Re: [Qemu-devel] [RFC 07/17] ppc: Rewrite ppc_set_compat()

[Alexey Kardashevskiy]

On 30/10/16 22:11, David Gibson wrote:
> This rewrites the ppc_set_compat() function so that instead of open coding
> the various compatibility modes, it reads the relevant data from a table.
> This is a first step in consolidating the information on compatibility
> modes scattered across the code into a single place.
> 
> It also makes one change to the logic.  The old code masked the bits to be
> set in the PCR (Processor Compatibility Register) by which bits are valid
> on the host CPU.  This made no sense, since it was done regardless of
> whether our guest CPU was the same as the host CPU or not.  Futhermore,

s/Futhermore/Furthermore/


> the actual PCR bits are only relevant for TCG[1] - KVM instead uses the
> compatibility mode we tell it in kvmppc_set_compat().  When using TCG
> host cpu information usually isn't even present.
> 
> While we're at it, we put the new implementation in a new file to make the
> enormouse translate_init.c a little smaller.

s/enormouse/enormous/


> 
> [1] Actually it doesn't even do anything in TCG, but it will if / when we
>     get to implementing compatibility mode logic at that level.
> 
> Signed-off-by: David Gibson <address@hidden>

Reviewed-by: Alexey Kardashevskiy <address@hidden>

> ---
>  target-ppc/Makefile.objs    |  1 +
>  target-ppc/compat.c         | 91 
> +++++++++++++++++++++++++++++++++++++++++++++
>  target-ppc/cpu.h            |  6 ++-
>  target-ppc/translate_init.c | 41 --------------------
>  4 files changed, 97 insertions(+), 42 deletions(-)
>  create mode 100644 target-ppc/compat.c
> 
> diff --git a/target-ppc/Makefile.objs b/target-ppc/Makefile.objs
> index e667e69..feb5c30 100644
> --- a/target-ppc/Makefile.objs
> +++ b/target-ppc/Makefile.objs
> @@ -15,3 +15,4 @@ obj-y += misc_helper.o
>  obj-y += mem_helper.o
>  obj-$(CONFIG_USER_ONLY) += user_only_helper.o
>  obj-y += gdbstub.o
> +obj-$(TARGET_PPC64) += compat.o
> diff --git a/target-ppc/compat.c b/target-ppc/compat.c
> new file mode 100644
> index 0000000..f3fd9c6
> --- /dev/null
> +++ b/target-ppc/compat.c
> @@ -0,0 +1,91 @@
> +/*
> + *  PowerPC CPU initialization for qemu.
> + *
> + *  Copyright 2016, David Gibson, Red Hat Inc. <address@hidden>
> + *
> + * This library is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU Lesser General Public
> + * License as published by the Free Software Foundation; either
> + * version 2 of the License, or (at your option) any later version.
> + *
> + * This library is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, see 
> <http://www.gnu.org/licenses/>.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "sysemu/kvm.h"
> +#include "kvm_ppc.h"
> +#include "sysemu/cpus.h"
> +#include "qemu/error-report.h"
> +#include "qapi/error.h"
> +#include "cpu-models.h"
> +
> +typedef struct {
> +    uint32_t pvr;
> +    uint64_t pcr;
> +} CompatInfo;
> +
> +static const CompatInfo compat_table[] = {
> +    { /* POWER6, ISA2.05 */
> +        .pvr = CPU_POWERPC_LOGICAL_2_05,
> +        .pcr = PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_COMPAT_2_05
> +               | PCR_TM_DIS | PCR_VSX_DIS,
> +    },
> +    { /* POWER7, ISA2.06 */
> +        .pvr = CPU_POWERPC_LOGICAL_2_06,
> +        .pcr = PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_TM_DIS,
> +    },
> +    {
> +        .pvr = CPU_POWERPC_LOGICAL_2_06_PLUS,
> +        .pcr = PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | PCR_TM_DIS,
> +    },
> +    { /* POWER8, ISA2.07 */
> +        .pvr = CPU_POWERPC_LOGICAL_2_07,
> +        .pcr = PCR_COMPAT_2_07,
> +    },
> +};
> +
> +static const CompatInfo *compat_by_pvr(uint32_t pvr)
> +{
> +    int i;
> +
> +    for (i = 0; i < ARRAY_SIZE(compat_table); i++) {
> +        if (compat_table[i].pvr == pvr) {
> +            return &compat_table[i];
> +        }
> +    }
> +    return NULL;
> +}
> +
> +void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
> +{
> +    const CompatInfo *compat = compat_by_pvr(compat_pvr);
> +    CPUPPCState *env = &cpu->env;
> +    PowerPCCPUClass *pcc = POWERPC_CPU_GET_CLASS(cpu);
> +    uint64_t pcr;
> +
> +    if (!compat_pvr) {
> +        pcr = 0;
> +    } else if (!compat) {
> +        error_setg(errp, "Unknown compatibility PVR 0x%08"PRIx32, 
> compat_pvr);
> +        return;
> +    } else {
> +        pcr = compat->pcr;
> +    }
> +
> +    cpu->compat_pvr = compat_pvr;
> +    env->spr[SPR_PCR] = pcr & pcc->pcr_mask;
> +
> +    if (kvm_enabled()) {
> +        int ret = kvmppc_set_compat(cpu, cpu->compat_pvr);
> +        if (ret < 0) {
> +            error_setg_errno(errp, -ret,
> +                             "Unable to set CPU compatibility mode in KVM");
> +        }
> +    }
> +}
> diff --git a/target-ppc/cpu.h b/target-ppc/cpu.h
> index f7656cb..15d5e4b 100644
> --- a/target-ppc/cpu.h
> +++ b/target-ppc/cpu.h
> @@ -1243,7 +1243,6 @@ void ppc_store_msr (CPUPPCState *env, target_ulong 
> value);
>  void ppc_cpu_list (FILE *f, fprintf_function cpu_fprintf);
>  int ppc_get_compat_smt_threads(PowerPCCPU *cpu);
>  #if defined(TARGET_PPC64)
> -void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp);
>  #endif
>  
>  /* Time-base and decrementer management */
> @@ -1314,6 +1313,11 @@ static inline int cpu_mmu_index (CPUPPCState *env, 
> bool ifetch)
>      return ifetch ? env->immu_idx : env->dmmu_idx;
>  }
>  
> +/* Compatibility modes */
> +#if defined(TARGET_PPC64)
> +void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp);
> +#endif /* defined(TARGET_PPC64) */
> +
>  #include "exec/cpu-all.h"
>  
>  
> /*****************************************************************************/
> diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
> index c35065d..a70eafb 100644
> --- a/target-ppc/translate_init.c
> +++ b/target-ppc/translate_init.c
> @@ -9972,47 +9972,6 @@ int ppc_get_compat_smt_threads(PowerPCCPU *cpu)
>      return ret;
>  }
>  
> -#ifdef TARGET_PPC64
> -void ppc_set_compat(PowerPCCPU *cpu, uint32_t compat_pvr, Error **errp)
> -{
> -    int ret = 0;
> -    CPUPPCState *env = &cpu->env;
> -    PowerPCCPUClass *host_pcc;
> -
> -    cpu->compat_pvr = compat_pvr;
> -
> -    switch (compat_pvr) {
> -    case CPU_POWERPC_LOGICAL_2_05:
> -        env->spr[SPR_PCR] = PCR_TM_DIS | PCR_VSX_DIS | PCR_COMPAT_2_07 |
> -                            PCR_COMPAT_2_06 | PCR_COMPAT_2_05;
> -        break;
> -    case CPU_POWERPC_LOGICAL_2_06:
> -    case CPU_POWERPC_LOGICAL_2_06_PLUS:
> -        env->spr[SPR_PCR] = PCR_TM_DIS | PCR_COMPAT_2_07 | PCR_COMPAT_2_06;
> -        break;
> -    case CPU_POWERPC_LOGICAL_2_07:
> -        env->spr[SPR_PCR] = PCR_COMPAT_2_07;
> -        break;
> -    default:
> -        env->spr[SPR_PCR] = 0;
> -        break;
> -    }
> -
> -    host_pcc = kvm_ppc_get_host_cpu_class();
> -    if (host_pcc) {
> -        env->spr[SPR_PCR] &= host_pcc->pcr_mask;
> -    }
> -
> -    if (kvm_enabled()) {
> -        ret = kvmppc_set_compat(cpu, cpu->compat_pvr);
> -        if (ret < 0) {
> -            error_setg_errno(errp, -ret,
> -                             "Unable to set CPU compatibility mode in KVM");
> -        }
> -    }
> -}
> -#endif
> -
>  static gint ppc_cpu_compare_class_pvr(gconstpointer a, gconstpointer b)
>  {
>      ObjectClass *oc = (ObjectClass *)a;
> 


-- 
Alexey