[PATCH v12 2/8] iommu/vt-d: Use a helper function to skip agaw for SL

Jacob Pan
2020-04-21T18:47:02Z

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>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
---
drivers/iommu/intel-pasid.c | 33 +++++++++++++++++++++++----------
1 file changed, 23 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index 22b30f10b396..d9cea3011b58 100644
--- 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);