Re: [PATCH v9 10/11] arm: tcg: Adhere to SMCCC 1.3 section 5.2

[Peter Maydell]

On Mon, 13 Sept 2021 at 00:08, Alexander Graf <agraf@csgraf.de> wrote:
>
> The SMCCC 1.3 spec section 5.2 says
>
>   The Unknown SMC Function Identifier is a sign-extended value of (-1)
>   that is returned in the R0, W0 or X0 registers. An implementation must
>   return this error code when it receives:
>
>     * An SMC or HVC call with an unknown Function Identifier
>     * An SMC or HVC call for a removed Function Identifier
>     * An SMC64/HVC64 call from AArch32 state
>
> To comply with these statements, let's always return -1 when we encounter
> an unknown HVC or SMC call.
>
> Signed-off-by: Alexander Graf <agraf@csgraf.de>

Thanks for tracking down the spec requirements.

I agree with the code changes, but the comment at the top of
arm_is_psci_call() also needs to be updated, as it currently
says that we check r0/x0.

-- PMM