On Fri, Apr 26, 2019 at 09:42:23AM +0200, Peter Zijlstra wrote: > On Fri, Apr 26, 2019 at 12:45:52AM +0300, Mike Rapoport wrote: > > If a system call runs in isolated context, it's accesses to kernel code and > > data will be verified by SCI susbsytem. > > > > Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > > --- > > arch/x86/mm/fault.c | 28 ++++++++++++++++++++++++++++ > > 1 file changed, 28 insertions(+) > > There's a distinct lack of touching do_double_fault(). It appears to me > that you'll instantly trigger #DF when you #PF, because the #PF handler > itself will not be able to run. The #PF handler is able to run. On interrupt/error entry the cr3 is switched to the full kernel page tables, pretty much like PTI does for user <-> kernel transitions. It's in the patch 3. > And then obviously you have to be very careful to make sure #DF can, > _at_all_times_ run, otherwise you'll tripple-fault and we all know what > that does. > -- Sincerely yours, Mike.
