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Commit fade1ec0 authored by Robin Murphy's avatar Robin Murphy Committed by Will Deacon
Browse files

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: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent 44bb7e24

arch/arm64/mm/dma-mapping.c

+1 −1
Original line number Diff line number Diff line
@@ -827,7 +827,7 @@ static bool do_iommu_attach(struct device *dev, const struct iommu_ops *ops, 
	 * then the IOMMU core will have already configured a group for this

	 * device, and allocated the default domain for that group.

	 */

	if (!domain || iommu_dma_init_domain(domain, dma_base, size)) {

	if (!domain || iommu_dma_init_domain(domain, dma_base, size, dev)) {

		pr_warn("Failed to set up IOMMU for device %s; retaining platform DMA ops\n",

			dev_name(dev));

		return false;

drivers/gpu/drm/exynos/exynos_drm_iommu.h

+1 −1
Original line number Diff line number Diff line
@@ -66,7 +66,7 @@ static inline int __exynos_iommu_create_mapping(struct exynos_drm_private *priv, 
	if (ret)

		goto free_domain;



	ret = iommu_dma_init_domain(domain, start, size);

	ret = iommu_dma_init_domain(domain, start, size, NULL);

	if (ret)

		goto put_cookie;

drivers/iommu/dma-iommu.c

+24 −1
Original line number Diff line number Diff line
@@ -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;

}

include/linux/dma-iommu.h

+2 −1
Original line number Diff line number Diff line
@@ -30,7 +30,8 @@ int iommu_get_dma_cookie(struct iommu_domain *domain); 
void iommu_put_dma_cookie(struct iommu_domain *domain);



/* Setup call for arch DMA mapping code */

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);



/* General helpers for DMA-API <-> IOMMU-API interaction */

int dma_direction_to_prot(enum dma_data_direction dir, bool coherent);