Re: [Qemu-devel] [RFC PATCH 10/17] target/ppc/POWER9: Add POWER9 mmu fault handler

[Suraj Jitindar Singh <sjitindarsingh@gmail.com>]

On Wed, 2017-02-01 at 15:23 +1100, David Gibson wrote:
> On Fri, Jan 13, 2017 at 05:28:16PM +1100, Suraj Jitindar Singh wrote:
> > 
> > Add a new mmu fault handler for the POWER9 cpu and add it as the
> > handler
> > for the POWER9 cpu definition.
> > 
> > This handler checks if the guest is radix or hash based on the
> > value in the
> > partition table entry and calls the correct fault handler
> > accordingly.
> > 
> > The hash fault handling code has also been updated to check if the
> > partition is using segment tables.
> > 
> > Currently only legacy hash (no segment tables) is supported.
> > 
> > Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> > ---
> >  target/ppc/mmu-hash64.c     |  8 ++++++++
> >  target/ppc/mmu.h            |  8 ++++++++
> >  target/ppc/mmu_helper.c     | 47
> > +++++++++++++++++++++++++++++++++++++++++++++
> >  target/ppc/translate_init.c |  2 +-
> >  4 files changed, 64 insertions(+), 1 deletion(-)
> > 
> > diff --git a/target/ppc/mmu-hash64.c b/target/ppc/mmu-hash64.c
> > index b9d4f4e..b476b3f 100644
> > --- a/target/ppc/mmu-hash64.c
> > +++ b/target/ppc/mmu-hash64.c
> > @@ -73,6 +73,14 @@ static ppc_slb_t *slb_lookup(PowerPCCPU *cpu,
> > target_ulong eaddr)
> >          }
> >      }
> >  
> > +    /* Check if in-memory segment tables are in use */
> > +    if (ppc64_use_proc_tbl(cpu)) {
> > +        /* TODO - Unsupported */
> > +        qemu_log_mask(LOG_UNIMP, "%s: unimplemented - segment
> > table support\n",
> > +                      __func__);
> > +        /* Not much we can do here, caller will generate a segment
> > interrupt */
> > +    }
> I think this logic would be better in the fault handler.  For the
> fault path in the segment table case, I don't think we want to even
> model the SLB (in hardware the SLB is an important optimization, but
> I
> don't think the software SLB will be notably better than just looking
> up the seg table directly).  I think the other users of slb_lookup()
> are in contexts that only make sense in the context of a software
> managed SLB anyway.
> 
The mmu looks up the slb before it looks in the segment tables, so we
still need to model and search the slb before we search segment tables.
We could call slb lookup and if that fails we can then call a
search_seg_tbl() or something from the fault handler.
> > 
> >      return NULL;
> >  }
> >  
> > diff --git a/target/ppc/mmu.h b/target/ppc/mmu.h
> > index c7967c3..e07b128 100644
> > --- a/target/ppc/mmu.h
> > +++ b/target/ppc/mmu.h
> > @@ -3,6 +3,10 @@
> >  
> >  #ifndef CONFIG_USER_ONLY
> >  
> > +/* Common Partition Table Entry Fields */
> > +#define PATBE0_HR                0x8000000000000000
> > +#define PATBE1_GR                0x8000000000000000
> > +
> >  /* Partition Table Entry */
> >  struct patb_entry {
> >      uint64_t patbe0, patbe1;
> > @@ -11,6 +15,10 @@ struct patb_entry {
> >  #ifdef TARGET_PPC64
> >  
> >  void ppc64_set_external_patb(PowerPCCPU *cpu, void *patb, Error
> > **errp);
> > +bool ppc64_use_proc_tbl(PowerPCCPU *cpu);
> > +bool ppc64_radix_guest(PowerPCCPU *cpu);
> > +int ppc64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr, int rwx,
> > +                           int mmu_idx);
> >  
> >  #endif /* TARGET_PPC64 */
> >  
> > diff --git a/target/ppc/mmu_helper.c b/target/ppc/mmu_helper.c
> > index bc6c117..612f407 100644
> > --- a/target/ppc/mmu_helper.c
> > +++ b/target/ppc/mmu_helper.c
> > @@ -28,6 +28,7 @@
> >  #include "exec/cpu_ldst.h"
> >  #include "exec/log.h"
> >  #include "helper_regs.h"
> > +#include "qemu/error-report.h"
> >  #include "mmu.h"
> >  
> >  //#define DEBUG_MMU
> > @@ -1281,6 +1282,17 @@ void dump_mmu(FILE *f, fprintf_function
> > cpu_fprintf, CPUPPCState *env)
> >      case POWERPC_MMU_2_07a:
> >          dump_slb(f, cpu_fprintf, ppc_env_get_cpu(env));
> >          break;
> > +    case POWERPC_MMU_3_00:
> > +        if (ppc64_radix_guest(ppc_env_get_cpu(env))) {
> > +            /* TODO - Unsupported */
> > +        } else {
> > +            if (ppc64_use_proc_tbl(ppc_env_get_cpu(env))) {
> > +                /* TODO - Unsupported */
> > +            } else {
> > +                dump_slb(f, cpu_fprintf, ppc_env_get_cpu(env));
> > +                break;
> > +            }
> > +        }
> >  #endif
> >      default:
> >          qemu_log_mask(LOG_UNIMP, "%s: unimplemented\n", __func__);
> > @@ -1422,6 +1434,17 @@ hwaddr ppc_cpu_get_phys_page_debug(CPUState
> > *cs, vaddr addr)
> >      case POWERPC_MMU_2_07:
> >      case POWERPC_MMU_2_07a:
> >          return ppc_hash64_get_phys_page_debug(cpu, addr);
> > +    case POWERPC_MMU_3_00:
> > +        if (ppc64_radix_guest(ppc_env_get_cpu(env))) {
> > +            /* TODO - Unsupported */
> > +        } else {
> > +            if (ppc64_use_proc_tbl(ppc_env_get_cpu(env))) {
> > +                /* TODO - Unsupported */
> > +            } else {
> > +                return ppc_hash64_get_phys_page_debug(cpu, addr);
> > +            }
> > +        }
> > +        break;
> >  #endif
> >  
> >      case POWERPC_MMU_32B:
> > @@ -2919,3 +2942,27 @@ void ppc64_set_external_patb(PowerPCCPU
> > *cpu, void *patb, Error **errp)
> >  
> >      env->external_patbe = (struct patb_entry *) patb;
> >  }
> > +
> > +inline bool ppc64_use_proc_tbl(PowerPCCPU *cpu)
> There's basically no point putting an inline on functions that are in
> a .c rather than a .h (it will only be inlined for callers in this
> .o,
> not elsewhere).  These are simple enough that I think they do belong
> in the .h instead.
I'll move these into the .h
> 
> > 
> > +{
> > +    return !!(cpu->env.spr[SPR_LPCR] & LPCR_UPRT);
> > +}
> > +
> > +inline bool ppc64_radix_guest(PowerPCCPU *cpu)
> > +{
> > +    struct patb_entry *patbe = cpu->env.external_patbe;
> > +
> > +    return patbe && (patbe->patbe1 & PATBE1_GR);
> > +}
> > +
> > +int ppc64_handle_mmu_fault(PowerPCCPU *cpu, vaddr eaddr, int rwx,
> > +                           int mmu_idx)
> I think this name is too generic, since it's really only right for
> POWER9 / MMU v3.
Ok, how about ppc64_v3_handle_mmu_fault?
> 
> > 
> > +{
> > +    if (ppc64_radix_guest(cpu)) { /* Guest uses radix */
> > +        /* TODO - Unsupported */
> > +        error_report("Guest Radix Support Unimplemented\n");
> > +        abort();
> > +    } else { /* Guest uses hash */
> > +        return ppc_hash64_handle_mmu_fault(cpu, eaddr, rwx,
> > mmu_idx);
> > +    }
> > +}
> > diff --git a/target/ppc/translate_init.c
> > b/target/ppc/translate_init.c
> > index c771ba3..87297a7 100644
> > --- a/target/ppc/translate_init.c
> > +++ b/target/ppc/translate_init.c
> > @@ -8850,7 +8850,7 @@ POWERPC_FAMILY(POWER9)(ObjectClass *oc, void
> > *data)
> >                      (1ull << MSR_LE);
> >      pcc->mmu_model = POWERPC_MMU_3_00;
> >  #if defined(CONFIG_SOFTMMU)
> > -    pcc->handle_mmu_fault = ppc_hash64_handle_mmu_fault;
> > +    pcc->handle_mmu_fault = ppc64_handle_mmu_fault;
> >      /* segment page size remain the same */
> >      pcc->sps = &POWER7_POWER8_sps;
> >  #endif