diff options
author | Fenghua Yu <fenghua.yu@intel.com> | 2009-04-25 02:30:20 +0200 |
---|---|---|
committer | David Woodhouse <David.Woodhouse@intel.com> | 2009-04-29 07:54:34 +0200 |
commit | 4ed0d3e6c64cfd9ba4ceb2099b10d1cf8ece4320 (patch) | |
tree | 950bacfaf57040aafbcc2ea9b52eb171d35c23bd /arch/x86/kernel/pci-dma.c | |
parent | Linux 2.6.30-rc3 (diff) | |
download | linux-4ed0d3e6c64cfd9ba4ceb2099b10d1cf8ece4320.tar.xz linux-4ed0d3e6c64cfd9ba4ceb2099b10d1cf8ece4320.zip |
Intel IOMMU Pass Through Support
The patch adds kernel parameter intel_iommu=pt to set up pass through
mode in context mapping entry. This disables DMAR in linux kernel; but
KVM still runs on VT-d and interrupt remapping still works.
In this mode, kernel uses swiotlb for DMA API functions but other VT-d
functionalities are enabled for KVM. KVM always uses multi level
translation page table in VT-d. By default, pass though mode is disabled
in kernel.
This is useful when people don't want to enable VT-d DMAR in kernel but
still want to use KVM and interrupt remapping for reasons like DMAR
performance concern or debug purpose.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Acked-by: Weidong Han <weidong@intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'arch/x86/kernel/pci-dma.c')
-rw-r--r-- | arch/x86/kernel/pci-dma.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index 745579bc8256..8cad0d854242 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -160,6 +160,8 @@ again: return page_address(page); } +extern int iommu_pass_through; + /* * See <Documentation/x86_64/boot-options.txt> for the iommu kernel parameter * documentation. @@ -209,6 +211,10 @@ static __init int iommu_setup(char *p) #ifdef CONFIG_SWIOTLB if (!strncmp(p, "soft", 4)) swiotlb = 1; + if (!strncmp(p, "pt", 2)) { + iommu_pass_through = 1; + return 1; + } #endif gart_parse_options(p); |