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Commit 4ed6a540 authored by David Woodhouse's avatar David Woodhouse
Browse files

iommu/vt-d: Fix passthrough mode with translation-disabled devices 



When we use 'intel_iommu=igfx_off' to disable translation for the
graphics, and when we discover that the BIOS has misconfigured the DMAR
setup for I/OAT, we use a special DUMMY_DEVICE_DOMAIN_INFO value in
dev->archdata.iommu to indicate that translation is disabled.

With passthrough mode, we were attempting to dereference that as a
normal pointer to a struct device_domain_info when setting up an
identity mapping for the affected device.

This fixes the problem by making device_to_iommu() explicitly check for
the special value and indicate that no IOMMU was found to handle the
devices in question.

Signed-off-by: default avatarDavid Woodhouse <David.Woodhouse@intel.com>
Cc: stable@vger.kernel.org (which means you can pick up 18436afd now too)
parent b787f68c

drivers/iommu/intel-iommu.c

+8 −5
Original line number Original line Diff line number Diff line
@@ -696,6 +696,11 @@ static inline struct context_entry *iommu_context_addr(struct intel_iommu *iommu 
	return &context[devfn];

	return &context[devfn];

}

}





static int iommu_dummy(struct device *dev)

{

	return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;

}



static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn)

static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn)

{

{

	struct dmar_drhd_unit *drhd = NULL;

	struct dmar_drhd_unit *drhd = NULL;
@@ -705,6 +710,9 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf 
	u16 segment = 0;

	u16 segment = 0;

	int i;

	int i;





	if (iommu_dummy(dev))

		return NULL;



	if (dev_is_pci(dev)) {

	if (dev_is_pci(dev)) {

		pdev = to_pci_dev(dev);

		pdev = to_pci_dev(dev);

		segment = pci_domain_nr(pdev->bus);

		segment = pci_domain_nr(pdev->bus);
@@ -2969,11 +2977,6 @@ static inline struct dmar_domain *get_valid_domain_for_dev(struct device *dev) 
	return __get_valid_domain_for_dev(dev);

	return __get_valid_domain_for_dev(dev);

}

}





static int iommu_dummy(struct device *dev)

{

	return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;

}



/* Check if the dev needs to go through non-identity map and unmap process.*/

/* Check if the dev needs to go through non-identity map and unmap process.*/

static int iommu_no_mapping(struct device *dev)

static int iommu_no_mapping(struct device *dev)

{

{