On Fri, Jun 12, 2020 at 07:48:01PM +0200, Borislav Petkov wrote: > On Fri, Jun 12, 2020 at 10:20:03AM -0700, Linus Torvalds wrote: > > Since you already added the filtering, this looks fairly sane. > > > > IOW, what MSR's do we expect people to maybe write to normally? You > > added MSR_IA32_ENERGY_PERF_BIAS as an allowed MST, maybe there are > > others? > > Right, this MSR is being written by cpupower in tools/. My search was > confined within the kernel source only so there very likely are others.
So that tool writing to /dev/msr has already caused pain; the direct result is that the intel pstate driver doesn't want to use an MSR shadow variable to avoid RDMSR because that'd loose input. https://lkml.org/lkml/2019/3/25/310 (sorry, that's what google found me) So ideally we'd just disallow it too. It already has a sysfs file (per those patches): Documentation/admin-guide/pm/intel_epb.rst
