AMD iommu is not needed by most users, but enabled by default, and causes performance issue for some device like NICs, so add config option to set amd iommu off as default as Intel
if AMD iommu is needed, it can be enabled by passing amd_iommu=on Signed-off-by: Li RongQing <[email protected]> --- Documentation/admin-guide/kernel-parameters.txt | 1 + arch/x86/configs/x86_64_defconfig | 1 + drivers/iommu/amd/Kconfig | 8 ++++++++ drivers/iommu/amd/init.c | 4 +++- 4 files changed, 13 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 9725c54..0c754c8 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -304,6 +304,7 @@ fullflush - Deprecated, equivalent to iommu.strict=1 off - do not initialize any AMD IOMMU found in the system + on - initialize any AMD IOMMU found in the system force_isolation - Force device isolation for all devices. The IOMMU driver is not allowed anymore to lift isolation diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig index e8a7a0a..0693b62 100644 --- a/arch/x86/configs/x86_64_defconfig +++ b/arch/x86/configs/x86_64_defconfig @@ -218,6 +218,7 @@ CONFIG_EEEPC_LAPTOP=y CONFIG_AMD_IOMMU=y CONFIG_INTEL_IOMMU=y # CONFIG_INTEL_IOMMU_DEFAULT_ON is not set +# CONFIG_AMD_IOMMU_DEFAULT_ON is not set CONFIG_EXT4_FS=y CONFIG_EXT4_FS_POSIX_ACL=y CONFIG_EXT4_FS_SECURITY=y diff --git a/drivers/iommu/amd/Kconfig b/drivers/iommu/amd/Kconfig index a3cbafb..7962c46 100644 --- a/drivers/iommu/amd/Kconfig +++ b/drivers/iommu/amd/Kconfig @@ -32,6 +32,14 @@ config AMD_IOMMU_V2 hardware. Select this option if you want to use devices that support the PCI PRI and PASID interface. +config AMD_IOMMU_DEFAULT_ON + bool "Enable AMD IOMMU by default" + default n + help + Selecting this option will enable a AMD IOMMU at boot time if + one is found. If this option is not selected, AMD IOMMU support can + be enabled by passing amd_iommu=on to the kernel. + config AMD_IOMMU_DEBUGFS bool "Enable AMD IOMMU internals in DebugFS" depends on AMD_IOMMU && IOMMU_DEBUGFS diff --git a/drivers/iommu/amd/init.c b/drivers/iommu/amd/init.c index 1eacd43..dcf24cb 100644 --- a/drivers/iommu/amd/init.c +++ b/drivers/iommu/amd/init.c @@ -155,7 +155,7 @@ int amd_iommu_guest_ir = AMD_IOMMU_GUEST_IR_VAPIC; static int amd_iommu_xt_mode = IRQ_REMAP_XAPIC_MODE; static bool amd_iommu_detected; -static bool amd_iommu_disabled __initdata; +static bool amd_iommu_disabled __initdata = !IS_ENABLED(CONFIG_AMD_IOMMU_DEFAULT_ON); static bool amd_iommu_force_enable __initdata; static int amd_iommu_target_ivhd_type; @@ -3120,6 +3120,8 @@ static int __init parse_amd_iommu_options(char *str) amd_iommu_force_enable = true; if (strncmp(str, "off", 3) == 0) amd_iommu_disabled = true; + if (strncmp(str, "on", 2) == 0) + amd_iommu_disabled = false; if (strncmp(str, "force_isolation", 15) == 0) amd_iommu_force_isolation = true; } -- 2.9.4 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
