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

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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: David Woodhouse <David.Woodhouse@intel.com>
Cc: stable@vger.kernel.org (which means you can pick up 18436afdc now too)
This commit is contained in:
David Woodhouse 2015-05-11 14:59:20 +01:00
parent b787f68c36
commit 4ed6a540fa
1 changed files with 8 additions and 5 deletions
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13
drivers/iommu/intel-iommu.c
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@ -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)
{ {