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Subject[PATCH v11 03/10] iommu/vt-d: Use a helper function to skip agaw for SL
Date
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.

---
v11 Added Baolu's commit message and squashed 4 & 5 from v10.
---

Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
drivers/iommu/intel-pasid.c | 34 ++++++++++++++++++++++++----------
1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
index 22b30f10b396..66c364719ad1 100644
--- a/drivers/iommu/intel-pasid.c
+++ b/drivers/iommu/intel-pasid.c
@@ -500,6 +500,26 @@ 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 +542,11 @@ 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);
--
2.7.4
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