diff options
| author | Fenghua Yu <fenghua.yu@intel.com> | 2009-04-24 17:30:20 -0700 |
|---|---|---|
| committer | David Woodhouse <David.Woodhouse@intel.com> | 2009-04-29 06:54:34 +0100 |
| commit | 4ed0d3e6c64cfd9ba4ceb2099b10d1cf8ece4320 (patch) | |
| tree | 950bacfaf57040aafbcc2ea9b52eb171d35c23bd /arch/x86 | |
| parent | 091069740304c979f957ceacec39c461d0192158 (diff) | |
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')
| -rw-r--r-- | arch/x86/include/asm/iommu.h | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/pci-dma.c | 6 | ||||
| -rw-r--r-- | arch/x86/kernel/pci-swiotlb.c | 3 |
3 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h index af326a2975b5..fd6d21bbee6c 100644 --- a/arch/x86/include/asm/iommu.h +++ b/arch/x86/include/asm/iommu.h @@ -6,6 +6,7 @@ extern void no_iommu_init(void); extern struct dma_map_ops nommu_dma_ops; extern int force_iommu, no_iommu; extern int iommu_detected; +extern int iommu_pass_through; /* 10 seconds */ #define DMAR_OPERATION_TIMEOUT ((cycles_t) tsc_khz*10*1000) 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); diff --git a/arch/x86/kernel/pci-swiotlb.c b/arch/x86/kernel/pci-swiotlb.c index 221a3853e268..3a0c51e0ba6d 100644 --- a/arch/x86/kernel/pci-swiotlb.c +++ b/arch/x86/kernel/pci-swiotlb.c @@ -71,7 +71,8 @@ void __init pci_swiotlb_init(void) { /* don't initialize swiotlb if iommu=off (no_iommu=1) */ #ifdef CONFIG_X86_64 - if (!iommu_detected && !no_iommu && max_pfn > MAX_DMA32_PFN) + if ((!iommu_detected && !no_iommu && max_pfn > MAX_DMA32_PFN) || + iommu_pass_through) swiotlb = 1; #endif if (swiotlb_force) |