linux-kernel - [PATCH v2] iommu/vt-d: Fix a bug in intel_iommu_iova_to

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Message-Id: <20200220194431.169629-1-yonghyun@google.com>
Date:   Thu, 20 Feb 2020 11:44:31 -0800
From:   Yonghyun Hwang <yonghyun@...gle.com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>
Cc:     iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Havard Skinnemoen <hskinnemoen@...gle.com>,
        Deepa Dinamani <deepadinamani@...gle.com>,
        Moritz Fischer <mdf@...nel.org>,
        Yonghyun Hwang <yonghyun@...gle.com>
Subject: [PATCH v2] iommu/vt-d: Fix a bug in intel_iommu_iova_to_phys() for
 huge page

intel_iommu_iova_to_phys() has a bug when it translates an IOVA for a huge
page onto its corresponding physical address. This commit fixes the bug by
accomodating the level of page entry for the IOVA and adds IOVA's lower
address to the physical address.

Signed-off-by: Yonghyun Hwang <yonghyun@...gle.com>
---

Changes from v1:
- level cannot be 0. So, the condition, "if (level > 1)", is removed, which results in a simple code.
- a macro, BIT_MASK, is used to have a bit mask

---
 drivers/iommu/intel-iommu.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 932267f49f9a..4fd5c6287b6d 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -5554,7 +5554,9 @@ static phys_addr_t intel_iommu_iova_to_phys(struct iommu_domain *domain,
 
 	pte = pfn_to_dma_pte(dmar_domain, iova >> VTD_PAGE_SHIFT, &level);
 	if (pte)
-		phys = dma_pte_addr(pte);
+		phys = dma_pte_addr(pte) +
+			(iova & (BIT_MASK(level_to_offset_bits(level) +
+						VTD_PAGE_SHIFT) - 1));
 
 	return phys;
 }
-- 
2.25.0.265.gbab2e86ba0-goog