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x86/tsx: Add "auto" option to the tsx= cmdline parameter

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commit 7531a3596e3272d1f6841e0d601a614555dc6b65 upstream.

Platforms which are not affected by X86_BUG_TAA may want the TSX feature
enabled. Add "auto" option to the TSX cmdline parameter. When tsx=auto
disable TSX when X86_BUG_TAA is present, otherwise enable TSX.

More details on X86_BUG_TAA can be found here:
https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/tsx_async_abort.html

 [ bp: Extend the arg buffer to accommodate "auto\0". ]

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: Tony Luck <tony.luck@intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com>
[bwh: Backported to 4.4: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Pawan Gupta 2019-10-23 12:28:57 +02:00 • committed by Greg Kroah-Hartman
parent 5b3b71385e
commit f6eabafe0f
2 changed files with 9 additions and 1 deletions
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3
Documentation/kernel-parameters.txt
View file

@ -4073,6 +4073,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
update. This new MSR allows for the reliable
deactivation of the TSX functionality.)
auto - Disable TSX if X86_BUG_TAA is present,
otherwise enable TSX on the system.
Not specifying this option is equivalent to tsx=off.
See Documentation/hw-vuln/tsx_async_abort.rst

7
arch/x86/kernel/cpu/tsx.c
View file

@ -75,7 +75,7 @@ static bool __init tsx_ctrl_is_supported(void)
void __init tsx_init(void)
{
char arg[4] = {};
char arg[5] = {};
int ret;
if (!tsx_ctrl_is_supported())
@ -87,6 +87,11 @@ void __init tsx_init(void)
tsx_ctrl_state = TSX_CTRL_ENABLE;
} else if (!strcmp(arg, "off")) {
tsx_ctrl_state = TSX_CTRL_DISABLE;
} else if (!strcmp(arg, "auto")) {
if (boot_cpu_has_bug(X86_BUG_TAA))
tsx_ctrl_state = TSX_CTRL_DISABLE;
else
tsx_ctrl_state = TSX_CTRL_ENABLE;
} else {
tsx_ctrl_state = TSX_CTRL_DISABLE;
pr_err("tsx: invalid option, defaulting to off\n");