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iommu/vt-d: Helper function to query if a pasid has any active users

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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: CQ Tang <cq.tang@intel.com>
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
CQ Tang 2017-05-10 11:39:03 -07:00 committed by Joerg Roedel
parent 2ea659a9ef
commit 15060aba71
2 changed files with 50 additions and 0 deletions
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30
drivers/iommu/intel-svm.c
View File

@ -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;

20
include/linux/intel-svm.h
View File

@ -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))