On Tue, Feb 15, 2022 at 10:19:31AM -0800, Pawan Gupta wrote: > I admit it has gotten complicated with so many bits associated with TSX. Yah, and looka here: https://github.com/andyhhp/xen/commit/ad9f7c3b2e0df38ad6d54f4769d4dccf765fbcee It seems it isn't complicated enough. ;-\ Andy just made me aware of this thing where you guys have added a new MSR bit: MSR_MCU_OPT_CTRL[1] which is called something like MCU_OPT_CTRL_RTM_ALLOW or so. And lemme quote from that patch: /* * Probe for the February 2022 microcode which de-features TSX on * TAA-vulnerable client parts - WHL-R/CFL-R. * * RTM_ALWAYS_ABORT (read above) enumerates the new functionality, * but is read as zero if MCU_OPT_CTRL.RTM_ALLOW has been set * before we run. Undo this. */ so MCU_OPT_CTRL.RTM_ALLOW=1 would have CPUID.X86_FEATURE_RTM_ALWAYS_ABORT=0, which means, we cannot tie TSX disabling on X86_FEATURE_RTM_ALWAYS_ABORT only. So this would need more work, it seems to me. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
