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

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

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On Fri, Nov 04, 2016 at 01:57:45PM +1100, Alexey Kardashevskiy wrote:
> 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/

Thanks, spelling corrections applied.

> 
> 
> > 
> > [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 <david@gibson.dropbear.id.au>
> 
> Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> 
> > ---
> >  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. <dgibson@redhat.com>
> > + *
> > + * 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;
> > 
> 
> 

-- 
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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