[PATCH V10 03/11] iommu/vt-d: Add a helper function to skip agaw

[Jacob Pan]

Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel-pasid.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index 22b30f10b396..191508c7c03e 100644
--- a/drivers/iommu/intel-pasid.c
+++ b/drivers/iommu/intel-pasid.c
@@ -500,6 +500,28 @@ int intel_pasid_setup_first_level(struct intel_iommu *iommu,
 }
 
 /*
+ * Skip top levels of page tables for iommu which has less agaw
+ * than default. Unnecessary for PT mode.
+ */
+static inline int iommu_skip_agaw(struct dmar_domain *domain,
+				  struct intel_iommu *iommu,
+				  struct dma_pte **pgd)
+{
+	int agaw;
+
+	for (agaw = domain->agaw; agaw > iommu->agaw; agaw--) {
+		*pgd = phys_to_virt(dma_pte_addr(*pgd));
+		if (!dma_pte_present(*pgd)) {
+			return -EINVAL;
+		}
+	}
+	pr_debug_ratelimited("%s: pgd: %llx, agaw %d d_agaw %d\n", __func__, (u64)*pgd,
+		iommu->agaw, domain->agaw);
+
+	return agaw;
+}
+
+/*
  * Set up the scalable mode pasid entry for second only translation type.
  */
 int intel_pasid_setup_second_level(struct intel_iommu *iommu,
-- 
2.7.4