Re: [PATCH v2 33/39] x86/cpufeatures: Limit shadow stack to Intel CPUs

From: Kees Cook
Date: Tue Oct 04 2022 - 00:54:39 EST

On Mon, Oct 03, 2022 at 05:09:04PM -0700, Dave Hansen wrote:
> On 10/3/22 16:57, Kees Cook wrote:
> > On Thu, Sep 29, 2022 at 03:29:30PM -0700, Rick Edgecombe wrote:
> >> Shadow stack is supported on newer AMD processors, but the kernel
> >> implementation has not been tested on them. Prevent basic issues from
> >> showing up for normal users by disabling shadow stack on all CPUs except
> >> Intel until it has been tested. At which point the limitation should be
> >> removed.
> >>
> >> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@xxxxxxxxx>
> > So running the selftests on an AMD system is sufficient to drop this
> > patch?
> Yes, that's enough.
> I _thought_ the AMD folks provided some tested-by's at some point in the
> past. But, maybe I'm confusing this for one of the other shared
> features. Either way, I'm sure no tested-by's were dropped on purpose.
> I'm sure Rick is eager to trim down his series and this would be a great
> patch to drop. Does anyone want to make that easy for Rick?
> <hint> <hint>

Hey Gustavo, Nathan, or Nick! I know y'all have some fancy AMD testing
rigs. Got a moment to spin up this series and run the selftests? :)

Kees Cook