diff options
| -rw-r--r-- | drivers/iommu/intel-iommu.c | 49 |
1 files changed, 39 insertions, 10 deletions
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c index 58cc2b75d7ae..d1f5caad04f9 100644 --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -2543,22 +2543,46 @@ static bool device_has_rmrr(struct device *dev) return false; } +/* + * There are a couple cases where we need to restrict the functionality of + * devices associated with RMRRs. The first is when evaluating a device for + * identity mapping because problems exist when devices are moved in and out + * of domains and their respective RMRR information is lost. This means that + * a device with associated RMRRs will never be in a "passthrough" domain. + * The second is use of the device through the IOMMU API. This interface + * expects to have full control of the IOVA space for the device. We cannot + * satisfy both the requirement that RMRR access is maintained and have an + * unencumbered IOVA space. We also have no ability to quiesce the device's + * use of the RMRR space or even inform the IOMMU API user of the restriction. + * We therefore prevent devices associated with an RMRR from participating in + * the IOMMU API, which eliminates them from device assignment. + * + * In both cases we assume that PCI USB devices with RMRRs have them largely + * for historical reasons and that the RMRR space is not actively used post + * boot. This exclusion may change if vendors begin to abuse it. + */ +static bool device_is_rmrr_locked(struct device *dev) +{ + if (!device_has_rmrr(dev)) + return false; + + if (dev_is_pci(dev)) { + struct pci_dev *pdev = to_pci_dev(dev); + + if ((pdev->class >> 8) == PCI_CLASS_SERIAL_USB) + return false; + } + + return true; +} + static int iommu_should_identity_map(struct device *dev, int startup) { if (dev_is_pci(dev)) { struct pci_dev *pdev = to_pci_dev(dev); - /* - * We want to prevent any device associated with an RMRR from - * getting placed into the SI Domain. This is done because - * problems exist when devices are moved in and out of domains - * and their respective RMRR info is lost. We exempt USB devices - * from this process due to their usage of RMRRs that are known - * to not be needed after BIOS hand-off to OS. - */ - if (device_has_rmrr(dev) && - (pdev->class >> 8) != PCI_CLASS_SERIAL_USB) + if (device_is_rmrr_locked(dev)) return 0; if ((iommu_identity_mapping & IDENTMAP_AZALIA) && IS_AZALIA(pdev)) @@ -4221,6 +4245,11 @@ static int intel_iommu_attach_device(struct iommu_domain *domain, int addr_width; u8 bus, devfn; + if (device_is_rmrr_locked(dev)) { + dev_warn(dev, "Device is ineligible for IOMMU domain attach due to platform RMRR requirement. Contact your platform vendor.\n"); + return -EPERM; + } + /* normally dev is not mapped */ if (unlikely(domain_context_mapped(dev))) { struct dmar_domain *old_domain; |