Re: [PATCH kvmtool v3 7/9] arm64: Make ptrauth enable/disable diagnostics more user-friendly

Dave Martin
2019-06-03T11:14:28Z

On Fri, May 31, 2019 at 06:05:01PM +0100, Andre Przywara wrote:
> On Thu, 30 May 2019 16:13:12 +0100
> Dave Martin <Dave.Martin@arm.com> wrote:
>
> > To help the user understand what is going on, amend ptrauth
> > configuration diagnostic messages to refer to command line options
> > by the exact name used on the command line.
> >
> > Also, provide a clean diagnostic when ptrauth is requested, but not
> > availble. The generic "Unable to initialise vcpu" message is
> > rather cryptic for this case.
>
> Again I don't see much value in having this as a separate patch, as it
> basically just touches code introduced two patches earlier. I think it
> should be merged into 5/9.

Same as with the previous patch, I though it was better to keep it
separate for review purposes for now, since it makes changes on top of
Amit's existing patch.

> > Since we now don't attempt to enable ptrauth at all unless KVM
> > reports the relevant capabilities, remove the error message for
> > that case too: in any case, we can't diagnose precisely why
> > KVM_ARM_VCPU_INIT failed, so the message may be misleading.
>
> So this leaves the only point where we use .enable_ptrauth to that error
> message about the host not supporting it. Not sure if that's worth this
> separate option?

There is indeed a question to be resolved here. See my response to the
penultimate patch.

Cheers
---Dave