Merge branches 'core-objtool-for-linus', 'x86-cleanups-for-linus' and 'x86-apic-for...

[platform/kernel/linux-rpi.git] / arch / x86 / Kconfig

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 4d27bdc..99c3ddd 100644 (file)
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -24,7 +24,7 @@ config X86_64
        depends on 64BIT
        # Options that are inherently 64-bit kernel only:
        select ARCH_HAS_GIGANTIC_PAGE
-       select ARCH_SUPPORTS_INT128
+       select ARCH_SUPPORTS_INT128 if CC_HAS_INT128
        select ARCH_USE_CMPXCHG_LOCKREF
        select HAVE_ARCH_SOFT_DIRTY
        select MODULES_USE_ELF_RELA
@@ -1910,6 +1910,51 @@ config X86_INTEL_MEMORY_PROTECTION_KEYS
 
          If unsure, say y.
 
+choice
+       prompt "TSX enable mode"
+       depends on CPU_SUP_INTEL
+       default X86_INTEL_TSX_MODE_OFF
+       help
+         Intel's TSX (Transactional Synchronization Extensions) feature
+         allows to optimize locking protocols through lock elision which
+         can lead to a noticeable performance boost.
+
+         On the other hand it has been shown that TSX can be exploited
+         to form side channel attacks (e.g. TAA) and chances are there
+         will be more of those attacks discovered in the future.
+
+         Therefore TSX is not enabled by default (aka tsx=off). An admin
+         might override this decision by tsx=on the command line parameter.
+         Even with TSX enabled, the kernel will attempt to enable the best
+         possible TAA mitigation setting depending on the microcode available
+         for the particular machine.
+
+         This option allows to set the default tsx mode between tsx=on, =off
+         and =auto. See Documentation/admin-guide/kernel-parameters.txt for more
+         details.
+
+         Say off if not sure, auto if TSX is in use but it should be used on safe
+         platforms or on if TSX is in use and the security aspect of tsx is not
+         relevant.
+
+config X86_INTEL_TSX_MODE_OFF
+       bool "off"
+       help
+         TSX is disabled if possible - equals to tsx=off command line parameter.
+
+config X86_INTEL_TSX_MODE_ON
+       bool "on"
+       help
+         TSX is always enabled on TSX capable HW - equals the tsx=on command
+         line parameter.
+
+config X86_INTEL_TSX_MODE_AUTO
+       bool "auto"
+       help
+         TSX is enabled on TSX capable HW that is believed to be safe against
+         side channel attacks- equals the tsx=auto command line parameter.
+endchoice
+
 config EFI
        bool "EFI runtime service support"
        depends on ACPI