Re: [Qemu-devel] [PATCH v2 2/4] spapr: Handle "ibm, nmi-register" and "ibm, nmi-interlock" RTAS calls

[David Gibson]

On Wed, Dec 16, 2015 at 11:38:22AM +0530, Aravinda Prasad wrote:
> This patch adds support in QEMU to handle "ibm,nmi-register"
> and "ibm,nmi-interlock" RTAS calls.
> 
> The machine check notification address is saved when the
> OS issues "ibm,nmi-register" RTAS call.
> 
> This patch also handles the case when multiple processors
> experience machine check at or about the same time by
> handling "ibm,nmi-interlock" call. In such cases, as per
> PAPR, subsequent processors serialize waiting for the first
> processor to issue the "ibm,nmi-interlock" call. The second
> processor waits till the first processor, which also
> received a machine check error, is done reading the error
> log. The first processor issues "ibm,nmi-interlock" call
> when the error log is consumed. This patch implements the
> releasing part of the error-log while subsequent patch
> (which builds error log) handles the locking part.
> 
> Signed-off-by: Aravinda Prasad <address@hidden>
> ---
>  hw/ppc/spapr_rtas.c    |   36 ++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h |   10 +++++++++-
>  2 files changed, 45 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index 9869bc9..17c4672 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -597,6 +597,38 @@ out:
>      rtas_st(rets, 0, rc);
>  }
>  
> +static void rtas_ibm_nmi_register(PowerPCCPU *cpu,
> +                                  sPAPRMachineState *spapr,
> +                                  uint32_t token, uint32_t nargs,
> +                                  target_ulong args,
> +                                  uint32_t nret, target_ulong rets)
> +{
> +    spapr->mc_in_progress = false;
> +    qemu_cond_init(&spapr->mc_delivery_cond);

I think initializing mc_in_progress and the condition variable should
go in the overall initialization (in fact during system reset) instead
of here.  Things using these shouldn't be invoked until after the
nmi_register, but it's safer to have the qemu internal variables
initialized beforehand.

> +    spapr->guest_machine_check_addr = rtas_ld(args, 1);
> +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
> +}

It also looks like you need to add code to clear
guest_machine_check_addr if the system is reset

> +static void rtas_ibm_nmi_interlock(PowerPCCPU *cpu,
> +                                   sPAPRMachineState *spapr,
> +                                   uint32_t token, uint32_t nargs,
> +                                   target_ulong args,
> +                                   uint32_t nret, target_ulong rets)
> +{
> +    if (!spapr->guest_machine_check_addr) {
> +        /* NMI register not called */
> +        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> +    } else {
> +        /*
> +         * VCPU issuing "ibm,nmi-interlock" is done with NMI handling,
> +         * hence unset mc_in_progress.
> +         */
> +        spapr->mc_in_progress = false;
> +        qemu_cond_signal(&spapr->mc_delivery_cond);
> +        rtas_st(rets, 0, RTAS_OUT_SUCCESS);
> +    }
> +}
> +
>  static struct rtas_call {
>      const char *name;
>      spapr_rtas_fn fn;
> @@ -747,6 +779,10 @@ static void core_rtas_register_types(void)
>                          rtas_get_sensor_state);
>      spapr_rtas_register(RTAS_IBM_CONFIGURE_CONNECTOR, 
> "ibm,configure-connector",
>                          rtas_ibm_configure_connector);
> +    spapr_rtas_register(RTAS_IBM_NMI_REGISTER, "ibm,nmi-register",
> +                        rtas_ibm_nmi_register);
> +    spapr_rtas_register(RTAS_IBM_NMI_INTERLOCK, "ibm,nmi-interlock",
> +                        rtas_ibm_nmi_interlock);
>  }
>  
>  type_init(core_rtas_register_types)
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index b5cadd7..de84a4e 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -74,6 +74,12 @@ struct sPAPRMachineState {
>      /* RTAS state */
>      QTAILQ_HEAD(, sPAPRConfigureConnectorState) ccs_list;
>  
> +    /* State related to "ibm,nmi-register" and "ibm,nmi-interlock" calls */
> +    target_ulong guest_machine_check_addr;
> +    bool mc_in_progress;
> +    int mc_cpu;

mc_cpu doesn't appear to be used.

I think guest_machine_check_addr and mc_in_progress will also need to
be added to migration state.

> +    QemuCond mc_delivery_cond;
> +
>      /*< public >*/
>      char *kvm_type;
>  };
> @@ -458,8 +464,10 @@ int spapr_allocate_irq_block(int num, bool lsi, bool 
> msi);
>  #define RTAS_IBM_SET_SLOT_RESET                 (RTAS_TOKEN_BASE + 0x23)
>  #define RTAS_IBM_CONFIGURE_PE                   (RTAS_TOKEN_BASE + 0x24)
>  #define RTAS_IBM_SLOT_ERROR_DETAIL              (RTAS_TOKEN_BASE + 0x25)
> +#define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x26)
> +#define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x27)
>  
> -#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x26)
> +#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x28)
>  
>  /* RTAS ibm,get-system-parameter token values */
>  #define RTAS_SYSPARM_SPLPAR_CHARACTERISTICS      20
> 

-- 
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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