From 4ed0d3e6c64cfd9ba4ceb2099b10d1cf8ece4320 Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Fri, 24 Apr 2009 17:30:20 -0700 Subject: 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 Acked-by: Weidong Han Signed-off-by: David Woodhouse --- arch/x86/include/asm/iommu.h | 1 + arch/x86/kernel/pci-dma.c | 6 ++++++ arch/x86/kernel/pci-swiotlb.c | 3 ++- 3 files changed, 9 insertions(+), 1 deletion(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/iommu.h b/arch/x86/include/asm/iommu.h index af326a2975b..fd6d21bbee6 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 745579bc825..8cad0d85424 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 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 221a3853e26..3a0c51e0ba6 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) -- cgit v1.2.3 From aed5d5f4c5ea5da01a774e42cff08c4b4fa59072 Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Thu, 30 Apr 2009 17:57:11 -0700 Subject: Fix !CONFIG_DMAR build failure introduced by Intel IOMMU Pass Through Support This updated patch should fix the compiling errors and remove the extern iommu_pass_through from drivers/pci/intel-iommu.c file. Signed-off-by: Fenghua Yu Signed-off-by: David Woodhouse --- arch/x86/kernel/pci-dma.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index 8cad0d85424..049005e8217 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -32,6 +32,8 @@ int no_iommu __read_mostly; /* Set this to 1 if there is a HW IOMMU in the system */ int iommu_detected __read_mostly = 0; +int iommu_pass_through; + dma_addr_t bad_dma_address __read_mostly = 0; EXPORT_SYMBOL(bad_dma_address); @@ -160,8 +162,6 @@ again: return page_address(page); } -extern int iommu_pass_through; - /* * See for the iommu kernel parameter * documentation. -- cgit v1.2.3