Re: [Qemu-devel] [RFC PATCH 08/17] target/ppc/POWER9: Add external partition table pointer to cpu state

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

On Wed, 2017-02-01 at 15:09 +1100, David Gibson wrote:
> On Fri, Jan 13, 2017 at 05:28:14PM +1100, Suraj Jitindar Singh wrote:
> > 
> > Similarly to how we have an external hpt pointer in the cpu state,
> > add
> > an external partition table pointer and update it to point to the
> > partition table entry in the machine state struct on cpu reset.
> > 
> > Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> As with the previous patch, I don't quite follow what's going on
> here.  It seems to me that if the external HPT is set, that should
> make the softmmu logic bypass *both* an HPT set by SDR1 (<= POWER8)
> or
> an HPT set by the partition table (POWER9).  So I'm not sure why we
> need the dummy partition table entry.
> 
> To look at it another way, the external HPT is special because it
> lies
> outside the guest's address space, but we need its state because the
> guest can manipulate it via hypercall.  For the partition table
> entry,
> even if we're minimally modelling the HV parts of the POWER9 MMU,
> isn't the partition table entry just fixed at startup?
Similarly this patch will be dropped from the series.
> 
> > 
> > ---
> >  hw/ppc/spapr_cpu_core.c | 12 ++++++++++--
> >  target/ppc/cpu.h        |  3 +++
> >  target/ppc/mmu.h        |  6 ++++++
> >  target/ppc/mmu_helper.c | 12 ++++++++++++
> >  4 files changed, 31 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> > index 8cc7058..72a7f90 100644
> > --- a/hw/ppc/spapr_cpu_core.c
> > +++ b/hw/ppc/spapr_cpu_core.c
> > @@ -17,6 +17,7 @@
> >  #include "hw/ppc/ppc.h"
> >  #include "target/ppc/mmu-hash64.h"
> >  #include "sysemu/numa.h"
> > +#include "mmu.h"
> >  
> >  static void spapr_cpu_reset(void *opaque)
> >  {
> > @@ -34,8 +35,15 @@ static void spapr_cpu_reset(void *opaque)
> >  
> >      env->spr[SPR_HIOR] = 0;
> >  
> > -    ppc_hash64_set_external_hpt(cpu, spapr->htab, spapr-
> > >htab_shift,
> > -                                &error_fatal);
> > +    switch (env->mmu_model) {
> > +    case POWERPC_MMU_3_00:
> > +        ppc64_set_external_patb(cpu, spapr->patb, &error_fatal);
> > +    default:
> > +        /* We assume legacy until told otherwise, thus set HPT
> > irrespective */
> > +        ppc_hash64_set_external_hpt(cpu, spapr->htab, spapr-
> > >htab_shift,
> > +                                    &error_fatal);
> > +        break;
> > +    }
> >  }
> >  
> >  static void spapr_cpu_destroy(PowerPCCPU *cpu)
> > diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> > index 0ab49b3..e8b7c06 100644
> > --- a/target/ppc/cpu.h
> > +++ b/target/ppc/cpu.h
> > @@ -77,6 +77,7 @@
> >  #include "exec/cpu-defs.h"
> >  #include "cpu-qom.h"
> >  #include "fpu/softfloat.h"
> > +#include "mmu.h"
> >  
> >  #if defined (TARGET_PPC64)
> >  #define PPC_ELF_MACHINE     EM_PPC64
> > @@ -1009,6 +1010,8 @@ struct CPUPPCState {
> >      target_ulong sr[32];
> >      /* externally stored hash table */
> >      uint8_t *external_htab;
> > +    /* externally stored partition table entry */
> > +    struct patb_entry *external_patbe;
> >      /* BATs */
> >      uint32_t nb_BATs;
> >      target_ulong DBAT[2][8];
> > diff --git a/target/ppc/mmu.h b/target/ppc/mmu.h
> > index 67b9707..c7967c3 100644
> > --- a/target/ppc/mmu.h
> > +++ b/target/ppc/mmu.h
> > @@ -8,6 +8,12 @@ struct patb_entry {
> >      uint64_t patbe0, patbe1;
> >  };
> >  
> > +#ifdef TARGET_PPC64
> > +
> > +void ppc64_set_external_patb(PowerPCCPU *cpu, void *patb, Error
> > **errp);
> > +
> > +#endif /* TARGET_PPC64 */
> > +
> >  #endif /* CONFIG_USER_ONLY */
> >  
> >  #endif /* MMU_H */
> > diff --git a/target/ppc/mmu_helper.c b/target/ppc/mmu_helper.c
> > index 2ab4562..bc6c117 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 "mmu.h"
> >  
> >  //#define DEBUG_MMU
> >  //#define DEBUG_BATS
> > @@ -2907,3 +2908,14 @@ void tlb_fill(CPUState *cs, target_ulong
> > addr, MMUAccessType access_type,
> >                                 retaddr);
> >      }
> >  }
> > +
> > +/*****************************************************************
> > *************/
> > +
> > +/* ISA v3.00 (POWER9) Generic MMU Helpers */
> > +
> > +void ppc64_set_external_patb(PowerPCCPU *cpu, void *patb, Error
> > **errp)
> > +{
> > +    CPUPPCState *env = &cpu->env;
> > +
> > +    env->external_patbe = (struct patb_entry *) patb;
> > +}