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

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Date:   Thu, 16 Feb 2017 09:46:32 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     <linux-arch@...r.kernel.org>, <linux-efi@...r.kernel.org>,
        <kvm@...r.kernel.org>, <linux-doc@...r.kernel.org>,
        <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
        <kasan-dev@...glegroups.com>, <linux-mm@...ck.org>,
        <iommu@...ts.linux-foundation.org>
CC:     Rik van Riel <riel@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Toshimitsu Kani <toshi.kani@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Jonathan Corbet <corbet@....net>,
        Matt Fleming <matt@...eblueprint.co.uk>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Brijesh Singh <brijesh.singh@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        "H. Peter Anvin" <hpa@...or.com>, Borislav Petkov <bp@...en8.de>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Larry Woodman <lwoodman@...hat.com>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: [RFC PATCH v4 20/28] iommu/amd: Disable AMD IOMMU if memory
 encryption is active

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@....com>
---
 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;