Re: [Qemu-devel] [Qemu-ppc] [PATCHv4 3/5] pseries: Move CPU compatibility property to machine

[Greg Kurz <groug@kaod.org>]

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On Thu, 01 Jun 2017 15:44:40 +1000
Suraj Jitindar Singh <sjitindarsingh@gmail.com> wrote:

> On Fri, 2017-05-26 at 15:23 +1000, David Gibson wrote:
> > 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 now deprecated cpu property.  
> 
> Generally looks good, a couple of comments below.
> 
> Suraj
> 
> > 
> > Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> > ---
> >  hw/ppc/spapr.c              |   6 ++-
> >  hw/ppc/spapr_cpu_core.c     |  56 +++++++++++++++++++++++-
> >  hw/ppc/spapr_hcall.c        |   8 ++--
> >  include/hw/ppc/spapr.h      |  12 ++++--
> >  target/ppc/compat.c         | 102
> > ++++++++++++++++++++++++++++++++++++++++++++
> >  target/ppc/cpu.h            |   5 ++-
> >  target/ppc/translate_init.c |  86 +++++++++++-----------------------
> > ---
> >  7 files changed, 202 insertions(+), 73 deletions(-)
> > 
> > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > index ab3aab1..3c4e88f 100644
> > --- a/hw/ppc/spapr.c
> > +++ b/hw/ppc/spapr.c
> > @@ -2134,7 +2134,7 @@ 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);
> >  
> > @@ -2497,6 +2497,10 @@ static void spapr_machine_initfn(Object *obj)
> >                                      " place of standard EPOW events
> > when possible"
> >                                      " (required for memory hot-
> > unplug support)",
> >                                      NULL);
> > +
> > +    ppc_compat_add_property(obj, "max-cpu-compat", &spapr-  
> > >max_compat_pvr,  
> > +                            "Maximum permitted CPU compatibility
> > mode",
> > +                            &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 ff7058e..ab4102b 100644
> > --- a/hw/ppc/spapr_cpu_core.c
> > +++ b/hw/ppc/spapr_cpu_core.c
> > @@ -20,6 +20,58 @@
> >  #include "sysemu/numa.h"
> >  #include "qemu/error-report.h"
> >  
> > +void spapr_cpu_parse_features(sPAPRMachineState *spapr)
> > +{
> > +    /*
> > +     * Backwards compatibility hack:
> > +     *
> > +     *   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 i, j;
> > +    gchar *compat_str = NULL;
> > +
> > +    inpieces = g_strsplit(MACHINE(spapr)->cpu_model, ",", 0);
> > +
> > +    /* inpieces[0] is the actual model string */
> > +    i = 1;
> > +    j = 1;
> > +    while (inpieces[i]) {
> > +        if (g_str_has_prefix(inpieces[i], "compat=")) {
> > +            /* in case of multiple compat= optipons */  
> 
> s/optipons/options?
> 
> > +            g_free(compat_str);
> > +            compat_str = inpieces[i];
> > +        } else {
> > +            j++;
> > +        }
> > +
> > +        /* Excise compat options from list */
> > +        inpieces[j] = inpieces[i];  
> 
> it's worth noting that where previously when specifying an invalid
> option you got:
> 
> qemu-system-ppc64: Expected key=value format, found *blah*
> 
> You now get a segfault here.
> 

Yeah. This basically does:

    inpieces[i + 1] = inpieces[i];

and we end up overwriting the terminal NULL pointer with a non-NULL
pointer.

What about simplifying the loop to:

    /* inpieces[0] is the actual model string */
    i = 1;
    while (inpieces[i]) {
        if (g_str_has_prefix(inpieces[i], "compat=")) {
            /* in case of multiple compat= optipons */
            g_free(compat_str);
            compat_str = inpieces[i];
            /* Excise compat options from list */
            inpieces[i] = inpieces[i + 1];
        }
        i++;
    }

> > +        i++;
> > +    }
> > +    inpieces[j] = NULL;
> > +
> > +    if (compat_str) {
> > +        char *val = compat_str + strlen("compat=");
> > +        gchar *newprops = g_strjoinv(",", inpieces);
> > +
> > +        object_property_set_str(OBJECT(spapr), val, "max-cpu-
> > compat",
> > +                                &error_fatal);
> > +
> > +        ppc_cpu_parse_features(newprops);
> > +        g_free(newprops);
> > +    } else {
> > +        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 +122,10 @@ 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 77d2d66..8129959 100644
> > --- a/hw/ppc/spapr_hcall.c
> > +++ b/hw/ppc/spapr_hcall.c
> > @@ -1044,11 +1044,11 @@ static target_ulong
> > h_signal_sys_reset(PowerPCCPU *cpu,
> >      }
> >  }
> >  
> > -static uint32_t cas_check_pvr(PowerPCCPU *cpu, target_ulong *addr,
> > -                              Error **errp)
> > +static uint32_t cas_check_pvr(sPAPRMachineState *spapr, PowerPCCPU
> > *cpu,
> > +                              target_ulong *addr, Error **errp)
> >  {
> >      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;
> >  
> > @@ -1104,7 +1104,7 @@ static target_ulong
> > h_client_architecture_support(PowerPCCPU *cpu,
> >      bool guest_radix;
> >      Error *local_err = NULL;
> >  
> > -    cas_pvr = cas_check_pvr(cpu, &addr, &local_err);
> > +    cas_pvr = cas_check_pvr(spapr, cpu, &addr, &local_err);
> >      if (local_err) {
> >          error_report_err(local_err);
> >          return H_HARDWARE;
> > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > index 98fb78b..4da92e2 100644
> > --- a/include/hw/ppc/spapr.h
> > +++ b/include/hw/ppc/spapr.h
> > @@ -87,16 +87,19 @@ 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;
> > @@ -639,6 +642,7 @@ 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..e72839f 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,
> > @@ -45,24 +48,28 @@ 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,
> >          .max_threads = 8,
> >      },
> >      { /* POWER9, ISA3.00 */
> > +        .name = "power9",
> >          .pvr = CPU_POWERPC_LOGICAL_3_00,
> >          .pcr = PCR_COMPAT_3_00,
> >          .pcr_level = PCR_COMPAT_3_00,
> > @@ -189,3 +196,98 @@ int ppc_compat_max_threads(PowerPCCPU *cpu)
> >  
> >      return n_threads;
> >  }
> > +
> > +static 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);
> > +}
> > +
> > +static 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);
> > +}
> > +
> > +void ppc_compat_add_property(Object *obj, const char *name,
> > +                             uint32_t *compat_pvr, const char
> > *basedesc,
> > +                             Error **errp)
> > +{
> > +    Error *local_err = NULL;
> > +    gchar *namesv[ARRAY_SIZE(compat_table) + 1];
> > +    gchar *names, *desc;
> > +    int i;
> > +
> > +    object_property_add(obj, name, "string",
> > +                        ppc_compat_prop_get, ppc_compat_prop_set,
> > NULL,
> > +                        compat_pvr, &local_err);
> > +    if (local_err) {
> > +        goto out;
> > +    }
> > +
> > +    for (i = 0; i < ARRAY_SIZE(compat_table); i++) {
> > +        /*
> > +         * Have to discard const here, because g_strjoinv() takes
> > +         * (gchar **), not (const gchar **) :(
> > +         */
> > +        namesv[i] = (gchar *)compat_table[i].name;
> > +    }
> > +    namesv[ARRAY_SIZE(compat_table)] = NULL;
> > +
> > +    names = g_strjoinv(", ", namesv);
> > +    desc = g_strdup_printf("%s. Valid values are %s.", basedesc,
> > names);
> > +    object_property_set_description(obj, name, desc, &local_err);
> > +
> > +    g_free(names);
> > +    g_free(desc);
> > +
> > +out:
> > +    error_propagate(errp, local_err);
> > +}
> > diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> > index 401e10e..4517b4b 100644
> > --- a/target/ppc/cpu.h
> > +++ b/target/ppc/cpu.h
> > @@ -1189,7 +1189,6 @@ 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.
> > @@ -1201,7 +1200,6 @@ struct PowerPCCPU {
> >  
> >      CPUPPCState env;
> >      int cpu_dt_id;
> > -    uint32_t max_compat;
> >      uint32_t compat_pvr;
> >      PPCVirtualHypervisor *vhyp;
> >      Object *intc;
> > @@ -1374,6 +1372,9 @@ 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_add_property(Object *obj, const char *name,
> > +                             uint32_t *compat_pvr, const char
> > *basedesc,
> > +                             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 56a0ab2..e837cd2 100644
> > --- a/target/ppc/translate_init.c
> > +++ b/target/ppc/translate_init.c
> > @@ -33,6 +33,7 @@
> >  #include "hw/qdev-properties.h"
> >  #include "hw/ppc/ppc.h"
> >  #include "mmu-book3s-v3.h"
> > +#include "sysemu/qtest.h"
> >  
> >  //#define PPC_DUMP_CPU
> >  //#define PPC_DEBUG_SPR
> > @@ -8413,73 +8414,38 @@ 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);
> > +    if (!qtest_enabled()) {
> > +        error_report("CPU 'compat' property is deprecated and has no
> > effect; "
> > +                     "use max-cpu-compat machine property instead");
> >      }
> > -
> > -    g_free(value);
> > +    visit_type_null(v, name, NULL);
> >  }
> >  
> > -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(),
> >  };
> >    


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