[5.9,118/152] x86/tboot: Dont disable swiotlb when iommu is forced on
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Message ID 20201201084727.257311425@linuxfoundation.org
State New, archived
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  • Untitled series #474541
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Commit Message

Greg Kroah-Hartman Dec. 1, 2020, 8:53 a.m. UTC
From: Lu Baolu <baolu.lu@linux.intel.com>

[ Upstream commit e2be2a833ab5338fa5b8b99ba622b911d96f1795 ]

After commit 327d5b2fee91c ("iommu/vt-d: Allow 32bit devices to uses DMA
domain"), swiotlb could also be used for direct memory access if IOMMU
is enabled but a device is configured to pass through the DMA translation.
Keep swiotlb when IOMMU is forced on, otherwise, some devices won't work
if "iommu=pt" kernel parameter is used.

Fixes: 327d5b2fee91 ("iommu/vt-d: Allow 32bit devices to uses DMA domain")
Reported-and-tested-by: Adrian Huang <ahuang12@lenovo.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Link: https://lore.kernel.org/r/20201125014124.4070776-1-baolu.lu@linux.intel.com
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=210237
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
 arch/x86/kernel/tboot.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff mbox series

diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index 420be871d9d45..ae64f98ec2ab6 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -514,13 +514,10 @@  int tboot_force_iommu(void)
 	if (!tboot_enabled())
 		return 0;
-	if (no_iommu || swiotlb || dmar_disabled)
+	if (no_iommu || dmar_disabled)
 		pr_warn("Forcing Intel-IOMMU to enabled\n");
 	dmar_disabled = 0;
-	swiotlb = 0;
 	no_iommu = 0;
 	return 1;