From: Joerg Roedel <jroedel@suse.de>
Date: Fri, 9 Aug 2019 16:24:33 +0200
Subject: [PATCH 10/11] iommu: Disable passthrough mode when SME is active
Patch-mainline: v5.4-rc1
Git-commit: 2cc13bb4f59fa7e66acf5b1b78bdf97d73d3416a
References: bsc#1136039

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>
---
 drivers/iommu/iommu.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -133,6 +133,11 @@ 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",