From 58d1131777a4b7c228267b809bd88f7be66edcfb Mon Sep 17 00:00:00 2001 From: Olof Johansson Date: Fri, 20 Jul 2018 11:02:23 -0700 Subject: iommu: Add config option to set passthrough as default This allows the default behavior to be controlled by a kernel config option instead of changing the commandline for the kernel to include "iommu.passthrough=on" or "iommu=pt" on machines where this is desired. Likewise, for machines where this config option is enabled, it can be disabled at boot time with "iommu.passthrough=off" or "iommu=nopt". Also corrected iommu=pt documentation for IA-64, since it has no code that parses iommu= at all. Signed-off-by: Olof Johansson Signed-off-by: Joerg Roedel --- arch/x86/kernel/pci-dma.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/x86/kernel/pci-dma.c') diff --git a/arch/x86/kernel/pci-dma.c b/arch/x86/kernel/pci-dma.c index ab5d9dd668d2..0acb135de7fb 100644 --- a/arch/x86/kernel/pci-dma.c +++ b/arch/x86/kernel/pci-dma.c @@ -40,8 +40,14 @@ int iommu_detected __read_mostly = 0; * devices and allow every device to access to whole physical memory. This is * useful if a user wants to use an IOMMU only for KVM device assignment to * guests and not for driver dma translation. + * It is also possible to disable by default in kernel config, and enable with + * iommu=nopt at boot time. */ +#ifdef CONFIG_IOMMU_DEFAULT_PASSTHROUGH +int iommu_pass_through __read_mostly = 1; +#else int iommu_pass_through __read_mostly; +#endif extern struct iommu_table_entry __iommu_table[], __iommu_table_end[]; @@ -135,6 +141,8 @@ static __init int iommu_setup(char *p) #endif if (!strncmp(p, "pt", 2)) iommu_pass_through = 1; + if (!strncmp(p, "nopt", 4)) + iommu_pass_through = 0; gart_parse_options(p); -- cgit v1.2.1