summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/pci-dma.c
diff options
context:
space:
mode:
authorFenghua Yu <fenghua.yu@intel.com>2009-04-24 17:30:20 -0700
committerDavid Woodhouse <David.Woodhouse@intel.com>2009-04-29 06:54:34 +0100
commit4ed0d3e6c64cfd9ba4ceb2099b10d1cf8ece4320 (patch)
tree950bacfaf57040aafbcc2ea9b52eb171d35c23bd /arch/x86/kernel/pci-dma.c
parent091069740304c979f957ceacec39c461d0192158 (diff)
downloadop-kernel-dev-4ed0d3e6c64cfd9ba4ceb2099b10d1cf8ece4320.zip
op-kernel-dev-4ed0d3e6c64cfd9ba4ceb2099b10d1cf8ece4320.tar.gz
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.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c
index 745579b..8cad0d8 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);
OpenPOWER on IntegriCloud