[RFC PATCH v4 20/28] iommu/amd: Disable AMD IOMMU if memory encryption is active

[Tom Lendacky <thomas.lendacky@xxxxxxx>]

For now, disable the AMD IOMMU if memory encryption is active. A future
patch will re-enable the function with full memory encryption support.

Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
---
 drivers/iommu/amd_iommu_init.c |    7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 6799cf9..6df2dd5 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -29,6 +29,7 @@
 #include <linux/export.h>
 #include <linux/iommu.h>
 #include <linux/kmemleak.h>
+#include <linux/mem_encrypt.h>
 #include <asm/pci-direct.h>
 #include <asm/iommu.h>
 #include <asm/gart.h>
@@ -2544,6 +2545,12 @@ int __init amd_iommu_detect(void)
 	if (amd_iommu_disabled)
 		return -ENODEV;
 
+	/* For now, disable the IOMMU if SME is active */
+	if (sme_active()) {
+		pr_notice("AMD-Vi: SME is active, disabling the IOMMU\n");
+		return -ENODEV;
+	}
+
 	ret = iommu_go_to_state(IOMMU_IVRS_DETECTED);
 	if (ret)
 		return ret;