Re: [Xen-devel] [RFC] WIP: optee: add OP-TEE mediator

[Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>]

Hi Stefano,


On 05.12.17 00:06, Stefano Stabellini wrote:
> On Mon, 4 Dec 2017, Volodymyr Babchuk wrote:
> > > = Xen command forwarding =
> > >
> > > In the code below, it looks like Xen is forwarding everything to OP-TEE.
> > > Are there some commands Xen should avoid forwarding? Should we have a
> > > whitelist or a blacklist?
> > My code implements whitelists (at least, I hope so :-) ). It forwards
> > only known requests. If it does not know type of the request, it
> > returns error back to a caller.
> Actually, see below:
>
>
> > > > +static bool optee_handle_smc(struct cpu_user_regs *regs)
> > > > +{
> > > > +
> > > > +    switch ( get_user_reg(regs, 0) )
> > > > +    {
> > > > +    case OPTEE_SMC_GET_SHM_CONFIG:
> > > > +        return handle_get_shm_config(regs);
> > > > +    case OPTEE_SMC_EXCHANGE_CAPABILITIES:
> > > > +        return handle_exchange_capabilities(regs);
> > > > +    case OPTEE_SMC_CALL_WITH_ARG:
> > > > +        return handle_std_call(regs);
> > > > +    case OPTEE_SMC_CALL_RETURN_FROM_RPC:
> > > > +        return handle_rpc(regs);
> > > > +    default:
> > > > +        return forward_call(regs);
> > > > +    }
> > > > +    return false;
> > > > +}
> In the unknown ("default") case the smc is still forwarded. Am I missing
> anything?
No, you are right. It is I who missed to complete this piece of code. 
There should be a list of all known OPTEE_SMC_* commands, plus "return 
false" in "default" case.
WBR,
--
Volodymyr Babchuk

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