Re: [PATCH v6 02/14] target/arm: Add ptw_idx to S1Translate

["Alex Bennée" <alex.bennee@linaro.org>]

Richard Henderson <richard.henderson@linaro.org> writes:

> Hoist the computation of the mmu_idx for the ptw up to
> get_phys_addr_with_struct and get_phys_addr_twostage.
> This removes the duplicate check for stage2 disabled
> from the middle of the walk, performing it only once.
>
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  target/arm/ptw.c | 71 ++++++++++++++++++++++++++++++++++++------------
>  1 file changed, 54 insertions(+), 17 deletions(-)
>
> diff --git a/target/arm/ptw.c b/target/arm/ptw.c
> index 004375e02b..161b7922e3 100644
> --- a/target/arm/ptw.c
> +++ b/target/arm/ptw.c
> @@ -17,6 +17,7 @@
>  
>  typedef struct S1Translate {
>      ARMMMUIdx in_mmu_idx;
> +    ARMMMUIdx in_ptw_idx;

I could use a comment here to explain the difference between mmu and ptr
indexes here because...

<snip>
> @@ -2527,10 +2536,32 @@ static bool get_phys_addr_with_struct(CPUARMState *env, S1Translate *ptw,
>                                        ARMMMUFaultInfo *fi)
>  {
>      ARMMMUIdx mmu_idx = ptw->in_mmu_idx;
> -    ARMMMUIdx s1_mmu_idx = stage_1_mmu_idx(mmu_idx);
>      bool is_secure = ptw->in_secure;
> +    ARMMMUIdx s1_mmu_idx;
>  
> -    if (mmu_idx != s1_mmu_idx) {
> +    switch (mmu_idx) {
> +    case ARMMMUIdx_Phys_S:
> +    case ARMMMUIdx_Phys_NS:
> +        /* Checking Phys early avoids special casing later vs regime_el. */
> +        return get_phys_addr_disabled(env, address, access_type, mmu_idx,
> +                                      is_secure, result, fi);
> +
> +    case ARMMMUIdx_Stage1_E0:
> +    case ARMMMUIdx_Stage1_E1:
> +    case ARMMMUIdx_Stage1_E1_PAN:
> +        /* First stage lookup uses second stage for ptw. */
> +        ptw->in_ptw_idx = is_secure ? ARMMMUIdx_Stage2_S : ARMMMUIdx_Stage2;
> +        break;
> +
> +    case ARMMMUIdx_E10_0:
> +        s1_mmu_idx = ARMMMUIdx_Stage1_E0;
> +        goto do_twostage;
> +    case ARMMMUIdx_E10_1:
> +        s1_mmu_idx = ARMMMUIdx_Stage1_E1;
> +        goto do_twostage;
> +    case ARMMMUIdx_E10_1_PAN:
> +        s1_mmu_idx = ARMMMUIdx_Stage1_E1_PAN;
> +    do_twostage:
>          /*
>           * Call ourselves recursively to do the stage 1 and then stage 2
>           * translations if mmu_idx is a two-stage regime, and EL2 present.
> @@ -2541,6 +2572,12 @@ static bool get_phys_addr_with_struct(CPUARMState *env, S1Translate *ptw,
>              return get_phys_addr_twostage(env, ptw, address, access_type,
>                                            result, fi);
>          }
> +        /* fall through */

following this I got confused as to what might be overwritten or
ignored. I assume for v8-A (ARM_FEATURE_EL2) we won't be falling through
anyway?

Anyway I think I understand it now:

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>


> +
> +    default:
> +        /* Single stage and second stage uses physical for ptw. */
> +        ptw->in_ptw_idx = is_secure ? ARMMMUIdx_Phys_S : ARMMMUIdx_Phys_NS;
> +        break;
>      }
>  
>      /*


-- 
Alex Bennée