Re: [PATCH 1/2] target/arm: Add cpu property to control pauth

[Mark Rutland]

On Thu, Aug 13, 2020 at 08:03:21AM +0200, Andrew Jones wrote:
> Thinking about this some more, maybe we don't need pauth-arch.
> If we don't, then it simplifies nicely to
> 
>  # Default (enabled with architected algorithm)
>  -cpu max[,pauth=on][,pauth-fast=off]
> 
>  # Select pauth-fast
>  -cpu max[,pauth=on],pauth-fast=on

One reason that users may wish to choose the IMP-DEF algorithm is for
functional testing regardless of speed (since APA+GPA / API+GPI depend
on whether the algo is architected or imp-def).

Given that, I think that "impdef" is a better option name than
"pauth-fast", and speed is a benefit but not the only reason to use the
option.

How about hacing a 'pauth-algo' option which defaults to architected,
e.g.

| -cpu max,pauth={on,off},pauth-algo={impdef,architected}

... then in future the 'pauth={on,off}' bit could de extended to cover
FPAC version etc independently of the algorithm, but for now that can be
a boolean.

Thanks,
Mark.