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. Also use this as an opportunity to draw a line in the sand and add a new interface so as not to introduce any more callers of iommu_capable() which I also want to get rid of. For now it's a quick'n'dirty wrapper function, but will evolve to subsume the internal interface in future. [1] https://docs.microsoft.com/en-us/windows-hardware/design/device-experiences/oem-kernel-dma-protection Suggested-by: Christoph Hellwig <hch@xxxxxx> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx> --- v2: New patch drivers/iommu/intel/iommu.c | 2 ++ include/linux/iommu.h | 7 +++++++ 2 files changed, 9 insertions(+) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 0c7975848972..20d8e1f60068 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -4817,6 +4817,8 @@ 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 4a25f8241207..e16d54e15fee 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 */ @@ -1042,6 +1044,11 @@ static inline size_t iommu_map_sgtable(struct iommu_domain *domain, return iommu_map_sg(domain, iova, sgt->sgl, sgt->orig_nents, prot); } +static inline bool dev_iommu_capable(struct device *dev, enum iommu_cap cap) +{ + return device_iommu_mapped(dev) && iommu_capable(dev->bus, cap); +} + #ifdef CONFIG_IOMMU_DEBUGFS extern struct dentry *iommu_debugfs_dir; void iommu_debugfs_setup(void); -- 2.28.0.dirty
