[PATCH v4 2/6] iommu: Add a helper to do PASID lookup from domain

[Jacob Pan <jacob.jun.pan@linux.intel.com>]

IOMMU group maintains a PASID array which stores the associated IOMMU
domains. This patch introduces a helper function to do domain to PASID
look up. It will be used by TLB flush and device-PASID attach verification.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 drivers/iommu/iommu.c | 22 ++++++++++++++++++++++
 include/linux/iommu.h |  6 +++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 00d0262a1fe9..22f44833db64 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3199,3 +3199,25 @@ struct iommu_domain *iommu_get_domain_for_iopf(struct device *dev,
 
 	return domain;
 }
+
+ioasid_t iommu_get_pasid_from_domain(struct device *dev, struct iommu_domain *domain)
+{
+	struct iommu_domain *tdomain;
+	struct iommu_group *group;
+	unsigned long index;
+	ioasid_t pasid = INVALID_IOASID;
+
+	group = iommu_group_get(dev);
+	if (!group)
+		return pasid;
+
+	xa_for_each(&group->pasid_array, index, tdomain) {
+		if (domain == tdomain) {
+			pasid = index;
+			break;
+		}
+	}
+	iommu_group_put(group);
+
+	return pasid;
+}
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 36ad007084cc..c0440a4be699 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -694,7 +694,7 @@ void iommu_detach_device_pasid(struct iommu_domain *domain,
 			       struct device *dev, ioasid_t pasid);
 struct iommu_domain *
 iommu_get_domain_for_iopf(struct device *dev, ioasid_t pasid);
-
+ioasid_t iommu_get_pasid_from_domain(struct device *dev, struct iommu_domain *domain);
 #else /* CONFIG_IOMMU_API */
 
 struct iommu_ops {};
@@ -1070,6 +1070,10 @@ iommu_get_domain_for_iopf(struct device *dev, ioasid_t pasid)
 {
 	return NULL;
 }
+static ioasid_t iommu_get_pasid_from_domain(struct device *dev, struct iommu_domain *domain)
+{
+	return INVALID_IOASID;
+}
 #endif /* CONFIG_IOMMU_API */
 
 #ifdef CONFIG_IOMMU_SVA
-- 
2.25.1