Commit cb4789b0 authored by Jean-Philippe Brucker's avatar Jean-Philippe Brucker Committed by Will Deacon
Browse files

iommu/ioasid: Add ioasid references 



Let IOASID users take references to existing ioasids with ioasid_get().
ioasid_put() drops a reference and only frees the ioasid when its
reference number is zero. It returns true if the ioasid was freed.
For drivers that don't call ioasid_get(), ioasid_put() is the same as
ioasid_free().

Signed-off-by: default avatarJean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: default avatarEric Auger <eric.auger@redhat.com>
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20201106155048.997886-2-jean-philippe@linaro.org


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent f8394f23

drivers/iommu/intel/iommu.c

+2 −2
Original line number Diff line number Diff line
@@ -5198,7 +5198,7 @@ static void auxiliary_unlink_device(struct dmar_domain *domain, 
	domain->auxd_refcnt--;



	if (!domain->auxd_refcnt && domain->default_pasid > 0)

		ioasid_free(domain->default_pasid);

		ioasid_put(domain->default_pasid);

}



static int aux_domain_add_dev(struct dmar_domain *domain,
@@ -5259,7 +5259,7 @@ attach_failed: 
	spin_unlock(&iommu->lock);

	spin_unlock_irqrestore(&device_domain_lock, flags);

	if (!domain->auxd_refcnt && domain->default_pasid > 0)

		ioasid_free(domain->default_pasid);

		ioasid_put(domain->default_pasid);



	return ret;

}

drivers/iommu/intel/svm.c

+3 −3
Original line number Diff line number Diff line
@@ -598,7 +598,7 @@ intel_svm_bind_mm(struct device *dev, unsigned int flags, 
		if (mm) {

			ret = mmu_notifier_register(&svm->notifier, mm);

			if (ret) {

				ioasid_free(svm->pasid);

				ioasid_put(svm->pasid);

				kfree(svm);

				kfree(sdev);

				goto out;
@@ -616,7 +616,7 @@ intel_svm_bind_mm(struct device *dev, unsigned int flags, 
		if (ret) {

			if (mm)

				mmu_notifier_unregister(&svm->notifier, mm);

			ioasid_free(svm->pasid);

			ioasid_put(svm->pasid);

			kfree(svm);

			kfree(sdev);

			goto out;
@@ -689,7 +689,7 @@ static int intel_svm_unbind_mm(struct device *dev, u32 pasid) 
			kfree_rcu(sdev, rcu);



			if (list_empty(&svm->devs)) {

				ioasid_free(svm->pasid);

				ioasid_put(svm->pasid);

				if (svm->mm) {

					mmu_notifier_unregister(&svm->notifier, svm->mm);

					/* Clear mm's pasid. */

drivers/iommu/ioasid.c

+34 −4
Original line number Diff line number Diff line
@@ -2,7 +2,7 @@ 
/*

 * I/O Address Space ID allocator. There is one global IOASID space, split into

 * subsets. Users create a subset with DECLARE_IOASID_SET, then allocate and

 * free IOASIDs with ioasid_alloc and ioasid_free.

 * free IOASIDs with ioasid_alloc and ioasid_put.

 */

#include <linux/ioasid.h>

#include <linux/module.h>
@@ -15,6 +15,7 @@ struct ioasid_data { 
	struct ioasid_set *set;

	void *private;

	struct rcu_head rcu;

	refcount_t refs;

};



/*
@@ -314,6 +315,7 @@ ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max, 


	data->set = set;

	data->private = private;

	refcount_set(&data->refs, 1);



	/*

	 * Custom allocator needs allocator data to perform platform specific
@@ -346,11 +348,34 @@ exit_free: 
EXPORT_SYMBOL_GPL(ioasid_alloc);



/**

 * ioasid_free - Free an IOASID

 * ioasid_get - obtain a reference to the IOASID

 */

void ioasid_get(ioasid_t ioasid)

{

	struct ioasid_data *ioasid_data;



	spin_lock(&ioasid_allocator_lock);

	ioasid_data = xa_load(&active_allocator->xa, ioasid);

	if (ioasid_data)

		refcount_inc(&ioasid_data->refs);

	else

		WARN_ON(1);

	spin_unlock(&ioasid_allocator_lock);

}

EXPORT_SYMBOL_GPL(ioasid_get);



/**

 * ioasid_put - Release a reference to an ioasid

 * @ioasid: the ID to remove

 *

 * Put a reference to the IOASID, free it when the number of references drops to

 * zero.

 *

 * Return: %true if the IOASID was freed, %false otherwise.

 */

void ioasid_free(ioasid_t ioasid)

bool ioasid_put(ioasid_t ioasid)

{

	bool free = false;

	struct ioasid_data *ioasid_data;



	spin_lock(&ioasid_allocator_lock);
@@ -360,6 +385,10 @@ void ioasid_free(ioasid_t ioasid) 
		goto exit_unlock;

	}



	free = refcount_dec_and_test(&ioasid_data->refs);

	if (!free)

		goto exit_unlock;



	active_allocator->ops->free(ioasid, active_allocator->ops->pdata);

	/* Custom allocator needs additional steps to free the xa element */

	if (active_allocator->flags & IOASID_ALLOCATOR_CUSTOM) {
@@ -369,8 +398,9 @@ void ioasid_free(ioasid_t ioasid) 


exit_unlock:

	spin_unlock(&ioasid_allocator_lock);

	return free;

}

EXPORT_SYMBOL_GPL(ioasid_free);

EXPORT_SYMBOL_GPL(ioasid_put);



/**

 * ioasid_find - Find IOASID data

include/linux/ioasid.h

+8 −2
Original line number Diff line number Diff line
@@ -34,7 +34,8 @@ struct ioasid_allocator_ops { 
#if IS_ENABLED(CONFIG_IOASID)

ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, ioasid_t max,

		      void *private);

void ioasid_free(ioasid_t ioasid);

void ioasid_get(ioasid_t ioasid);

bool ioasid_put(ioasid_t ioasid);

void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,

		  bool (*getter)(void *));

int ioasid_register_allocator(struct ioasid_allocator_ops *allocator);
@@ -48,10 +49,15 @@ static inline ioasid_t ioasid_alloc(struct ioasid_set *set, ioasid_t min, 
	return INVALID_IOASID;

}



static inline void ioasid_free(ioasid_t ioasid)

static inline void ioasid_get(ioasid_t ioasid)

{

}



static inline bool ioasid_put(ioasid_t ioasid)

{

	return false;

}



static inline void *ioasid_find(struct ioasid_set *set, ioasid_t ioasid,

				bool (*getter)(void *))

{

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