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 --- drivers/pci/dmar.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'drivers/pci/dmar.c') diff --git a/drivers/pci/dmar.c b/drivers/pci/dmar.c index fa3a11365ec..d3d86b749ee 100644 --- a/drivers/pci/dmar.c +++ b/drivers/pci/dmar.c @@ -515,6 +515,7 @@ int alloc_iommu(struct dmar_drhd_unit *drhd) u32 ver; static int iommu_allocated = 0; int agaw = 0; + int msagaw = 0; iommu = kzalloc(sizeof(*iommu), GFP_KERNEL); if (!iommu) @@ -535,12 +536,20 @@ int alloc_iommu(struct dmar_drhd_unit *drhd) agaw = iommu_calculate_agaw(iommu); if (agaw < 0) { printk(KERN_ERR - "Cannot get a valid agaw for iommu (seq_id = %d)\n", + "Cannot get a valid agaw for iommu (seq_id = %d)\n", + iommu->seq_id); + goto error; + } + msagaw = iommu_calculate_max_sagaw(iommu); + if (msagaw < 0) { + printk(KERN_ERR + "Cannot get a valid max agaw for iommu (seq_id = %d)\n", iommu->seq_id); goto error; } #endif iommu->agaw = agaw; + iommu->msagaw = msagaw; /* the registers might be more than one page */ map_size = max_t(int, ecap_max_iotlb_offset(iommu->ecap), -- cgit v1.2.3