iommu/vt-d: Use a helper function to skip agaw for SL

An Intel iommu domain uses 5-level page table by default. If the iommu
that the domain tries to attach supports less page levels, the top level
page tables should be skipped. Add a helper to do this so that it could
be used in other places.

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20200516062101.29541-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index 22b30f1..d9cea30 100644 (file)
--- a/drivers/iommu/intel-pasid.c
+++ b/drivers/iommu/intel-pasid.c
@@ -500,6 +500,25 @@ 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;
+       }
+
+       return agaw;
+}
+
+/*
  * Set up the scalable mode pasid entry for second only translation type.
  */
 int intel_pasid_setup_second_level(struct intel_iommu *iommu,
@@ -522,17 +541,11 @@ int intel_pasid_setup_second_level(struct intel_iommu *iommu,
                return -EINVAL;
        }
 
-       /*
-        * Skip top levels of page tables for iommu which has less agaw
-        * than default. Unnecessary for PT mode.
-        */
        pgd = domain->pgd;
-       for (agaw = domain->agaw; agaw > iommu->agaw; agaw--) {
-               pgd = phys_to_virt(dma_pte_addr(pgd));
-               if (!dma_pte_present(pgd)) {
-                       dev_err(dev, "Invalid domain page table\n");
-                       return -EINVAL;
-               }
+       agaw = iommu_skip_agaw(domain, iommu, &pgd);
+       if (agaw < 0) {
+               dev_err(dev, "Invalid domain page table\n");
+               return -EINVAL;
        }
 
        pgd_val = virt_to_phys(pgd);