diff options
Diffstat (limited to 'drivers/thunderbolt/nhi.c')
| -rw-r--r-- | drivers/thunderbolt/nhi.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c index 4a582183f675..4bc87b0f003a 100644 --- a/drivers/thunderbolt/nhi.c +++ b/drivers/thunderbolt/nhi.c @@ -15,9 +15,11 @@ #include <linux/pci.h> #include <linux/dma-mapping.h> #include <linux/interrupt.h> +#include <linux/iommu.h> #include <linux/module.h> #include <linux/delay.h> #include <linux/property.h> +#include <linux/string_helpers.h> #include "nhi.h" #include "nhi_regs.h" @@ -1103,6 +1105,47 @@ static void nhi_check_quirks(struct tb_nhi *nhi) nhi->quirks |= QUIRK_AUTO_CLEAR_INT; } +static int nhi_check_iommu_pdev(struct pci_dev *pdev, void *data) +{ + if (!pdev->external_facing || + !device_iommu_capable(&pdev->dev, IOMMU_CAP_PRE_BOOT_PROTECTION)) + return 0; + *(bool *)data = true; + return 1; /* Stop walking */ +} + +static void nhi_check_iommu(struct tb_nhi *nhi) +{ + struct pci_bus *bus = nhi->pdev->bus; + bool port_ok = false; + + /* + * Ideally what we'd do here is grab every PCI device that + * represents a tunnelling adapter for this NHI and check their + * status directly, but unfortunately USB4 seems to make it + * obnoxiously difficult to reliably make any correlation. + * + * So for now we'll have to bodge it... Hoping that the system + * is at least sane enough that an adapter is in the same PCI + * segment as its NHI, if we can find *something* on that segment + * which meets the requirements for Kernel DMA Protection, we'll + * take that to imply that firmware is aware and has (hopefully) + * done the right thing in general. We need to know that the PCI + * layer has seen the ExternalFacingPort property which will then + * inform the IOMMU layer to enforce the complete "untrusted DMA" + * flow, but also that the IOMMU driver itself can be trusted not + * to have been subverted by a pre-boot DMA attack. + */ + while (bus->parent) + bus = bus->parent; + + pci_walk_bus(bus, nhi_check_iommu_pdev, &port_ok); + + nhi->iommu_dma_protection = port_ok; + dev_dbg(&nhi->pdev->dev, "IOMMU DMA protection is %s\n", + str_enabled_disabled(port_ok)); +} + static int nhi_init_msi(struct tb_nhi *nhi) { struct pci_dev *pdev = nhi->pdev; @@ -1220,6 +1263,7 @@ static int nhi_probe(struct pci_dev *pdev, const struct pci_device_id *id) return -ENOMEM; nhi_check_quirks(nhi); + nhi_check_iommu(nhi); res = nhi_init_msi(nhi); if (res) { |