Re: [PATCH 1/3] target/arm: keep translation start level unsigned

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

On 12/18/20 6:33 AM, remi.denis.courmont@huawei.com wrote:
> From: Rémi Denis-Courmont <remi.denis.courmont@huawei.com>
> 
> Signed-off-by: Rémi Denis-Courmont <remi.denis.courmont@huawei.com>
> ---
>  target/arm/helper.c | 14 ++++++--------
>  1 file changed, 6 insertions(+), 8 deletions(-)

The patch does more than what is described above.

> 
> diff --git a/target/arm/helper.c b/target/arm/helper.c
> index df195c314c..b927e53ab0 100644
> --- a/target/arm/helper.c
> +++ b/target/arm/helper.c
> @@ -10821,17 +10821,12 @@ do_fault:
>   * Returns true if the suggested S2 translation parameters are OK and
>   * false otherwise.
>   */
> -static bool check_s2_mmu_setup(ARMCPU *cpu, bool is_aa64, int level,
> +static bool check_s2_mmu_setup(ARMCPU *cpu, bool is_aa64, uint32_t level,
>                                 int inputsize, int stride)
>  {
>      const int grainsize = stride + 3;
>      int startsizecheck;
>  
> -    /* Negative levels are never allowed.  */
> -    if (level < 0) {
> -        return false;
> -    }
> -

I would expect this to be the only hunk from the patch description.  Probably
changing this negative check to a >= 3 check.


r~

>      startsizecheck = inputsize - ((3 - level) * stride + grainsize);
>      if (startsizecheck < 1 || startsizecheck > stride + 4) {
>          return false;
> @@ -10856,6 +10851,9 @@ static bool check_s2_mmu_setup(ARMCPU *cpu, bool is_aa64, int level,
>              if (level == 0 && pamax <= 42) {
>                  return false;
>              }
> +            if (level == 3) {
> +                return false;
> +            }
>              break;
>          default:
>              g_assert_not_reached();
> @@ -10871,7 +10869,7 @@ static bool check_s2_mmu_setup(ARMCPU *cpu, bool is_aa64, int level,
>          /* AArch32 only supports 4KB pages. Assert on that.  */
>          assert(stride == 9);
>  
> -        if (level == 0) {
> +        if (level == 0 || level >= 3) {
>              return false;
>          }
>      }
> @@ -11203,7 +11201,7 @@ static bool get_phys_addr_lpae(CPUARMState *env, uint64_t address,
>  
>          if (!aarch64 || stride == 9) {
>              /* AArch32 or 4KB pages */
> -            startlevel = 2 - sl0;
> +            startlevel = (2 - sl0) & 3;
>          } else {
>              /* 16KB or 64KB pages */
>              startlevel = 3 - sl0;
>