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