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

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Date:   Fri, 20 Mar 2020 16:27:33 -0700
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     "Lu Baolu" <baolu.lu@...ux.intel.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>
Cc:     "Yi Liu" <yi.l.liu@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        "Christoph Hellwig" <hch@...radead.org>,
        Jonathan Cameron <jic23@...nel.org>,
        Eric Auger <eric.auger@...hat.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH V10 03/11] iommu/vt-d: Add a helper function to skip agaw

Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
---
 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