linux-kernel - [PATCH 5.8 106/177] iommu/amd: Do not force direct mapping when SME is active

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Message-Id: <20200915140658.731123376@linuxfoundation.org>
Date:   Tue, 15 Sep 2020 16:12:57 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Joerg Roedel <jroedel@...e.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.8 106/177] iommu/amd: Do not force direct mapping when SME is active

From: Joerg Roedel <jroedel@...e.de>

[ Upstream commit 7cad554887f1c5fd77e57e6bf4be38370c2160cb ]

Do not force devices supporting IOMMUv2 to be direct mapped when memory
encryption is active. This might cause them to be unusable because their
DMA mask does not include the encryption bit.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
Link: https://lore.kernel.org/r/20200824105415.21000-2-joro@8bytes.org
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/iommu/amd/iommu.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 200ee948f6ec1..37c74c842f3a3 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -2650,7 +2650,12 @@ static int amd_iommu_def_domain_type(struct device *dev)
 	if (!dev_data)
 		return 0;
 
-	if (dev_data->iommu_v2)
+	/*
+	 * Do not identity map IOMMUv2 capable devices when memory encryption is
+	 * active, because some of those devices (AMD GPUs) don't have the
+	 * encryption bit in their DMA-mask and require remapping.
+	 */
+	if (!mem_encrypt_active() && dev_data->iommu_v2)
 		return IOMMU_DOMAIN_IDENTITY;
 
 	return 0;
-- 
2.25.1