Re: [PATCH v6 11/18] target/ppc: Only calculate RMLS derived RMA limit on demand

[David Gibson <david@gibson.dropbear.id.au>]

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On Wed, Feb 26, 2020 at 02:24:53PM +0100, Greg Kurz wrote:
> On Tue, 25 Feb 2020 10:37:17 +1100
> David Gibson <david@gibson.dropbear.id.au> 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.
> > 
> 
> This patch also refactors the code of ppc_hash64_update_vrma(), which
> is definitely an improvement, but seems a bit unrelated to the title...
> I'd personally make it a separate patch but you decide of course :)

Ah, dang it, botched rebase damage.  There are a couple of hunks here
that are supposed to be in the next patch.  I think I've sorted it out
now.

> 
> Also, a cosmetic remark. See below.
> 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > Reviewed-by: Cédric Le Goater <clg@kaod.org>
> > ---
> >  target/ppc/cpu.h        |  1 -
> >  target/ppc/mmu-hash64.c | 84 ++++++++++++++++++++---------------------
> >  2 files changed, 40 insertions(+), 45 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 dd0df6fd01..ac21c14f68 100644
> > --- a/target/ppc/mmu-hash64.c
> > +++ b/target/ppc/mmu-hash64.c
> > @@ -791,6 +791,35 @@ static target_ulong rmls_limit(PowerPCCPU *cpu)
> >      }
> >  }
> >  
> > +static int build_vrma_slbe(PowerPCCPU *cpu, ppc_slb_t *slb)
> > +{
> > +    CPUPPCState *env = &cpu->env;
> > +    target_ulong lpcr = env->spr[SPR_LPCR];
> > +    uint32_t vrmasd = (lpcr & LPCR_VRMASD) >> LPCR_VRMASD_SHIFT;
> > +    target_ulong vsid = SLB_VSID_VRMA | ((vrmasd << 4) & SLB_VSID_LLP_MASK);
> > +    int i;
> > +
> > +    for (i = 0; i < PPC_PAGE_SIZES_MAX_SZ; i++) {
> > +        const PPCHash64SegmentPageSizes *sps = &cpu->hash64_opts->sps[i];
> > +
> > +        if (!sps->page_shift) {
> > +            break;
> > +        }
> > +
> > +        if ((vsid & SLB_VSID_LLP_MASK) == sps->slb_enc) {
> > +            slb->esid = SLB_ESID_V;
> > +            slb->vsid = vsid;
> > +            slb->sps = sps;
> > +            return 0;
> > +        }
> > +    }
> > +
> > +    error_report("Bad page size encoding in LPCR[VRMASD]; LPCR=0x"
> > +                 TARGET_FMT_lx"\n", lpcr);
> > +
> > +    return -1;
> > +}
> > +
> >  int ppc_hash64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr,
> >                                  int rwx, int mmu_idx)
> >  {
> > @@ -844,8 +873,10 @@ 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 {
> > @@ -1007,8 +1038,9 @@ hwaddr ppc_hash64_get_phys_page_debug(PowerPCCPU *cpu, target_ulong addr)
> >                  return -1;
> >              }
> >          } else {
> > +            target_ulong limit = rmls_limit(cpu);
> 
> Maybe add an empty line like you did above for consistency and better
> readability ?

Ok, done.

> 
> Anyway, feel free to add:
> 
> Reviewed-by: Greg Kurz <groug@kaod.org>
> 
> >              /* Emulated old-style RMO mode, bounds check against RMLS */
> > -            if (raddr >= env->rmls) {
> > +            if (raddr >= limit) {
> >                  return -1;
> >              }
> >              return raddr | env->spr[SPR_RMOR];
> > @@ -1043,53 +1075,18 @@ void ppc_hash64_tlb_flush_hpte(PowerPCCPU *cpu, target_ulong ptex,
> >  static void ppc_hash64_update_vrma(PowerPCCPU *cpu)
> >  {
> >      CPUPPCState *env = &cpu->env;
> > -    const PPCHash64SegmentPageSizes *sps = NULL;
> > -    target_ulong esid, vsid, lpcr;
> >      ppc_slb_t *slb = &env->vrma_slb;
> > -    uint32_t vrmasd;
> > -    int i;
> > -
> > -    /* First clear it */
> > -    slb->esid = slb->vsid = 0;
> > -    slb->sps = NULL;
> >  
> >      /* Is VRMA enabled ? */
> > -    if (!ppc_hash64_use_vrma(env)) {
> > -        return;
> > -    }
> > -
> > -    /*
> > -     * Make one up. Mostly ignore the ESID which will not be needed
> > -     * for translation
> > -     */
> > -    lpcr = env->spr[SPR_LPCR];
> > -    vsid = SLB_VSID_VRMA;
> > -    vrmasd = (lpcr & LPCR_VRMASD) >> LPCR_VRMASD_SHIFT;
> > -    vsid |= (vrmasd << 4) & (SLB_VSID_L | SLB_VSID_LP);
> > -    esid = SLB_ESID_V;
> > -
> > -    for (i = 0; i < PPC_PAGE_SIZES_MAX_SZ; i++) {
> > -        const PPCHash64SegmentPageSizes *sps1 = &cpu->hash64_opts->sps[i];
> > -
> > -        if (!sps1->page_shift) {
> > -            break;
> > +    if (ppc_hash64_use_vrma(env)) {
> > +        if (build_vrma_slbe(cpu, slb) == 0) {
> > +            return;
> >          }
> > -
> > -        if ((vsid & SLB_VSID_LLP_MASK) == sps1->slb_enc) {
> > -            sps = sps1;
> > -            break;
> > -        }
> > -    }
> > -
> > -    if (!sps) {
> > -        error_report("Bad page size encoding esid 0x"TARGET_FMT_lx
> > -                     " vsid 0x"TARGET_FMT_lx, esid, vsid);
> > -        return;
> >      }
> >  
> > -    slb->vsid = vsid;
> > -    slb->esid = esid;
> > -    slb->sps = sps;
> > +    /* Otherwise, clear it to indicate error */
> > +    slb->esid = slb->vsid = 0;
> > +    slb->sps = NULL;
> >  }
> >  
> >  void ppc_store_lpcr(PowerPCCPU *cpu, target_ulong val)
> > @@ -1098,7 +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);
> >  }
> >  
> 

-- 
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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