x86/cpu: Add a "tsx=" cmdline option with TSX disabled by default

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Add a kernel cmdline parameter "tsx" to control the Transactional
Synchronization Extensions (TSX) feature. On CPUs that support TSX
control, use "tsx=on|off" to enable or disable TSX. Not specifying this
option is equivalent to "tsx=off". This is because on certain processors
TSX may be used as a part of a speculative side channel attack.

Carve out the TSX controlling functionality into a separate compilation
unit because TSX is a CPU feature while the TSX async abort control
machinery will go to cpu/bugs.c.

 [ bp: - Massage, shorten and clear the arg buffer.
       - Clarifications of the tsx= possible options - Josh.
       - Expand on TSX_CTRL availability - Pawan. ]

Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>

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This commit is contained in:

Pawan Gupta 2019-10-23 11:01:53 +02:00 • committed by Thomas Gleixner

parent 286836a704

commit 95c5824f75

6 changed files with 175 additions and 1 deletions

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26

Documentation/admin-guide/kernel-parameters.txt

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2

arch/x86/kernel/cpu/Makefile

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2

arch/x86/kernel/cpu/common.c

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16

arch/x86/kernel/cpu/cpu.h

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5

arch/x86/kernel/cpu/intel.c

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125

arch/x86/kernel/cpu/tsx.c

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