Re: [Qemu-devel] [Qemu-ppc] [PATCH] pseries: Implements h_read hcall

[David Gibson]

On Fri, Feb 15, 2013 at 08:59:35AM -0200, Erlon Cruz wrote:
> From: Erlon Cruz <address@hidden>
> 
> This h_call is useful for DLPAR in future amongst other things. Given an index
> it fetches the corresponding PTE stored in the htab.
> 
> Signed-off-by: Erlon Cruz <address@hidden>
> ---
>  hw/spapr_hcall.c |   34 ++++++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/hw/spapr_hcall.c b/hw/spapr_hcall.c
> index 2889742..1065277 100644
> --- a/hw/spapr_hcall.c
> +++ b/hw/spapr_hcall.c
> @@ -323,6 +323,39 @@ static target_ulong h_protect(PowerPCCPU *cpu, 
> sPAPREnvironment *spapr,
>      return H_SUCCESS;
>  }
>  
> +static target_ulong h_read(PowerPCCPU *cpu, sPAPREnvironment *spapr,
> +                            target_ulong opcode, target_ulong *args)
> +{
> +    CPUPPCState *env = &cpu->env;
> +    target_ulong flags = args[0];
> +    target_ulong pte_index = args[1];
> +    target_ulong v[4], r[4];
> +    uint8_t *hpte;
> +    int i, ridx, n_entries = 1;
> +
> +    if ((pte_index * HASH_PTE_SIZE_64) & ~env->htab_mask) {
> +        return H_PARAMETER;
> +    }
> +
> +    if (flags & H_READ_4) {
> +        /* Clear the two low order bits */
> +        pte_index &= ~(3ULL);
> +        n_entries = 4;
> +    }
> +
> +    hpte = env->external_htab + (pte_index * HASH_PTE_SIZE_64);
> +
> +    for (i = 0, ridx = 0; i < n_entries; i++) {
> +        v[i] = ldq_p(hpte);
> +        r[i] = ldq_p(hpte + (HASH_PTE_SIZE_64/2));

There's no need for the v and r arrays.  You can just need temporaries
for one entry as you store them one-by-one into args.

Otherwise looks good.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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