From 2cc13bb4f59fa7e66acf5b1b78bdf97d73d3416a Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Mon, 19 Aug 2019 15:22:55 +0200 Subject: [PATCH] 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 Tested-by: Tom Lendacky Signed-off-by: Joerg Roedel --- drivers/iommu/iommu.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 9ad1b0af2306..0f585b614657 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -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",