On Sat, Apr 10 2021 at 11:47, Borislav Petkov wrote: > On Sat, Apr 10, 2021 at 11:27:11AM +0200, Thomas Gleixner wrote: >> On Tue, Mar 30 2021 at 16:25, Feng Tang wrote: >> > Normally the tsc_sync will be checked every time system enters idle state, >> > but there is still caveat that a system won't enter idle, either because >> > it's too busy or configured purposely to not enter idle. Setup a periodic >> > timer to make sure the check is always on. >> >> Bah. I really hate the fact that we don't have a knob to disable writes >> to the TSC/TSC_ADJUST msrs. That would spare this business alltogether. > > We have the MSR filtering and I'd *love* to add those MSRs to a > permanent ban list of MSRs which will never ever be written to from > luserspace.
That's good, but what I really want is a knob which prevents BIOS/SMM from writing to it. The only reason why BIOS ever needs to write is for physical hotplug and perhaps for 4+ socket machines on boot. After that every write is a bug. Thanks, tglx