Re: [RFC PATCH v8 05/23] target/arm: Support MSR access to ALLINT

[Peter Maydell <peter.maydell@linaro.org>]

On Mon, 18 Mar 2024 at 09:37, Jinjie Ruan <ruanjinjie@huawei.com> wrote:
>
> Support ALLINT msr access as follow:
>         mrs <xt>, ALLINT        // read allint
>         msr ALLINT, <xt>        // write allint with imm
>
> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> ---
> v5:
> - Add Reviewed-by.
> v4:
> - Remove arm_is_el2_enabled() check in allint_check().
> - Change to env->pstate instead of env->allint.
> v3:
> - Remove EL0 check in aa64_allint_access() which alreay checks in .access
>   PL1_RW.
> - Use arm_hcrx_el2_eff() in aa64_allint_access() instead of env->cp15.hcrx_el2.
> - Make ALLINT msr access function controlled by aa64_nmi.
> ---
>  target/arm/helper.c | 34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
>
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index b19a0178ce..aa0151c775 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -4752,6 +4752,36 @@ static void aa64_daif_write(CPUARMState *env, const ARMCPRegInfo *ri,
>      env->daif = value & PSTATE_DAIF;
>  }
>
> +static void aa64_allint_write(CPUARMState *env, const ARMCPRegInfo *ri,
> +                              uint64_t value)
> +{
> +    env->pstate = (env->pstate & ~PSTATE_ALLINT) | (value & PSTATE_ALLINT);
> +}
> +
> +static uint64_t aa64_allint_read(CPUARMState *env, const ARMCPRegInfo *ri)
> +{
> +    return env->pstate & PSTATE_ALLINT;
> +}
> +
> +static CPAccessResult aa64_allint_access(CPUARMState *env,
> +                                         const ARMCPRegInfo *ri, bool isread)
> +{
> +    if (arm_current_el(env) == 1 && (arm_hcrx_el2_eff(env) & HCRX_TALLINT)) {
> +        return CP_ACCESS_TRAP_EL2;
> +    }
> +    return CP_ACCESS_OK;

Forgot to note in my earlier email: HCRX_EL2.TALLINT traps
only writes to ALLINT, not reads, so the condition
here needs to also look at 'isread'.

> +}

thanks
-- PMM