iommu/dma: Avoid PCI host bridge windows

With our DMA ops enabled for PCI devices, we should avoid allocating
IOVAs which a host bridge might misinterpret as peer-to-peer DMA and
lead to faults, corruption or other badness. To be safe, punch out holes
for all of the relevant host bridge's windows when initialising a DMA
domain for a PCI device.

CC: Marek Szyprowski <m.szyprowski@samsung.com>
CC: Inki Dae <inki.dae@samsung.com>
Reported-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 24 insertions, 1 deletions

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 4329d18080cf..c5ab8667e6f2 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -27,6 +27,7 @@
 #include <linux/iova.h>
 #include <linux/irq.h>
 #include <linux/mm.h>
+#include <linux/pci.h>
 #include <linux/scatterlist.h>
 #include <linux/vmalloc.h>
 
@@ -103,18 +104,38 @@ void iommu_put_dma_cookie(struct iommu_domain *domain)
 }
 EXPORT_SYMBOL(iommu_put_dma_cookie);
 
+static void 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;
+
+	resource_list_for_each_entry(window, &bridge->windows) {
+		if (resource_type(window->res) != IORESOURCE_MEM &&
+		    resource_type(window->res) != IORESOURCE_IO)
+			continue;
+
+		lo = iova_pfn(iovad, window->res->start - window->offset);
+		hi = iova_pfn(iovad, window->res->end - window->offset);
+		reserve_iova(iovad, lo, hi);
+	}
+}
+
 /**
  * iommu_dma_init_domain - Initialise a DMA mapping domain
  * @domain: IOMMU domain previously prepared by iommu_get_dma_cookie()
  * @base: IOVA at which the mappable address space starts
  * @size: Size of IOVA space
+ * @dev: Device the domain is being initialised for
  *
  * @base and @size should be exact multiples of IOMMU page granularity to
  * avoid rounding surprises. If necessary, we reserve the page at address 0
  * to ensure it is an invalid IOVA. It is safe to reinitialise a domain, but
  * any change which could make prior IOVAs invalid will fail.
  */
-int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base, u64 size)
+int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base,
+		u64 size, struct device *dev)
 {
 	struct iova_domain *iovad = cookie_iovad(domain);
 	unsigned long order, base_pfn, end_pfn;
@@ -152,6 +173,8 @@ int iommu_dma_init_domain(struct iommu_domain *domain, dma_addr_t base, u64 size
 		iovad->dma_32bit_pfn = end_pfn;
 	} else {
 		init_iova_domain(iovad, 1UL << order, base_pfn, end_pfn);
+		if (dev && dev_is_pci(dev))
+			iova_reserve_pci_windows(to_pci_dev(dev), iovad);
 	}
 	return 0;
 }