From 2f26e0a9c9860db290d63e9d85c2c8c09813677f Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Wed, 9 Sep 2015 11:40:47 +0100 Subject: iommu/vt-d: Add basic SVM PASID support This provides basic PASID support for endpoint devices, tested with a version of the i915 driver. Signed-off-by: David Woodhouse --- include/linux/intel-svm.h | 82 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 include/linux/intel-svm.h (limited to 'include/linux/intel-svm.h') diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h new file mode 100644 index 000000000000..42f80ad7a7a0 --- /dev/null +++ b/include/linux/intel-svm.h @@ -0,0 +1,82 @@ +/* + * Copyright © 2015 Intel Corporation. + * + * Authors: David Woodhouse + * + * 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__ */ -- cgit v1.2.3-59-g8ed1b