Messages in this thread | | | From | Joerg Roedel <> | Subject | [PATCH 00/10 v2] Cleanup IOMMU passthrough setting (and disable IOMMU Passthrough when SME is active) | Date | Wed, 14 Aug 2019 15:38:31 +0200 |
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Hi,
This patch-set started out small to overwrite the default passthrough setting (through CONFIG_IOMMU_DEFAULT_PASSTHROUGH=y) when SME is active.
But on the way to that Tom reminded me that the current ways to configure passthrough/no-passthrough modes for IOMMU on x86 is a mess. So I added a few more patches to clean that up a bit, getting rid of the iommu_pass_through variable on the way.This information is now kept only in iommu code, with helpers to change that setting from architecture code.
And of course this patch-set still disables IOMMU Passthrough mode when SME is active even when CONFIG_IOMMU_DEFAULT_PASSTHROUGH=y is set.
The reason for that change is that SME with passthrough mode turned out to be fragile with devices requiring SWIOTLB, mainly because SWIOTLB has a maximum allocation size of 256kb and a limit overall size of the bounce buffer.
Therefore having IOMMU in translation mode by default is better when SME is active on a system.
Please review.
Thanks,
Joerg
Changes since v1:
- Cleaned up the kernel command line parameters to configure passthrough/translated mode, getting rid of the global iommu_pass_through variable
Joerg Roedel (10): iommu: Add helpers to set/get default domain type iommu/amd: Request passthrough mode from IOMMU core iommu/vt-d: Request passthrough mode from IOMMU core x86/dma: Get rid of iommu_pass_through ia64: Get rid of iommu_pass_through iommu: Remember when default domain type was set on kernel command line iommu: Print default domain type on boot iommu: Set default domain type at runtime iommu: Disable passthrough mode when SME is active Documentation: Update Documentation for iommu.passthrough
.../admin-guide/kernel-parameters.txt | 2 +- arch/ia64/include/asm/iommu.h | 2 - arch/ia64/kernel/pci-dma.c | 2 - arch/x86/include/asm/iommu.h | 1 - arch/x86/kernel/pci-dma.c | 11 +-- drivers/iommu/amd_iommu.c | 6 +- drivers/iommu/intel-iommu.c | 2 +- drivers/iommu/iommu.c | 83 +++++++++++++++++-- include/linux/iommu.h | 16 ++++ 9 files changed, 101 insertions(+), 24 deletions(-)
-- 2.17.1
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