*
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* This function allows a PASID to be retired when the device no
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* longer requires access to the address space of a given process.
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*
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* If the use count for the PASID in question reaches zero, the
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* PASID is revoked and may no longer be used by hardware.
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*
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* Device drivers are required to ensure that no access (including
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* page requests) is currently outstanding for the PASID in question,
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* before calling this function.
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*/
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extern int intel_svm_unbind_mm(struct device *dev, int pasid);
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#else /* CONFIG_INTEL_IOMMU_SVM */
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static inline int intel_svm_bind_mm(struct device *dev, int *pasid)
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{
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return -ENOSYS;
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}
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static inline int intel_svm_unbind_mm(struct device *dev, int pasid)
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{
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BUG();
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}
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#endif /* CONFIG_INTEL_IOMMU_SVM */
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#define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL))
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#endif /* __INTEL_SVM_H__ */
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