VT-d's dmar_platform_optin() actually represents a combination of properties fairly well standardised by Microsoft as "Pre-boot DMA Protection" and "Kernel DMA Protection"[1]. As such, we can provide interested consumers with an abstracted capability rather than driver-specific interfaces that won't scale. We name it for the former aspect since that's what external callers are most likely to be interested in; the latter is for the IOMMU layer to handle itself. [1] https://docs.microsoft.com/en-us/windows-hardware/design/device-experiences/oem-kernel-dma-protection Suggested-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx> --- v4: No change drivers/iommu/intel/iommu.c | 2 ++ include/linux/iommu.h | 2 ++ 2 files changed, 4 insertions(+) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index df5c62ecf942..0edf6084dc14 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -4551,6 +4551,8 @@ static bool intel_iommu_capable(enum iommu_cap cap) return domain_update_iommu_snooping(NULL); if (cap == IOMMU_CAP_INTR_REMAP) return irq_remapping_enabled == 1; + if (cap == IOMMU_CAP_PRE_BOOT_PROTECTION) + return dmar_platform_optin(); return false; } diff --git a/include/linux/iommu.h b/include/linux/iommu.h index e26cf84e5d82..4123693ae319 100644 --- a/include/linux/iommu.h +++ b/include/linux/iommu.h @@ -107,6 +107,8 @@ enum iommu_cap { transactions */ IOMMU_CAP_INTR_REMAP, /* IOMMU supports interrupt isolation */ IOMMU_CAP_NOEXEC, /* IOMMU_NOEXEC flag */ + IOMMU_CAP_PRE_BOOT_PROTECTION, /* Firmware says it used the IOMMU for + DMA protection and we should too */ }; /* These are the possible reserved region types */ -- 2.35.3.dirty
