Re: [PATCH v2 06/23] target/arm: Make HSTR_EL2 traps take priority over UNDEF-at-EL1

[Richard Henderson <richard.henderson@linaro.org>]

On 1/30/23 08:24, Peter Maydell wrote:
> The semantics of HSTR_EL2 require that it traps cpreg accesses
> to EL2 for:
>   * EL1 accesses
>   * EL0 accesses, if the access is not UNDEFINED when the
>     trap bit is 0
> 
> (You can see this in the I_ZFGJP priority ordering, where HSTR_EL2
> traps from EL1 to EL2 are priority 12, UNDEFs are priority 13, and
> HSTR_EL2 traps from EL0 are priority 15.)
> 
> However, we don't get this right for EL1 accesses which UNDEF because
> the register doesn't exist at all or because its ri->access bits
> non-configurably forbid the access.  At EL1, check for the HSTR_EL2
> trap early, before either of these UNDEF reasons.
> 
> We have to retain the HSTR_EL2 check in access_check_cp_reg(),
> because at EL0 any kind of UNDEF-to-EL1 (including "no such
> register", "bad ri->access" and "ri->accessfn returns 'trap to EL1'")
> takes precedence over the trap to EL2.  But we only need to do that
> check for EL0 now.
> 
> Signed-off-by: Peter Maydell<peter.maydell@linaro.org>
> Message-id:20230127175507.2895013-7-peter.maydell@linaro.org
> ---
>   target/arm/op_helper.c |  6 +++++-
>   target/arm/translate.c | 28 +++++++++++++++++++++++++++-
>   2 files changed, 32 insertions(+), 2 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~