linux-kernel - [PATCH] iommu/dma: Fix IOVA reserve dma ranges

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Date:   Wed,  9 Sep 2020 11:02:34 +0530
From:   Srinath Mannam <srinath.mannam@...adcom.com>
To:     Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>, poza@...eaurora.org
Cc:     bcm-kernel-feedback-list@...adcom.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Srinath Mannam <srinath.mannam@...adcom.com>
Subject: [PATCH] iommu/dma: Fix IOVA reserve dma ranges

Fix IOVA reserve failure for memory regions listed in dma-ranges in the
following cases.

- start address of memory region is 0x0.
- end address of a memory region is equal to start address of next memory
  region.

Fixes: aadad097cd46f ("iommu/dma: Reserve IOVA for PCIe inaccessible DMA address")
Signed-off-by: Srinath Mannam <srinath.mannam@...adcom.com>
---
 drivers/iommu/dma-iommu.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 5141d49a046b..0a3f67a4f9ae 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -213,14 +213,21 @@ static int iova_reserve_pci_windows(struct pci_dev *dev,
 	resource_list_for_each_entry(window, &bridge->dma_ranges) {
 		end = window->res->start - window->offset;
 resv_iova:
+		if (end < start) {
+			/* dma_ranges list should be sorted */
+			dev_err(&dev->dev, "Failed to reserve IOVA\n");
+			return -EINVAL;
+		}
+		/*
+		 * Skip the cases when start address of first memory region is
+		 * 0x0 and end address of one memory region and start address
+		 * of next memory region are equal. Reserve IOVA for rest of
+		 * addresses fall in between given memory ranges.
+		 */
 		if (end > start) {
 			lo = iova_pfn(iovad, start);
 			hi = iova_pfn(iovad, end);
 			reserve_iova(iovad, lo, hi);
-		} else {
-			/* dma_ranges list should be sorted */
-			dev_err(&dev->dev, "Failed to reserve IOVA\n");
-			return -EINVAL;
 		}
 
 		start = window->res->end - window->offset + 1;
-- 
2.17.1