87 lines
2.2 KiB
C
87 lines
2.2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Helpers for IOMMU drivers implementing SVA
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*/
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#include <linux/mutex.h>
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#include <linux/sched/mm.h>
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#include "iommu-sva-lib.h"
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static DEFINE_MUTEX(iommu_sva_lock);
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static DECLARE_IOASID_SET(iommu_sva_pasid);
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/**
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* iommu_sva_alloc_pasid - Allocate a PASID for the mm
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* @mm: the mm
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* @min: minimum PASID value (inclusive)
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* @max: maximum PASID value (inclusive)
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*
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* Try to allocate a PASID for this mm, or take a reference to the existing one
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* provided it fits within the [@min, @max] range. On success the PASID is
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* available in mm->pasid, and must be released with iommu_sva_free_pasid().
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* @min must be greater than 0, because 0 indicates an unused mm->pasid.
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*
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* Returns 0 on success and < 0 on error.
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*/
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int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max)
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{
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int ret = 0;
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ioasid_t pasid;
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if (min == INVALID_IOASID || max == INVALID_IOASID ||
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min == 0 || max < min)
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return -EINVAL;
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mutex_lock(&iommu_sva_lock);
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if (mm->pasid) {
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if (mm->pasid >= min && mm->pasid <= max)
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ioasid_get(mm->pasid);
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else
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ret = -EOVERFLOW;
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} else {
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pasid = ioasid_alloc(&iommu_sva_pasid, min, max, mm);
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if (pasid == INVALID_IOASID)
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ret = -ENOMEM;
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else
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mm->pasid = pasid;
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}
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mutex_unlock(&iommu_sva_lock);
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return ret;
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}
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EXPORT_SYMBOL_GPL(iommu_sva_alloc_pasid);
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/**
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* iommu_sva_free_pasid - Release the mm's PASID
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* @mm: the mm
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*
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* Drop one reference to a PASID allocated with iommu_sva_alloc_pasid()
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*/
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void iommu_sva_free_pasid(struct mm_struct *mm)
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{
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mutex_lock(&iommu_sva_lock);
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if (ioasid_put(mm->pasid))
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mm->pasid = 0;
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mutex_unlock(&iommu_sva_lock);
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}
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EXPORT_SYMBOL_GPL(iommu_sva_free_pasid);
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/* ioasid_find getter() requires a void * argument */
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static bool __mmget_not_zero(void *mm)
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{
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return mmget_not_zero(mm);
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}
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/**
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* iommu_sva_find() - Find mm associated to the given PASID
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* @pasid: Process Address Space ID assigned to the mm
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*
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* On success a reference to the mm is taken, and must be released with mmput().
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*
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* Returns the mm corresponding to this PASID, or an error if not found.
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*/
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struct mm_struct *iommu_sva_find(ioasid_t pasid)
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{
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return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
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}
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EXPORT_SYMBOL_GPL(iommu_sva_find);
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