On Tue, 2022-11-22 at 20:33 +0100, Peter Zijlstra wrote: > On Tue, Nov 22, 2022 at 11:24:48AM -0800, Dave Hansen wrote: > > > > Not intialize TDX on busy NOHZ_FULL cpus and hard-limit the cpumask of > > > all TDX using tasks. > > > > I don't think that works. As I mentioned to Thomas elsewhere, you don't > > just need to initialize TDX on the CPUs where it is used. Before the > > module will start working you need to initialize it on *all* the CPUs it > > knows about. The module itself has a little counter where it tracks > > this and will refuse to start being useful until it gets called > > thoroughly enough. > > That's bloody terrible, that is. How are we going to make that work with > the SMT mitigation crud that forces the SMT sibilng offline? > > Then the counters don't match and TDX won't work. > > Can we get this limitiation removed and simply let the module throw a > wobbly (error) when someone tries and use TDX without that logical CPU > having been properly initialized? Dave kindly helped to raise this issue and I'll follow up with TDX module guys to see whether we can remove/ease such limitation. Thanks!
