Commit cfc78dfd authored by Jean-Philippe Brucker's avatar Jean-Philippe Brucker Committed by Will Deacon
Browse files

iommu/sva: Add PASID helpers 



Let IOMMU drivers allocate a single PASID per mm. Store the mm in the
IOASID set to allow refcounting and searching mm by PASID, when handling
an I/O page fault.

Signed-off-by: default avatarJean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20201106155048.997886-3-jean-philippe@linaro.org


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent cb4789b0

drivers/iommu/Kconfig

+5 −0
Original line number Diff line number Diff line
@@ -103,6 +103,11 @@ config IOMMU_DMA 
	select IRQ_MSI_IOMMU

	select NEED_SG_DMA_LENGTH



# Shared Virtual Addressing library

config IOMMU_SVA_LIB

	bool

	select IOASID



config FSL_PAMU

	bool "Freescale IOMMU support"

	depends on PCI

drivers/iommu/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -27,3 +27,4 @@ obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o 
obj-$(CONFIG_S390_IOMMU) += s390-iommu.o

obj-$(CONFIG_HYPERV_IOMMU) += hyperv-iommu.o

obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o

obj-$(CONFIG_IOMMU_SVA_LIB) += iommu-sva-lib.o

drivers/iommu/iommu-sva-lib.c

0 → 100644
+86 −0
Original line number Diff line number Diff line 
// 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);

drivers/iommu/iommu-sva-lib.h

0 → 100644
+15 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */

/*

 * SVA library for IOMMU drivers

 */

#ifndef _IOMMU_SVA_LIB_H

#define _IOMMU_SVA_LIB_H



#include <linux/ioasid.h>

#include <linux/mm_types.h>



int iommu_sva_alloc_pasid(struct mm_struct *mm, ioasid_t min, ioasid_t max);

void iommu_sva_free_pasid(struct mm_struct *mm);

struct mm_struct *iommu_sva_find(ioasid_t pasid);



#endif /* _IOMMU_SVA_LIB_H */