Re: [PATCH v6 04/13] arm64/kvm: hide ptrauth from guests

From: Marc Zyngier
Date: Sat Dec 08 2018 - 05:32:52 EST

On Fri, 07 Dec 2018 18:39:22 +0000,
Kristina Martsenko <kristina.martsenko@xxxxxxx> wrote:
> From: Mark Rutland <mark.rutland@xxxxxxx>
> In subsequent patches we're going to expose ptrauth to the host kernel
> and userspace, but things are a bit trickier for guest kernels. For the
> time being, let's hide ptrauth from KVM guests.
> Regardless of how well-behaved the guest kernel is, guest userspace
> could attempt to use ptrauth instructions, triggering a trap to EL2,
> resulting in noise from kvm_handle_unknown_ec(). So let's write up a
> handler for the PAC trap, which silently injects an UNDEF into the
> guest, as if the feature were really missing.
> Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx>
> Signed-off-by: Kristina Martsenko <kristina.martsenko@xxxxxxx>
> Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
> Reviewed-by: Christoffer Dall <christoffer.dall@xxxxxxx>
> Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
> Cc: kvmarm@xxxxxxxxxxxxxxxxxxxxx

Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx>


Jazz is not dead, it just smell funny.