Re: [PATCH v2 7/7] target/arm: Add el_is_in_host

[Peter Maydell]

On Tue, 17 May 2022 at 07:05, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> This (newish) ARM pseudocode function is easier to work with
> than open-coded tests for HCR_E2H etc.  Use of the function
> will be staged into the code base in parts.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/internals.h |  2 ++
>  target/arm/helper.c    | 23 +++++++++++++++++++++++
>  2 files changed, 25 insertions(+)
> +/*
> + * Corresponds to ARM pseudocode function ELIsInHost().
> + */
> +bool el_is_in_host(CPUARMState *env, int el)
> +{
> +    uint64_t mask;
> +    /*
> +     * Since we only care about E2H and TGE, we can skip arm_hcr_el2_eff.
> +     * Perform the simplest bit tests first, and validate EL2 afterward.
> +     */
> +    if (el & 1) {
> +        return false; /* EL1 or EL3 */
> +    }
> +
> +    mask = el ? HCR_E2H : HCR_E2H | HCR_TGE;
> +    if ((env->cp15.hcr_el2 & mask) != mask) {
> +        return false;
> +    }
> +
> +    /* TGE and/or E2H set: double check those bits are currently legal. */
> +    return arm_is_el2_enabled(env) && arm_el_is_aa64(env, 2);
> +}

What about the HaveVirtHostExt() check ?

Otherwise, looks like it matches the pseudocode, but I'd
rather wait until we have some uses of the function before
I think too hard about it.

thanks
-- PMM