Re: [Qemu-ppc] [PATCH -V8 1/3] target-ppc: Fix htab_mask calculation

[Alexander Graf]

On 23.12.2013, at 18:22, Aneesh Kumar K.V <address@hidden> wrote:

> From: "Aneesh Kumar K.V" <address@hidden>
> 
> 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 <address@hidden>
> ---
> hw/ppc/spapr.c          | 8 +++++++-
> target-ppc/cpu.h        | 1 +
> target-ppc/mmu_helper.c | 4 +++-
> 3 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 267a47d6cc4d..e99a66170661 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -731,7 +731,13 @@ 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;
> +    /*
> +     * htab_mask is the mask used to normalize hash value to PTEG index.
> +     * htab_shift is log2 of hash table size.
> +     * We have 8 hpte per group, and each hpte is 16 bytes.
> +     * ie have 128 bytes per hpte entry.
> +     */
> +    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/cpu.h b/target-ppc/cpu.h
> index 26acdba847fa..82db9a442be5 100644
> --- a/target-ppc/cpu.h
> +++ b/target-ppc/cpu.h
> @@ -955,6 +955,7 @@ struct CPUPPCState {
> #endif
>     /* segment registers */
>     hwaddr htab_base;
> +    /* mask used to normalize hash value to PTEG index */
>     hwaddr htab_mask;
>     target_ulong sr[32];
>     /* externally stored hash table */
> diff --git a/target-ppc/mmu_helper.c b/target-ppc/mmu_helper.c
> index 04a840b01697..c39cb7b89ee0 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) {

Better check for external_htab in the caller and never store SDR1 if we use an 
external htab. If you like, add an assert(!env->external_htab) at the beginning 
of ppc_store_sdr1() to make sure we really never get here.


Alex