Re: [Qemu-devel] [PATCH] target-ppc: Fix htab_mask calculation

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> writes:

> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>
> Correctly update the htab_mask using the return value of
> KVM_PPC_ALLOCATE_HTAB ioctl. Also we don't update sdr1
> on GET_SREGS for HV. So don't update htab_mask if sdr1
> is found to be zero. Fix the pte index calculation to be
> same as that found in the kernel
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr.c          | 3 ++-
>  target-ppc/mmu-hash64.c | 2 +-
>  target-ppc/mmu_helper.c | 4 +++-
>  3 files changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 4a23b6a..4ce069b 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -717,7 +717,8 @@ static void spapr_cpu_reset(void *opaque)
>
>      env->external_htab = (uint8_t *)spapr->htab;
>      env->htab_base = -1;
> -    env->htab_mask = HTAB_SIZE(spapr) - 1;
> +    /* 128 (2**7) bytes in each HPTEG */
> +    env->htab_mask = (1ULL << ((spapr)->htab_shift - 7)) - 1;
>      env->spr[SPR_SDR1] = (target_ulong)(uintptr_t)spapr->htab |
>          (spapr->htab_shift - 18);
>  }
> diff --git a/target-ppc/mmu-hash64.c b/target-ppc/mmu-hash64.c
> index aeb4593..0deeae6 100644
> --- a/target-ppc/mmu-hash64.c
> +++ b/target-ppc/mmu-hash64.c
> @@ -347,7 +347,7 @@ static hwaddr ppc_hash64_pteg_search(CPUPPCState *env, hwaddr hash,
>      unsigned long pte_index;
>      struct ppc_hash64_hpte_token *token;
>
> -    pte_index = (hash * HPTES_PER_GROUP) & env->htab_mask;
> +    pte_index = (hash & env->htab_mask) * HPTES_PER_GROUP;
>      token = ppc_hash64_start_access(ppc_env_get_cpu(env), pte_index);
>      if (!token) {
>          return -1;
> diff --git a/target-ppc/mmu_helper.c b/target-ppc/mmu_helper.c
> index 04a840b..0322304 100644
> --- a/target-ppc/mmu_helper.c
> +++ b/target-ppc/mmu_helper.c
> @@ -2025,7 +2025,9 @@ void ppc_store_sdr1(CPUPPCState *env, target_ulong value)
>                          " stored in SDR1\n", htabsize);
>                  htabsize = 28;
>              }
> -            env->htab_mask = (1ULL << (htabsize + 18)) - 1;
> +            if (htabsize) {
> +                env->htab_mask = (1ULL << (htabsize + 18)) - 1;

This should also be ?

                env->htab_mask = (1ULL << (htabsize + 18 - 7)) - 1;


> +            }
>              env->htab_base = value & SDR_64_HTABORG;
>          } else
>  #endif /* defined(TARGET_PPC64) */

-aneesh