linux-kernel - [PATCH v6 2/3] iommu/dma: Reserve IOVA for PCIe inaccessible DMA address

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Date:   Fri,  3 May 2019 19:35:33 +0530
From:   Srinath Mannam <srinath.mannam@...adcom.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Eric Auger <eric.auger@...hat.com>, poza@...eaurora.org,
        Ray Jui <rjui@...adcom.com>
Cc:     bcm-kernel-feedback-list@...adcom.com, linux-pci@...r.kernel.org,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Srinath Mannam <srinath.mannam@...adcom.com>
Subject: [PATCH v6 2/3] iommu/dma: Reserve IOVA for PCIe inaccessible DMA address

The dma_ranges list field of PCI host bridge structure has resource
entries in sorted order representing address ranges allowed for DMA
transfers.

Process the list and reserve IOVA addresses that are not present in its
resource entries (ie DMA memory holes) to prevent allocating IOVA
addresses that cannot be accessed by PCI devices.

Based-on-patch-by: Oza Pawandeep <oza.oza@...adcom.com>
Signed-off-by: Srinath Mannam <srinath.mannam@...adcom.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
Reviewed-by: Oza Pawandeep <poza@...eaurora.org>
Acked-by: Robin Murphy <robin.murphy@....com>
---
 drivers/iommu/dma-iommu.c | 35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 77aabe6..954ae11 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -206,12 +206,13 @@ static int cookie_init_hw_msi_region(struct iommu_dma_cookie *cookie,
 	return 0;
 }
 
-static void iova_reserve_pci_windows(struct pci_dev *dev,
+static int iova_reserve_pci_windows(struct pci_dev *dev,
 		struct iova_domain *iovad)
 {
 	struct pci_host_bridge *bridge = pci_find_host_bridge(dev->bus);
 	struct resource_entry *window;
 	unsigned long lo, hi;
+	phys_addr_t start = 0, end;
 
 	resource_list_for_each_entry(window, &bridge->windows) {
 		if (resource_type(window->res) != IORESOURCE_MEM)
@@ -221,6 +222,31 @@ static void iova_reserve_pci_windows(struct pci_dev *dev,
 		hi = iova_pfn(iovad, window->res->end - window->offset);
 		reserve_iova(iovad, lo, hi);
 	}
+
+	/* Get reserved DMA windows from host bridge */
+	resource_list_for_each_entry(window, &bridge->dma_ranges) {
+		end = window->res->start - window->offset;
+resv_iova:
+		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;
+		/* If window is last entry */
+		if (window->node.next == &bridge->dma_ranges &&
+		    end != ~(dma_addr_t)0) {
+			end = ~(dma_addr_t)0;
+			goto resv_iova;
+		}
+	}
+
+	return 0;
 }
 
 static int iova_reserve_iommu_regions(struct device *dev,
@@ -232,8 +258,11 @@ static int iova_reserve_iommu_regions(struct device *dev,
 	LIST_HEAD(resv_regions);
 	int ret = 0;
 
-	if (dev_is_pci(dev))
-		iova_reserve_pci_windows(to_pci_dev(dev), iovad);
+	if (dev_is_pci(dev)) {
+		ret = iova_reserve_pci_windows(to_pci_dev(dev), iovad);
+		if (ret)
+			return ret;
+	}
 
 	iommu_get_resv_regions(dev, &resv_regions);
 	list_for_each_entry(region, &resv_regions, list) {
-- 
2.7.4