[PATCH v1 0/3] iommu/vt-d: real DMA sub-device info allocation

Jon Derrick jonathan.derrick at intel.com
Wed May 27 16:56:14 UTC 2020

This set adds the support for real DMA sub-devices to have device_domain_info,
leading to the correct domain type being used.

This applies on Joerg's origin/next. This also applies against v5.6.12
and v5.7-rc7 with some API modifications, making it a stable candidate
that fixes the issue reported in [1].

For v5.6.12 and v5.7-rc7, identity_mapping() would return 0 for real DMA
sub-devices due to not having valid device_domain_info, leading to
__intel_map_single() paths. This is a problem if the real DMA device
started in IDENTITY, leading to a NULL Pointer Dereference:

		domain = find_domain(dev);
			dev = &pci_real_dma_dev(to_pci_dev(dev))->dev;
			info = dev->archdata.iommu;
			return info->domain;

		iommu = domain_get_iommu(domain)
			if (WARN_ON(domain->domain.type != IOMMU_DOMAIN_DMA))
				return NULL;

		cap_zlr(iommu->cap) <-- NULL Pointer Deref

This issue was also fixed by 6fc7020cf298 ("iommu/vt-d: Apply per-device
dma_ops") due to removing identity_mapping() paths.

[1] https://bugzilla.kernel.org/show_bug.cgi?id=207575

Jon Derrick (3):
  iommu/vt-d: Only clear real DMA device's context entries
  iommu/vt-d: Allocate domain info for real DMA sub-devices
  iommu/vt-d: Remove real DMA lookup in find_domain

 drivers/iommu/intel-iommu.c | 31 +++++++++++++++++++++++--------
 include/linux/intel-iommu.h |  1 +
 2 files changed, 24 insertions(+), 8 deletions(-)


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