Commit e2be2a83 authored Nov 25, 2020 by Lu Baolu Committed by Will Deacon Nov 25, 2020

x86/tboot: Don't disable swiotlb when iommu is forced on

After commit 327d5b2f ("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: 327d5b2f ("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>

parent 77c38c8c

arch/x86/kernel/tboot.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -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;
		#ifdef CONFIG_SWIOTLB
		swiotlb = 0;
		#endif
		no_iommu = 0;

		return 1;