Re: [Qemu-devel] [PATCHv3 2/4] pseries: Move CPU compatibility property to machine

[David Gibson]

On Thu, Apr 27, 2017 at 12:23:51PM -0500, Michael Roth wrote:
> Quoting David Gibson (2017-04-27 02:28:41)
> > Server class POWER CPUs have a "compat" property, which is used to set the
> > backwards compatibility mode for the processor.  However, this only makes
> > sense for machine types which don't give the guest access to hypervisor
> > privilege - otherwise the compatibility level is under the guest's control.
> > 
> > To reflect this, this removes the CPU 'compat' property and instead
> > creates a 'max-cpu-compat' property on the pseries machine.  Strictly
> > speaking this breaks compatibility, but AFAIK the 'compat' option was
> > never (directly) used with -device or device_add.
> > 
> > The option was used with -cpu.  So, to maintain compatibility, this patch
> > adds a hack to the cpu option parsing to strip out any compat options
> > supplied with -cpu and set them on the machine property instead of the new
> > removed cpu property.
> 
> "now-deprecated cpu property" maybe?

Good idea.

> > Signed-off-by: David Gibson <address@hidden>
> > ---
> >  hw/ppc/spapr.c              |  6 +++-
> >  hw/ppc/spapr_cpu_core.c     | 41 ++++++++++++++++++++--
> >  hw/ppc/spapr_hcall.c        |  2 +-
> >  include/hw/ppc/spapr.h      | 12 ++++---
> >  target/ppc/compat.c         | 65 +++++++++++++++++++++++++++++++++++
> >  target/ppc/cpu.h            |  6 ++--
> >  target/ppc/translate_init.c | 84 
> > +++++++++++++--------------------------------
> >  7 files changed, 145 insertions(+), 71 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index 80d12d0..547fa27 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -2117,7 +2117,7 @@ static void ppc_spapr_init(MachineState *machine)
> >          machine->cpu_model = kvm_enabled() ? "host" : smc->tcg_default_cpu;
> >      }
> > 
> > -    ppc_cpu_parse_features(machine->cpu_model);
> > +    spapr_cpu_parse_features(spapr);
> > 
> >      spapr_init_cpus(spapr);
> > 
> > @@ -2480,6 +2480,10 @@ static void spapr_machine_initfn(Object *obj)
> >                                      " place of standard EPOW events when 
> > possible"
> >                                      " (required for memory hot-unplug 
> > support)",
> >                                      NULL);
> > +
> > +    object_property_add(obj, "max-cpu-compat", "str",
> > +                        ppc_compat_prop_get, ppc_compat_prop_set,
> > +                        NULL, &spapr->max_compat_pvr, &error_fatal);
> >  }
> > 
> >  static void spapr_machine_finalizefn(Object *obj)
> > diff --git a/hw/ppc/spapr_cpu_core.c b/hw/ppc/spapr_cpu_core.c
> > index 4389ef4..ba610bc 100644
> > --- a/hw/ppc/spapr_cpu_core.c
> > +++ b/hw/ppc/spapr_cpu_core.c
> > @@ -20,6 +20,43 @@
> >  #include "sysemu/numa.h"
> >  #include "qemu/error-report.h"
> > 
> > +void spapr_cpu_parse_features(sPAPRMachineState *spapr)
> > +{
> > +    /*
> > +     * Backwards compatibility hack:
> > +
> 
> Missing "*"

Oops, fixed.

> > +     *   CPUs had a "compat=" property which didn't make sense for
> > +     *   anything except pseries.  It was replaced by "max-cpu-compat"
> > +     *   machine option.  This supports old command lines like
> > +     *       -cpu POWER8,compat=power7
> > +     *   By stripping the compat option and applying it to the machine
> > +     *   before passing it on to the cpu level parser.
> > +     */
> > +    gchar **inpieces;
> > +    int n, i;
> > +    gchar *compat_str = NULL;
> > +
> > +    inpieces = g_strsplit(MACHINE(spapr)->cpu_model, ",", 0);
> > +    n = g_strv_length(inpieces);
> > +
> > +    /* inpieces[0] is the actual model string */
> 
> The comment seems a bit out of place unless we start with i = 1

A good point.  Yes, it should start from i=1.

> > +    for (i = 0; i < n; i++) {
> > +        if (g_str_has_prefix(inpieces[i], "compat=")) {
> > +            compat_str = inpieces[i];
> > +        }
> > +    }
> > +
> > +    if (compat_str) {
> > +        char *val = compat_str + strlen("compat=");
> > +        object_property_set_str(OBJECT(spapr), val, "max-cpu-compat",
> > +                                &error_fatal);
> > +    }
> > +
> > +    ppc_cpu_parse_features(MACHINE(spapr)->cpu_model);
> > +
> > +    g_strfreev(inpieces);
> > +}
> > +
> >  static void spapr_cpu_reset(void *opaque)
> >  {
> >      sPAPRMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> > @@ -70,10 +107,10 @@ static void spapr_cpu_init(sPAPRMachineState *spapr, 
> > PowerPCCPU *cpu,
> >      /* Enable PAPR mode in TCG or KVM */
> >      cpu_ppc_set_papr(cpu, PPC_VIRTUAL_HYPERVISOR(spapr));
> > 
> > -    if (cpu->max_compat) {
> > +    if (spapr->max_compat_pvr) {
> >          Error *local_err = NULL;
> > 
> > -        ppc_set_compat(cpu, cpu->max_compat, &local_err);
> > +        ppc_set_compat(cpu, spapr->max_compat_pvr, &local_err);
> >          if (local_err) {
> >              error_propagate(errp, local_err);
> >              return;
> > diff --git a/hw/ppc/spapr_hcall.c b/hw/ppc/spapr_hcall.c
> > index 9f18f75..d4dc12b 100644
> > --- a/hw/ppc/spapr_hcall.c
> > +++ b/hw/ppc/spapr_hcall.c
> > @@ -1059,7 +1059,7 @@ static target_ulong 
> > h_client_architecture_support(PowerPCCPU *cpu,
> >      target_ulong list = ppc64_phys_to_real(args[0]);
> >      target_ulong ov_table;
> >      bool explicit_match = false; /* Matched the CPU's real PVR */
> > -    uint32_t max_compat = cpu->max_compat;
> > +    uint32_t max_compat = spapr->max_compat_pvr;
> >      uint32_t best_compat = 0;
> >      int i;
> >      sPAPROptionVector *ov1_guest, *ov5_guest, *ov5_cas_old, *ov5_updates;
> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > index 5802f88..40d5f89 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -86,16 +86,19 @@ struct sPAPRMachineState {
> >      uint64_t rtc_offset; /* Now used only during incoming migration */
> >      struct PPCTimebase tb;
> >      bool has_graphics;
> > -    sPAPROptionVector *ov5;         /* QEMU-supported option vectors */
> > -    sPAPROptionVector *ov5_cas;     /* negotiated (via CAS) option vectors 
> > */
> > -    bool cas_reboot;
> > -    bool cas_legacy_guest_workaround;
> > 
> >      Notifier epow_notifier;
> >      QTAILQ_HEAD(, sPAPREventLogEntry) pending_events;
> >      bool use_hotplug_event_source;
> >      sPAPREventSource *event_sources;
> > 
> > +    /* ibm,client-architecture-support option negotiation */
> > +    bool cas_reboot;
> > +    bool cas_legacy_guest_workaround;
> > +    sPAPROptionVector *ov5;         /* QEMU-supported option vectors */
> > +    sPAPROptionVector *ov5_cas;     /* negotiated (via CAS) option vectors 
> > */
> > +    uint32_t max_compat_pvr;
> > +
> >      /* Migration state */
> >      int htab_save_index;
> >      bool htab_first_pass;
> > @@ -633,6 +636,7 @@ void 
> > spapr_hotplug_req_add_by_count_indexed(sPAPRDRConnectorType drc_type,
> >                                              uint32_t count, uint32_t 
> > index);
> >  void spapr_hotplug_req_remove_by_count_indexed(sPAPRDRConnectorType 
> > drc_type,
> >                                                 uint32_t count, uint32_t 
> > index);
> > +void spapr_cpu_parse_features(sPAPRMachineState *spapr);
> >  void *spapr_populate_hotplug_cpu_dt(CPUState *cs, int *fdt_offset,
> >                                      sPAPRMachineState *spapr);
> > 
> > diff --git a/target/ppc/compat.c b/target/ppc/compat.c
> > index e8ec1e1..476dead 100644
> > --- a/target/ppc/compat.c
> > +++ b/target/ppc/compat.c
> > @@ -24,9 +24,11 @@
> >  #include "sysemu/cpus.h"
> >  #include "qemu/error-report.h"
> >  #include "qapi/error.h"
> > +#include "qapi/visitor.h"
> >  #include "cpu-models.h"
> > 
> >  typedef struct {
> > +    const char *name;
> >      uint32_t pvr;
> >      uint64_t pcr;
> >      uint64_t pcr_level;
> > @@ -38,6 +40,7 @@ static const CompatInfo compat_table[] = {
> >       * Ordered from oldest to newest - the code relies on this
> >       */
> >      { /* POWER6, ISA2.05 */
> > +        .name = "power6",
> >          .pvr = CPU_POWERPC_LOGICAL_2_05,
> >          .pcr = PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 |
> >                 PCR_COMPAT_2_05 | PCR_TM_DIS | PCR_VSX_DIS,
> > @@ -45,18 +48,21 @@ static const CompatInfo compat_table[] = {
> >          .max_threads = 2,
> >      },
> >      { /* POWER7, ISA2.06 */
> > +        .name = "power7",
> >          .pvr = CPU_POWERPC_LOGICAL_2_06,
> >          .pcr = PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | 
> > PCR_TM_DIS,
> >          .pcr_level = PCR_COMPAT_2_06,
> >          .max_threads = 4,
> >      },
> >      {
> > +        .name = "power7+",
> >          .pvr = CPU_POWERPC_LOGICAL_2_06_PLUS,
> >          .pcr = PCR_COMPAT_3_00 | PCR_COMPAT_2_07 | PCR_COMPAT_2_06 | 
> > PCR_TM_DIS,
> >          .pcr_level = PCR_COMPAT_2_06,
> >          .max_threads = 4,
> >      },
> >      { /* POWER8, ISA2.07 */
> > +        .name = "power8",
> >          .pvr = CPU_POWERPC_LOGICAL_2_07,
> >          .pcr = PCR_COMPAT_3_00 | PCR_COMPAT_2_07,
> >          .pcr_level = PCR_COMPAT_2_07,
> > @@ -189,3 +195,62 @@ int ppc_compat_max_threads(PowerPCCPU *cpu)
> > 
> >      return n_threads;
> >  }
> > +
> > +void ppc_compat_prop_get(Object *obj, Visitor *v, const char *name,
> > +                         void *opaque, Error **errp)
> > +{
> > +    uint32_t compat_pvr = *((uint32_t *)opaque);
> > +    const char *value;
> > +
> > +    if (!compat_pvr) {
> > +        value = "";
> > +    } else {
> > +        const CompatInfo *compat = compat_by_pvr(compat_pvr);
> > +
> > +        g_assert(compat);
> > +
> > +        value = compat->name;
> > +    }
> > +
> > +    visit_type_str(v, name, (char **)&value, errp);
> > +}
> > +
> > +void ppc_compat_prop_set(Object *obj, Visitor *v, const char *name,
> > +                         void *opaque, Error **errp)
> > +{
> > +    Error *error = NULL;
> > +    char *value;
> > +    uint32_t compat_pvr;
> > +
> > +    visit_type_str(v, name, &value, &error);
> > +    if (error) {
> > +        error_propagate(errp, error);
> > +        return;
> > +    }
> > +
> > +    if (strcmp(value, "") == 0) {
> > +        compat_pvr = 0;
> > +    } else {
> > +        int i;
> > +        const CompatInfo *compat = NULL;
> > +
> > +        for (i = 0; i < ARRAY_SIZE(compat_table); i++) {
> > +            if (strcmp(value, compat_table[i].name) == 0) {
> > +                compat = &compat_table[i];
> > +                break;
> > +
> > +            }
> > +        }
> > +
> > +        if (!compat) {
> > +            error_setg(errp, "Invalid compatibility mode \"%s\"", value);
> > +            goto out;
> > +        }
> > +        compat_pvr = compat->pvr;
> > +    }
> > +
> > +    *((uint32_t *)opaque) = compat_pvr;
> > +
> > +out:
> > +    g_free(value);
> > +}
> > diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> > index e0ff041..e953e75 100644
> > --- a/target/ppc/cpu.h
> > +++ b/target/ppc/cpu.h
> > @@ -1185,7 +1185,6 @@ typedef struct PPCVirtualHypervisorClass 
> > PPCVirtualHypervisorClass;
> >   * PowerPCCPU:
> >   * @env: #CPUPPCState
> >   * @cpu_dt_id: CPU index used in the device tree. KVM uses this index too
> > - * @max_compat: Maximal supported logical PVR from the command line
> >   * @compat_pvr: Current logical PVR, zero if in "raw" mode
> >   *
> >   * A PowerPC CPU.
> > @@ -1197,7 +1196,6 @@ struct PowerPCCPU {
> > 
> >      CPUPPCState env;
> >      int cpu_dt_id;
> > -    uint32_t max_compat;
> >      uint32_t compat_pvr;
> >      PPCVirtualHypervisor *vhyp;
> >      Object *intc;
> > @@ -1369,6 +1367,10 @@ void ppc_set_compat(PowerPCCPU *cpu, uint32_t 
> > compat_pvr, Error **errp);
> >  void ppc_set_compat_all(uint32_t compat_pvr, Error **errp);
> >  #endif
> >  int ppc_compat_max_threads(PowerPCCPU *cpu);
> > +void ppc_compat_prop_get(Object *obj, Visitor *v,
> > +                         const char *name, void *opaque, Error **err);
> > +void ppc_compat_prop_set(Object *obj, Visitor *v,
> > +                         const char *name, void *opaque, Error **err);
> >  #endif /* defined(TARGET_PPC64) */
> > 
> >  #include "exec/cpu-all.h"
> > diff --git a/target/ppc/translate_init.c b/target/ppc/translate_init.c
> > index e82e3e6..a92c825 100644
> > --- a/target/ppc/translate_init.c
> > +++ b/target/ppc/translate_init.c
> > @@ -8413,73 +8413,35 @@ POWERPC_FAMILY(POWER5P)(ObjectClass *oc, void *data)
> >      pcc->l1_icache_size = 0x10000;
> >  }
> > 
> > -static void powerpc_get_compat(Object *obj, Visitor *v, const char *name,
> > -                               void *opaque, Error **errp)
> > -{
> > -    char *value = (char *)"";
> > -    Property *prop = opaque;
> > -    uint32_t *max_compat = qdev_get_prop_ptr(DEVICE(obj), prop);
> > -
> > -    switch (*max_compat) {
> > -    case CPU_POWERPC_LOGICAL_2_05:
> > -        value = (char *)"power6";
> > -        break;
> > -    case CPU_POWERPC_LOGICAL_2_06:
> > -        value = (char *)"power7";
> > -        break;
> > -    case CPU_POWERPC_LOGICAL_2_07:
> > -        value = (char *)"power8";
> > -        break;
> > -    case 0:
> > -        break;
> > -    default:
> > -        error_report("Internal error: compat is set to %x", *max_compat);
> > -        abort();
> > -        break;
> > -    }
> > -
> > -    visit_type_str(v, name, &value, errp);
> > -}
> > -
> > -static void powerpc_set_compat(Object *obj, Visitor *v, const char *name,
> > -                               void *opaque, Error **errp)
> > +/*
> > + * The CPU used to have a "compat" property which set the
> > + * compatibility mode PVR.  However, this was conceptually broken - it
> > + * only makes sense on the pseries machine type (otherwise the guest
> > + * owns the PCR and can control the compatibility mode itself).  It's
> > + * been replaced with the 'max-cpu-compat' property on the pseries
> > + * machine type.  For backwards compatibility, pseries specially
> > + * parses the -cpu parameter and converts old compat= parameters into
> > + * the appropriate machine parameters.  This stub implementation of
> > + * the parameter catches any uses on explicitly created CPUs.
> > + */
> > +static void getset_compat_deprecated(Object *obj, Visitor *v, const char 
> > *name,
> > +                                     void *opaque, Error **errp)
> >  {
> > -    Error *error = NULL;
> > -    char *value = NULL;
> > -    Property *prop = opaque;
> > -    uint32_t *max_compat = qdev_get_prop_ptr(DEVICE(obj), prop);
> > -
> > -    visit_type_str(v, name, &value, &error);
> > -    if (error) {
> > -        error_propagate(errp, error);
> > -        return;
> > -    }
> > -
> > -    if (strcmp(value, "power6") == 0) {
> > -        *max_compat = CPU_POWERPC_LOGICAL_2_05;
> > -    } else if (strcmp(value, "power7") == 0) {
> > -        *max_compat = CPU_POWERPC_LOGICAL_2_06;
> > -    } else if (strcmp(value, "power8") == 0) {
> > -        *max_compat = CPU_POWERPC_LOGICAL_2_07;
> > -    } else {
> > -        error_setg(errp, "Invalid compatibility mode \"%s\"", value);
> > -    }
> > -
> > -    g_free(value);
> > +    error_report("CPU 'compat' property is deprecated and has no effect; 
> > use max-cpu-compat machine property instead");
> 
> Isn't the "and has no effect" portion a bit misleading? AFAICT it does
> have an effect still, it just shouldn't be used anymore.

No.  Used as a property on the CPU object it really does have no
effect.  It's just that if you attach it to -cpu XXX, rather than to a
-device specific-cpu-type, then it gets automatically translated to
the new machine property.  These calls should only be triggered in the
second case.

> > +    visit_type_null(v, name, errp);
> >  }
> > 
> > -static PropertyInfo powerpc_compat_propinfo = {
> > +static PropertyInfo ppc_compat_deprecated_propinfo = {
> >      .name = "str",
> > -    .description = "compatibility mode, power6/power7/power8",
> > -    .get = powerpc_get_compat,
> > -    .set = powerpc_set_compat,
> > +    .description = "compatibility mode (deprecated)",
> > +    .get = getset_compat_deprecated,
> > +    .set = getset_compat_deprecated,
> >  };
> > -
> > -#define DEFINE_PROP_POWERPC_COMPAT(_n, _s, _f) \
> > -    DEFINE_PROP(_n, _s, _f, powerpc_compat_propinfo, uint32_t)
> > -
> >  static Property powerpc_servercpu_properties[] = {
> > -    DEFINE_PROP_POWERPC_COMPAT("compat", PowerPCCPU, max_compat),
> > +    {
> > +        .name = "compat",
> > +        .info = &ppc_compat_deprecated_propinfo,
> > +    },
> >      DEFINE_PROP_END_OF_LIST(),
> >  };
> > 
> 

-- 
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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