Commit d0be55fb authored by Robin Murphy's avatar Robin Murphy Committed by Joerg Roedel
Browse files

iommu: Add capability for pre-boot DMA protection 

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: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: default avatarRobin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/d6218dff2702472da80db6aec2c9589010684551.1650878781.git.robin.murphy@arm.com


Signed-off-by: default avatarJoerg Roedel <jroedel@suse.de>
parent ed36d04e

drivers/iommu/intel/iommu.c

+2 −0
Original line number Diff line number Diff line
@@ -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;

}

include/linux/iommu.h

+2 −0
Original line number Diff line number Diff line
@@ -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 */