Commit 0100065e authored by David Woodhouse's avatar David Woodhouse Committed by Kamal Mostafa

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

commit 4ed6a540 upstream.

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>
Signed-off-by: default avatarKamal Mostafa <kamal@canonical.com>
parent bda553e5
......@@ -681,6 +681,11 @@ static void domain_update_iommu_cap(struct dmar_domain *domain)
domain->iommu_superpage = domain_update_iommu_superpage(NULL);
}
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)
{
struct dmar_drhd_unit *drhd = NULL;
......@@ -690,6 +695,9 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf
u16 segment = 0;
int i;
if (iommu_dummy(dev))
return NULL;
if (dev_is_pci(dev)) {
pdev = to_pci_dev(dev);
segment = pci_domain_nr(pdev->bus);
......@@ -2981,11 +2989,6 @@ static inline struct dmar_domain *get_valid_domain_for_dev(struct device *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.*/
static int iommu_no_mapping(struct device *dev)
{
......
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