linux-kernel - [PATCH v5 6/9] iommu/vt-d: Make first level IOVA canonical

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Date:   Tue, 24 Dec 2019 15:44:59 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>,
        Alex Williamson <alex.williamson@...hat.com>
Cc:     ashok.raj@...el.com, sanjay.k.kumar@...el.com,
        jacob.jun.pan@...ux.intel.com, kevin.tian@...el.com,
        yi.l.liu@...el.com, yi.y.sun@...el.com,
        Peter Xu <peterx@...hat.com>, iommu@...ts.linux-foundation.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH v5 6/9] iommu/vt-d: Make first level IOVA canonical

First-level translation restricts the input-address to a canonical
address (i.e., address bits 63:N have the same value as address
bit [N-1], where N is 48-bits with 4-level paging and 57-bits with
5-level paging). (section 3.6 in the spec)

This makes first level IOVA canonical by using IOVA with bit [N-1]
always cleared.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel-iommu.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 54db6bc0b281..1ebf5ed460cf 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3505,8 +3505,21 @@ static unsigned long intel_alloc_iova(struct device *dev,
 {
 	unsigned long iova_pfn;
 
-	/* Restrict dma_mask to the width that the iommu can handle */
-	dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw), dma_mask);
+	/*
+	 * Restrict dma_mask to the width that the iommu can handle.
+	 * First-level translation restricts the input-address to a
+	 * canonical address (i.e., address bits 63:N have the same
+	 * value as address bit [N-1], where N is 48-bits with 4-level
+	 * paging and 57-bits with 5-level paging). Hence, skip bit
+	 * [N-1].
+	 */
+	if (domain_use_first_level(domain))
+		dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw - 1),
+				 dma_mask);
+	else
+		dma_mask = min_t(uint64_t, DOMAIN_MAX_ADDR(domain->gaw),
+				 dma_mask);
+
 	/* Ensure we reserve the whole size-aligned region */
 	nrpages = __roundup_pow_of_two(nrpages);
 
-- 
2.17.1