On 10/21/19 1:22 PM, speck for Pawan Gupta wrote:
> From: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
> Subject: [PATCH v7 00/10] TAAv7
> 
> Changes since v6:
> - Add Michal's patch to allow tsx=on|off|auto via CONFIG
> - Rebase to v5.4-rc4
> - Changelog, comments and documentation update.
> 
> Changes since v5:
> - Remove unsafe X86_FEATURE_RTM toggles.

I'm wondering if maybe these patches shouldn't touch the cpu
capabilities at all.  After all, even with TSX toggled off, TSX is still
present -- XBEGIN doesn't give #UD.  By making this change, we avoid
needing to even consider what happens when a cpu capability bit changes
after boot.

I think it would be nice to expose whether TSX is enabled somewhere in
sysfs, but I'm not convinced that "features" is the place for it.