Commit 2cc13bb4 authored Aug 19, 2019 by Joerg Roedel

iommu: Disable passthrough mode when SME is active



Using Passthrough mode when SME is active causes certain
devices to use the SWIOTLB bounce buffer. The bounce buffer
code has an upper limit of 256kb for the size of DMA
allocations, which is too small for certain devices and
causes them to fail.

With this patch we enable IOMMU by default when SME is
active in the system, making the default configuration work
for more systems than it does now.

Users that don't want IOMMUs to be enabled still can disable
them with kernel parameters.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

parent 22bb182c

drivers/iommu/iommu.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -119,6 +119,11 @@ static int __init iommu_subsys_init(void)
		iommu_set_default_passthrough(false);
		else
		iommu_set_default_translated(false);

		if (iommu_default_passthrough() && sme_active()) {
		pr_info("SME detected - Disabling default IOMMU Passthrough\n");
		iommu_set_default_translated(false);
		}
		}

		pr_info("Default domain type: %s %s\n",

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