Re: [PATCH 2/2] target/arm: Check V7VE as well as LPAE in arm_pamax

[Peter Maydell]

On Sun, 19 Jun 2022 at 01:18, Richard Henderson
<richard.henderson@linaro.org> wrote:
>
> In machvirt_init we create a cpu but do not fully initialize it.
> Thus the propagation of V7VE to LPAE has not been done, and we
> compute the wrong value for some v7 cpus, e.g. cortex-a15.
>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1078
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/ptw.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/target/arm/ptw.c b/target/arm/ptw.c
> index 07f7a21861..da478104f0 100644
> --- a/target/arm/ptw.c
> +++ b/target/arm/ptw.c
> @@ -47,7 +47,13 @@ unsigned int arm_pamax(ARMCPU *cpu)
>          assert(parange < ARRAY_SIZE(pamax_map));
>          return pamax_map[parange];
>      }
> -    if (arm_feature(&cpu->env, ARM_FEATURE_LPAE)) {
> +
> +    /*
> +     * In machvirt_init, we call arm_pamax on a cpu that is not fully
> +     * initialized, so we can't rely on the propagation done in realize.
> +     */
> +    if (arm_feature(&cpu->env, ARM_FEATURE_LPAE) ||
> +        arm_feature(&cpu->env, ARM_FEATURE_V7VE)) {
>          /* v7 with LPAE */
>          return 40;

I guess this is expedient, so on that basis
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>

but as I mentioned in the gitlab issue it's kind of bogus
that the virt board is doing stuff to a non-realized CPU object.

thanks
-- PMM