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authorDavid Woodhouse <David.Woodhouse@intel.com>2015-09-09 11:40:47 +0100
committerDavid Woodhouse <David.Woodhouse@intel.com>2015-10-15 12:55:45 +0100
commit2f26e0a9c9860db290d63e9d85c2c8c09813677f (patch)
tree6a3712f991b9ae60b8eaece608c355b66fd3e5b5 /include/linux/intel-svm.h
parentb16d0cb9e2fc5c311948c660dd6f4b59a9ccd333 (diff)
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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 <David.Woodhouse@intel.com>
Diffstat (limited to 'include/linux/intel-svm.h')
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diff --git a/include/linux/intel-svm.h b/include/linux/intel-svm.h
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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__ */