Commit 2dcebc7d authored by Jacob Pan's avatar Jacob Pan Committed by Joerg Roedel
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iommu: Move global PASID allocation from SVA to core 



Intel ENQCMD requires a single PASID to be shared between multiple
devices, as the PASID is stored in a single MSR register per-process
and userspace can use only that one PASID.

This means that the PASID allocation for any ENQCMD using device driver
must always come from a shared global pool, regardless of what kind of
domain the PASID will be used with.

Split the code for the global PASID allocator into
iommu_alloc/free_global_pasid() so that drivers can attach non-SVA
domains to PASIDs as well.

This patch moves global PASID allocation APIs from SVA to IOMMU APIs.
Reserved PASIDs, currently only RID_PASID, are excluded from the global
PASID allocation.

It is expected that device drivers will use the allocated PASIDs to
attach to appropriate IOMMU domains for use.

Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarJacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20230802212427.1497170-3-jacob.jun.pan@linux.intel.com


Signed-off-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 42987801

drivers/iommu/iommu-sva.c

+10 −19
Original line number Diff line number Diff line
@@ -10,34 +10,30 @@ 
#include "iommu-sva.h"



static DEFINE_MUTEX(iommu_sva_lock);

static DEFINE_IDA(iommu_global_pasid_ida);



/* Allocate a PASID for the mm within range (inclusive) */

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

static int iommu_sva_alloc_pasid(struct mm_struct *mm, struct device *dev)

{

	ioasid_t pasid;

	int ret = 0;



	if (min == IOMMU_PASID_INVALID ||

	    max == IOMMU_PASID_INVALID ||

	    min == 0 || max < min)

		return -EINVAL;



	if (!arch_pgtable_dma_compat(mm))

		return -EBUSY;



	mutex_lock(&iommu_sva_lock);

	/* Is a PASID already associated with this mm? */

	if (mm_valid_pasid(mm)) {

		if (mm->pasid < min || mm->pasid > max)

		if (mm->pasid >= dev->iommu->max_pasids)

			ret = -EOVERFLOW;

		goto out;

	}



	ret = ida_alloc_range(&iommu_global_pasid_ida, min, max, GFP_KERNEL);

	if (ret < 0)

	pasid = iommu_alloc_global_pasid(dev);

	if (pasid == IOMMU_PASID_INVALID) {

		ret = -ENOSPC;

		goto out;



	mm->pasid = ret;

	}

	mm->pasid = pasid;

	ret = 0;

out:

	mutex_unlock(&iommu_sva_lock);
@@ -64,15 +60,10 @@ struct iommu_sva *iommu_sva_bind_device(struct device *dev, struct mm_struct *mm 
{

	struct iommu_domain *domain;

	struct iommu_sva *handle;

	ioasid_t max_pasids;

	int ret;



	max_pasids = dev->iommu->max_pasids;

	if (!max_pasids)

		return ERR_PTR(-EOPNOTSUPP);



	/* Allocate mm->pasid if necessary. */

	ret = iommu_sva_alloc_pasid(mm, 1, max_pasids - 1);

	ret = iommu_sva_alloc_pasid(mm, dev);

	if (ret)

		return ERR_PTR(ret);
@@ -217,5 +208,5 @@ void mm_pasid_drop(struct mm_struct *mm) 
	if (likely(!mm_valid_pasid(mm)))

		return;



	ida_free(&iommu_global_pasid_ida, mm->pasid);

	iommu_free_global_pasid(mm->pasid);

}

drivers/iommu/iommu.c

+28 −0
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ 


static struct kset *iommu_group_kset;

static DEFINE_IDA(iommu_group_ida);

static DEFINE_IDA(iommu_global_pasid_ida);



static unsigned int iommu_def_domain_type __read_mostly;

static bool iommu_dma_strict __read_mostly = IS_ENABLED(CONFIG_IOMMU_DEFAULT_DMA_STRICT);
@@ -3400,3 +3401,30 @@ struct iommu_domain *iommu_sva_domain_alloc(struct device *dev, 


	return domain;

}



ioasid_t iommu_alloc_global_pasid(struct device *dev)

{

	int ret;



	/* max_pasids == 0 means that the device does not support PASID */

	if (!dev->iommu->max_pasids)

		return IOMMU_PASID_INVALID;



	/*

	 * max_pasids is set up by vendor driver based on number of PASID bits

	 * supported but the IDA allocation is inclusive.

	 */

	ret = ida_alloc_range(&iommu_global_pasid_ida, IOMMU_FIRST_GLOBAL_PASID,

			      dev->iommu->max_pasids - 1, GFP_KERNEL);

	return ret < 0 ? IOMMU_PASID_INVALID : ret;

}

EXPORT_SYMBOL_GPL(iommu_alloc_global_pasid);



void iommu_free_global_pasid(ioasid_t pasid)

{

	if (WARN_ON(pasid == IOMMU_PASID_INVALID))

		return;



	ida_free(&iommu_global_pasid_ida, pasid);

}

EXPORT_SYMBOL_GPL(iommu_free_global_pasid);

include/linux/iommu.h

+10 −0
Original line number Diff line number Diff line
@@ -197,6 +197,7 @@ enum iommu_dev_features { 
};



#define IOMMU_NO_PASID	(0U) /* Reserved for DMA w/o PASID */

#define IOMMU_FIRST_GLOBAL_PASID	(1U) /*starting range for allocation */

#define IOMMU_PASID_INVALID	(-1U)

typedef unsigned int ioasid_t;
@@ -728,6 +729,8 @@ void iommu_detach_device_pasid(struct iommu_domain *domain, 
struct iommu_domain *

iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid,

			       unsigned int type);

ioasid_t iommu_alloc_global_pasid(struct device *dev);

void iommu_free_global_pasid(ioasid_t pasid);

#else /* CONFIG_IOMMU_API */



struct iommu_ops {};
@@ -1089,6 +1092,13 @@ iommu_get_domain_for_dev_pasid(struct device *dev, ioasid_t pasid, 
{

	return NULL;

}



static inline ioasid_t iommu_alloc_global_pasid(struct device *dev)

{

	return IOMMU_PASID_INVALID;

}



static inline void iommu_free_global_pasid(ioasid_t pasid) {}

#endif /* CONFIG_IOMMU_API */



/**