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