Re: [PATCH 4/6] target/riscv: Detect sxl to set bit width for RV32 in RV64

[Alistair Francis]

On Mon, Jul 1, 2024 at 1:41 PM LIU Zhiwei <zhiwei_liu@linux.alibaba.com> wrote:
>
> From: TANG Tiancheng <tangtiancheng.ttc@alibaba-inc.com>
>
> Ensure correct bit width based on sxl when running RV32 on RV64 QEMU.
> This is required as MMU address translations run in S-mode.
>
> Signed-off-by: TANG Tiancheng <tangtiancheng.ttc@alibaba-inc.com>
> Reviewed-by: Liu Zhiwei <zhiwei_liu@linux.alibaba.com>
> ---
>  target/riscv/cpu_helper.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index 6709622dd3..1af83a0a36 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -887,12 +887,14 @@ static int get_physical_address(CPURISCVState *env, 
> hwaddr *physical,
>
>      CPUState *cs = env_cpu(env);
>      int va_bits = PGSHIFT + levels * ptidxbits + widened;
> +    int sxlen = 16UL << riscv_cpu_sxl(env);
> +    int sxlen_bytes = sxlen / 8;
>
>      if (first_stage == true) {
>          target_ulong mask, masked_msbs;
>
> -        if (TARGET_LONG_BITS > (va_bits - 1)) {
> -            mask = (1L << (TARGET_LONG_BITS - (va_bits - 1))) - 1;
> +        if (sxlen > (va_bits - 1)) {
> +            mask = (1L << (sxlen - (va_bits - 1))) - 1;
>          } else {
>              mask = 0;
>          }
> @@ -961,7 +963,7 @@ restart:
>
>          int pmp_prot;
>          int pmp_ret = get_physical_address_pmp(env, &pmp_prot, pte_addr,
> -                                               sizeof(target_ulong),
> +                                               sxlen_bytes,
>                                                 MMU_DATA_LOAD, PRV_S);
>          if (pmp_ret != TRANSLATE_SUCCESS) {
>              return TRANSLATE_PMP_FAIL;
> @@ -1113,7 +1115,7 @@ restart:
>           *   it is no longer valid and we must re-walk the page table.
>           */
>          MemoryRegion *mr;
> -        hwaddr l = sizeof(target_ulong), addr1;
> +        hwaddr l = sxlen_bytes, addr1;
>          mr = address_space_translate(cs->as, pte_addr, &addr1, &l,
>                                       false, MEMTXATTRS_UNSPECIFIED);
>          if (memory_region_is_ram(mr)) {
> @@ -1126,6 +1128,11 @@ restart:
>              *pte_pa = pte = updated_pte;
>  #else
>              target_ulong old_pte = qatomic_cmpxchg(pte_pa, pte, updated_pte);

I think you missed removing this line

Alistair

> +            if (riscv_cpu_sxl(env) == MXL_RV32) {
> +                old_pte = qatomic_cmpxchg((uint32_t *)pte_pa, pte, 
> updated_pte);
> +            } else {
> +                old_pte = qatomic_cmpxchg(pte_pa, pte, updated_pte);
> +            }
>              if (old_pte != pte) {
>                  goto restart;
>              }
> --
> 2.43.0
>
>