Re: [RFC PATCH 5/7] x86/mm/fault: hook up SCI verification

[Peter Zijlstra]

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.

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.