Re: [PATCH 3/5] nmi: add MCE class for implementing machine check injection commands

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

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On Thu, Mar 26, 2020 at 12:41:45AM +1000, Nicholas Piggin wrote:
> Like commit 9cb805fd26 ("cpus: Define callback for QEMU "nmi" command")
> this implements a machine check injection command framework and defines
> a monitor command for ppc.
> 
> Signed-off-by: Nicholas Piggin <npiggin@gmail.com>

So, AFAICT, both x86 and ppc have something called an MCE, and while
I'm guessing they're somewhat related, they don't work quite the same
way - different information provided to the handler and so forth.

I think it's reasonable to overload the "mce" HMP command based on
target for the different types.  However, I think calling the
interface classes which are specific to the ppc type just "mce" could
be pretty confusing.

In addition, I think this is adding an HMP command to inject the event
without any corresponding way of injecting via QMP.  I believe that's
frowned upon.

> ---
>  hmp-commands.hx              | 20 +++++++++++-
>  hw/core/nmi.c                | 61 ++++++++++++++++++++++++++++++++++++
>  include/hw/nmi.h             | 20 ++++++++++++
>  include/monitor/hmp-target.h |  1 -
>  include/monitor/hmp.h        |  1 +
>  monitor/hmp-cmds.c           |  1 +
>  target/ppc/monitor.c         | 11 +++++++
>  7 files changed, 113 insertions(+), 2 deletions(-)
> 
> diff --git a/hmp-commands.hx b/hmp-commands.hx
> index 7f0f3974ad..4a9089b431 100644
> --- a/hmp-commands.hx
> +++ b/hmp-commands.hx
> @@ -1581,12 +1581,30 @@ ERST
>          .cmd        = hmp_mce,
>      },
>  
> -#endif
>  SRST
>  ``mce`` *cpu* *bank* *status* *mcgstatus* *addr* *misc*
>    Inject an MCE on the given CPU (x86 only).
>  ERST
>  
> +#endif
> +
> +#if defined(TARGET_PPC)
> +
> +    {
> +        .name       = "mce",
> +        .args_type  = "cpu_index:i,srr1_mask:l,dsisr:i,dar:l,recovered:i",
> +        .params     = "cpu srr1_mask dsisr dar recovered",
> +        .help       = "inject a MCE on the given CPU",
> +        .cmd        = hmp_mce,
> +    },
> +
> +SRST
> +``mce`` *cpu* *srr1_mask* *dsisr* *dar* *recovered*
> +  Inject an MCE on the given CPU (PPC only).
> +ERST
> +
> +#endif
> +
>      {
>          .name       = "getfd",
>          .args_type  = "fdname:s",
> diff --git a/hw/core/nmi.c b/hw/core/nmi.c
> index 481c4b3c7e..2a79500967 100644
> --- a/hw/core/nmi.c
> +++ b/hw/core/nmi.c
> @@ -86,3 +86,64 @@ static void nmi_register_types(void)
>  }
>  
>  type_init(nmi_register_types)
> +
> +struct do_mce_s {
> +    const QDict *qdict;
> +    Error *err;
> +    bool handled;
> +};
> +
> +static void mce_children(Object *o, struct do_mce_s *ns);
> +
> +static int do_mce(Object *o, void *opaque)
> +{
> +    struct do_mce_s *ms = opaque;
> +    MCEState *m = (MCEState *) object_dynamic_cast(o, TYPE_MCE);
> +
> +    if (m) {
> +        MCEClass *mc = MCE_GET_CLASS(m);
> +
> +        ms->handled = true;
> +        mc->mce_monitor_handler(m, ms->qdict, &ms->err);
> +        if (ms->err) {
> +            return -1;
> +        }
> +    }
> +    mce_children(o, ms);
> +
> +    return 0;
> +}
> +
> +static void mce_children(Object *o, struct do_mce_s *ms)
> +{
> +    object_child_foreach(o, do_mce, ms);
> +}
> +
> +void mce_monitor_handle(const QDict *qdict, Error **errp)
> +{
> +    struct do_mce_s ms = {
> +        .qdict = qdict,
> +        .err = NULL,
> +        .handled = false
> +    };
> +
> +    mce_children(object_get_root(), &ms);
> +    if (ms.handled) {
> +        error_propagate(errp, ms.err);
> +    } else {
> +        error_setg(errp, QERR_UNSUPPORTED);
> +    }
> +}
> +
> +static const TypeInfo mce_info = {
> +    .name          = TYPE_MCE,
> +    .parent        = TYPE_INTERFACE,
> +    .class_size    = sizeof(MCEClass),
> +};
> +
> +static void mce_register_types(void)
> +{
> +    type_register_static(&mce_info);
> +}
> +
> +type_init(mce_register_types)
> diff --git a/include/hw/nmi.h b/include/hw/nmi.h
> index fe37ce3ad8..de39d95c9a 100644
> --- a/include/hw/nmi.h
> +++ b/include/hw/nmi.h
> @@ -43,4 +43,24 @@ typedef struct NMIClass {
>  
>  void nmi_monitor_handle(int cpu_index, Error **errp);
>  
> +
> +#define TYPE_MCE "mce"
> +
> +#define MCE_CLASS(klass) \
> +     OBJECT_CLASS_CHECK(MCEClass, (klass), TYPE_MCE)
> +#define MCE_GET_CLASS(obj) \
> +    OBJECT_GET_CLASS(MCEClass, (obj), TYPE_MCE)
> +#define MCE(obj) \
> +     INTERFACE_CHECK(MCEState, (obj), TYPE_MCE)
> +
> +typedef struct MCEState MCEState;
> +
> +typedef struct MCEClass {
> +    InterfaceClass parent_class;
> +
> +    void (*mce_monitor_handler)(MCEState *n, const QDict *qdict, Error **errp);
> +} MCEClass;
> +
> +void mce_monitor_handle(const QDict *qdict, Error **errp);
> +
>  #endif /* NMI_H */
> diff --git a/include/monitor/hmp-target.h b/include/monitor/hmp-target.h
> index 8b7820a3ad..afb8f5bca2 100644
> --- a/include/monitor/hmp-target.h
> +++ b/include/monitor/hmp-target.h
> @@ -45,7 +45,6 @@ CPUState *mon_get_cpu(void);
>  
>  void hmp_info_mem(Monitor *mon, const QDict *qdict);
>  void hmp_info_tlb(Monitor *mon, const QDict *qdict);
> -void hmp_mce(Monitor *mon, const QDict *qdict);
>  void hmp_info_local_apic(Monitor *mon, const QDict *qdict);
>  void hmp_info_io_apic(Monitor *mon, const QDict *qdict);
>  
> diff --git a/include/monitor/hmp.h b/include/monitor/hmp.h
> index e33ca5a911..f747a5e214 100644
> --- a/include/monitor/hmp.h
> +++ b/include/monitor/hmp.h
> @@ -54,6 +54,7 @@ void hmp_ringbuf_read(Monitor *mon, const QDict *qdict);
>  void hmp_cont(Monitor *mon, const QDict *qdict);
>  void hmp_system_wakeup(Monitor *mon, const QDict *qdict);
>  void hmp_nmi(Monitor *mon, const QDict *qdict);
> +void hmp_mce(Monitor *mon, const QDict *qdict);
>  void hmp_set_link(Monitor *mon, const QDict *qdict);
>  void hmp_balloon(Monitor *mon, const QDict *qdict);
>  void hmp_loadvm(Monitor *mon, const QDict *qdict);
> diff --git a/monitor/hmp-cmds.c b/monitor/hmp-cmds.c
> index 58724031ea..3664ef2a4f 100644
> --- a/monitor/hmp-cmds.c
> +++ b/monitor/hmp-cmds.c
> @@ -52,6 +52,7 @@
>  #include "exec/ramlist.h"
>  #include "hw/intc/intc.h"
>  #include "hw/rdma/rdma.h"
> +#include "hw/nmi.h"
>  #include "migration/snapshot.h"
>  #include "migration/misc.h"
>  
> diff --git a/target/ppc/monitor.c b/target/ppc/monitor.c
> index a5a177d717..6daf543efc 100644
> --- a/target/ppc/monitor.c
> +++ b/target/ppc/monitor.c
> @@ -28,6 +28,8 @@
>  #include "qemu/ctype.h"
>  #include "monitor/hmp-target.h"
>  #include "monitor/hmp.h"
> +#include "qapi/qmp/qdict.h"
> +#include "hw/nmi.h"
>  
>  static target_long monitor_get_ccr(const struct MonitorDef *md, int val)
>  {
> @@ -72,6 +74,15 @@ void hmp_info_tlb(Monitor *mon, const QDict *qdict)
>      dump_mmu(env1);
>  }
>  
> +void hmp_mce(Monitor *mon, const QDict *qdict)
> +{
> +    Error *err = NULL;
> +
> +    mce_monitor_handle(qdict, &err);
> +
> +    hmp_handle_error(mon, err);
> +}
> +
>  const MonitorDef monitor_defs[] = {
>      { "fpscr", offsetof(CPUPPCState, fpscr) },
>      /* Next instruction pointer */

-- 
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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