Re: [Qemu-devel] [RFC PATCH 09/17] target/ppc/POWER9: Remove SDR1 register

[David Gibson]

On Fri, Jan 13, 2017 at 05:28:15PM +1100, Suraj Jitindar Singh wrote:
> The SDR1 registers was used to store the location of the hash page table.
> 
> This register no longer exists on POWER9 processors, so don't create it.
> 
> We now store the hash page table location in the process table entry.
> 
> We now check if the SDR1 register exists before printing its value when
> displaying register debug info.
> 
> Signed-off-by: Suraj Jitindar Singh <address@hidden>
> ---
>  target/ppc/kvm.c            | 10 +++++++++-
>  target/ppc/mmu-hash64.c     | 15 ++++++++++++++-
>  target/ppc/translate.c      |  6 ++++--
>  target/ppc/translate_init.c | 16 +++++++++++++---
>  4 files changed, 40 insertions(+), 7 deletions(-)
> 
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 9c4834c..6016930 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -930,7 +930,15 @@ int kvmppc_put_books_sregs(PowerPCCPU *cpu)
>  
>      sregs.pvr = env->spr[SPR_PVR];
>  
> -    sregs.u.s.sdr1 = env->spr[SPR_SDR1];
> +    switch (env->mmu_model) {
> +    case POWERPC_MMU_3_00:
> +        if (env->external_patbe)
> +            sregs.u.s.sdr1 = env->external_patbe->patbe0;

I take it from this that KVM is expecting the address of the guest HPT
in the SDR1 slot of sregs, even on POWER9?  Rather than using a new
ONE_REG entry for the POWER9 data.

Note that this slot was already a hack for PR KVM - we are putting a
userspace address in there, which is clearly not a real SDR1 value.
For HV KVM, I think this value is ignored entirely, since in that case
KVM allocates / controls the guest HPT, not qemu.

> +        break;
> +    default:
> +        sregs.u.s.sdr1 = env->spr[SPR_SDR1];
> +        break;
> +    }

So.. maybe we should take this opportunity to clean this path up and
special case all "external HPT" cases to pass the relevant value to PR
KVM without abusing the env->spr[SPR_SDR1] field.

>  
>      /* Sync SLB */
>  #ifdef TARGET_PPC64
> diff --git a/target/ppc/mmu-hash64.c b/target/ppc/mmu-hash64.c
> index fe7da18..b9d4f4e 100644
> --- a/target/ppc/mmu-hash64.c
> +++ b/target/ppc/mmu-hash64.c
> @@ -291,7 +291,20 @@ void ppc_hash64_set_sdr1(PowerPCCPU *cpu, target_ulong 
> value,
>      CPUPPCState *env = &cpu->env;
>      target_ulong htabsize = value & SDR_64_HTABSIZE;
>  
> -    env->spr[SPR_SDR1] = value;
> +    switch (env->mmu_model) {
> +    case POWERPC_MMU_3_00:
> +        /*
> +         * Technically P9 doesn't have a SDR1, the hash table address should 
> be
> +         * stored in the partition table entry instead.
> +         */
> +        if (env->external_patbe)
> +            env->external_patbe->patbe0 = value;

This definitely doesn't belong in a function called ..._set_sdr1().
Either rename this function or (probably better), set the partition
table entry from a new function and make the decision in the caller.


> +        break;
> +    default:
> +        env->spr[SPR_SDR1] = value;
> +        break;
> +    }
> +
>      if (htabsize > 28) {
>          error_setg(errp,
>                     "Invalid HTABSIZE 0x" TARGET_FMT_lx" stored in SDR1",
> diff --git a/target/ppc/translate.c b/target/ppc/translate.c
> index 1212180..521aed3 100644
> --- a/target/ppc/translate.c
> +++ b/target/ppc/translate.c
> @@ -6922,9 +6922,11 @@ void ppc_cpu_dump_state(CPUState *cs, FILE *f, 
> fprintf_function cpu_fprintf,
>      case POWERPC_MMU_2_06a:
>      case POWERPC_MMU_2_07:
>      case POWERPC_MMU_2_07a:
> +    case POWERPC_MMU_3_00:
>  #endif
> -        cpu_fprintf(f, " SDR1 " TARGET_FMT_lx "   DAR " TARGET_FMT_lx
> -                       "  DSISR " TARGET_FMT_lx "\n", env->spr[SPR_SDR1],
> +        if (env->spr_cb[SPR_SDR1].name)
> +            cpu_fprintf(f, " SDR1 " TARGET_FMT_lx " ", env->spr[SPR_SDR1]);
> +        cpu_fprintf(f, "  DAR " TARGET_FMT_lx "  DSISR " TARGET_FMT_lx "\n",
>                      env->spr[SPR_DAR], env->spr[SPR_DSISR]);
>          break;
>      case POWERPC_MMU_BOOKE206:
> diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
> index a1994d3..c771ba3 100644
> --- a/target/ppc/translate_init.c
> +++ b/target/ppc/translate_init.c
> @@ -32,6 +32,7 @@
>  #include "qapi/visitor.h"
>  #include "hw/qdev-properties.h"
>  #include "hw/ppc/ppc.h"
> +#include "mmu.h"
>  
>  //#define PPC_DUMP_CPU
>  //#define PPC_DEBUG_SPR
> @@ -722,8 +723,8 @@ static void gen_spr_generic (CPUPPCState *env)
>                   0x00000000);
>  }
>  
> -/* SPR common to all non-embedded PowerPC, including 601 */
> -static void gen_spr_ne_601 (CPUPPCState *env)
> +/* SPR common to all non-embedded PowerPC, including POWER9 */
> +static void gen_spr_ne_power9 (CPUPPCState *env)
>  {
>      /* Exception processing */
>      spr_register_kvm(env, SPR_DSISR, "DSISR",
> @@ -739,6 +740,12 @@ static void gen_spr_ne_601 (CPUPPCState *env)
>                   SPR_NOACCESS, SPR_NOACCESS,
>                   &spr_read_decr, &spr_write_decr,
>                   0x00000000);
> +}
> +
> +/* SPR common to all non-embedded PowerPC, including 601 */
> +static void gen_spr_ne_601 (CPUPPCState *env)
> +{
> +    gen_spr_ne_power9(env);
>      /* Memory management */
>      spr_register(env, SPR_SDR1, "SDR1",
>                   SPR_NOACCESS, SPR_NOACCESS,
> @@ -8222,7 +8229,6 @@ static void gen_spr_power8_rpr(CPUPPCState *env)
>  
>  static void init_proc_book3s_64(CPUPPCState *env, int version)
>  {
> -    gen_spr_ne_601(env);
>      gen_tbl(env);
>      gen_spr_book3s_altivec(env);
>      gen_spr_book3s_pmu_sup(env);
> @@ -8280,6 +8286,10 @@ static void init_proc_book3s_64(CPUPPCState *env, int 
> version)
>          gen_spr_power8_book4(env);
>          gen_spr_power8_rpr(env);
>      }
> +    if (version >= BOOK3S_CPU_POWER9)
> +        gen_spr_ne_power9(env);
> +    else
> +        gen_spr_ne_601(env);
>      if (version < BOOK3S_CPU_POWER8) {
>          gen_spr_book3s_dbg(env);
>      } else {

-- 
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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