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Commit 15060aba authored by CQ Tang's avatar CQ Tang Committed by Joerg Roedel
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iommu/vt-d: Helper function to query if a pasid has any active users 



A driver would need to know if there are any active references to a
a PASID before cleaning up its resources. This function helps check
if there are any active users of a PASID before it can perform any
recovery on that device.

To: Joerg Roedel <joro@8bytes.org>
To: linux-kernel@vger.kernel.org
To: David Woodhouse <dwmw2@infradead.org>
Cc: Jean-Phillipe Brucker <jean-philippe.brucker@arm.com>
Cc: iommu@lists.linux-foundation.org

Signed-off-by: default avatarCQ Tang <cq.tang@intel.com>
Signed-off-by: default avatarAshok Raj <ashok.raj@intel.com>
Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent 2ea659a9

drivers/iommu/intel-svm.c

+30 −0
Original line number Diff line number Diff line
@@ -489,6 +489,36 @@ int intel_svm_unbind_mm(struct device *dev, int pasid) 
}

EXPORT_SYMBOL_GPL(intel_svm_unbind_mm);



int intel_svm_is_pasid_valid(struct device *dev, int pasid)

{

	struct intel_iommu *iommu;

	struct intel_svm *svm;

	int ret = -EINVAL;



	mutex_lock(&pasid_mutex);

	iommu = intel_svm_device_to_iommu(dev);

	if (!iommu || !iommu->pasid_table)

		goto out;



	svm = idr_find(&iommu->pasid_idr, pasid);

	if (!svm)

		goto out;



	/* init_mm is used in this case */

	if (!svm->mm)

		ret = 1;

	else if (atomic_read(&svm->mm->mm_users) > 0)

		ret = 1;

	else

		ret = 0;



 out:

	mutex_unlock(&pasid_mutex);



	return ret;

}

EXPORT_SYMBOL_GPL(intel_svm_is_pasid_valid);



/* Page request queue descriptor */

struct page_req_dsc {

	u64 srr:1;

include/linux/intel-svm.h

+20 −0
Original line number Diff line number Diff line
@@ -102,6 +102,21 @@ extern int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, 
 */

extern int intel_svm_unbind_mm(struct device *dev, int pasid);



/**

 * intel_svm_is_pasid_valid() - check if pasid is valid

 * @dev:	Device for which PASID was allocated

 * @pasid:	PASID value to be checked

 *

 * This function checks if the specified pasid is still valid. A

 * valid pasid means the backing mm is still having a valid user.

 * For kernel callers init_mm is always valid. for other mm, if mm->mm_users

 * is non-zero, it is valid.

 *

 * returns -EINVAL if invalid pasid, 0 if pasid ref count is invalid

 * 1 if pasid is valid.

 */

extern int intel_svm_is_pasid_valid(struct device *dev, int pasid);



#else /* CONFIG_INTEL_IOMMU_SVM */



static inline int intel_svm_bind_mm(struct device *dev, int *pasid,
@@ -114,6 +129,11 @@ static inline int intel_svm_unbind_mm(struct device *dev, int pasid) 
{

	BUG();

}



static int intel_svm_is_pasid_valid(struct device *dev, int pasid)

{

	return -EINVAL;

}

#endif /* CONFIG_INTEL_IOMMU_SVM */



#define intel_svm_available(dev) (!intel_svm_bind_mm((dev), NULL, 0, NULL))