linux-kernel - [PATCH AUTOSEL 5.8 51/53] iommu/amd: Do not force direct mapping when SME is active

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Message-Id: <20200907163220.1280412-51-sashal@kernel.org>
Date:   Mon,  7 Sep 2020 12:32:17 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Joerg Roedel <jroedel@...e.de>, Sasha Levin <sashal@...nel.org>,
        iommu@...ts.linux-foundation.org
Subject: [PATCH AUTOSEL 5.8 51/53] 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 2f22326ee4dfe..547b41e376574 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