Re: [PATCH v7 10/17] target/ppc: Only calculate RMLS derived RMA limit on demand

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 3/3/20 4:43 AM, David Gibson wrote:
> When the LPCR is written, we update the env->rmls field with the RMA limit
> it implies.  Simplify things by just calculating the value directly from
> the LPCR value when we need it.
> 
> It's possible this is a little slower, but it's unlikely to be significant,
> since this is only for real mode accesses in a translation configuration
> that's not used very often, and the whole thing is behind the qemu TLB
> anyway.  Therefore, keeping the number of state variables down and not
> having to worry about making sure it's always in sync seems the better
> option.
> 
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>   target/ppc/cpu.h        | 1 -
>   target/ppc/mmu-hash64.c | 9 ++++++---
>   2 files changed, 6 insertions(+), 4 deletions(-)
> 
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 8077fdb068..f9871b1233 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -1046,7 +1046,6 @@ struct CPUPPCState {
>       uint64_t insns_flags2;
>   #if defined(TARGET_PPC64)
>       ppc_slb_t vrma_slb;
> -    target_ulong rmls;
>   #endif
>   
>       int error_code;
> diff --git a/target/ppc/mmu-hash64.c b/target/ppc/mmu-hash64.c
> index fcccaabb88..4fd7b7ee74 100644
> --- a/target/ppc/mmu-hash64.c
> +++ b/target/ppc/mmu-hash64.c
> @@ -837,8 +837,10 @@ int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr,
>   
>               goto skip_slb_search;
>           } else {
> +            target_ulong limit = rmls_limit(cpu);
> +
>               /* Emulated old-style RMO mode, bounds check against RMLS */
> -            if (raddr >= env->rmls) {
> +            if (raddr >= limit) {
>                   if (rwx == 2) {
>                       ppc_hash64_set_isi(cs, SRR1_PROTFAULT);
>                   } else {
> @@ -1000,8 +1002,10 @@ hwaddr ppc_hash64_get_phys_page_debug(PowerPCCPU *cpu, target_ulong addr)
>                   return -1;
>               }
>           } else {
> +            target_ulong limit = rmls_limit(cpu);
> +
>               /* Emulated old-style RMO mode, bounds check against RMLS */
> -            if (raddr >= env->rmls) {
> +            if (raddr >= limit) {
>                   return -1;
>               }
>               return raddr | env->spr[SPR_RMOR];
> @@ -1091,7 +1095,6 @@ void ppc_store_lpcr(PowerPCCPU *cpu, target_ulong val)
>       CPUPPCState *env = &cpu->env;
>   
>       env->spr[SPR_LPCR] = val & pcc->lpcr_mask;
> -    env->rmls = rmls_limit(cpu);
>       ppc_hash64_update_vrma(cpu);
>   }
>   
> 

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>