Re: [Qemu-devel] [PATCH v7 1/6] ppc: spapr: Handle "ibm, nmi-register" and "ibm, nmi-interlock" RTAS calls

[David Gibson]

On Fri, Mar 22, 2019 at 12:03:39PM +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 that also received a machine check error waits
> till the first processor 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.c         |   25 +++++++++++++++++++++++++
>  hw/ppc/spapr_rtas.c    |   36 ++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h |   15 ++++++++++++++-
>  3 files changed, 75 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index adde36a..744dcad 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1788,6 +1788,16 @@ static void spapr_machine_reset(void)
>      first_ppc_cpu->env.gpr[5] = 0;
>  
>      spapr->cas_reboot = false;
> +
> +    spapr->mc_reset = 1;
> +    spapr->mc_status = -1;

I don't love adding these fields so early, when they're never actually
tested until later in the series.

> +    spapr->guest_machine_check_addr = -1;
> +
> +    /* Before destroying, signal vCPUs waiting on this condition */
> +    qemu_cond_broadcast(&spapr->mc_delivery_cond);
> +    /* It is safe to call destroy as broadcast unblocks all vCPUs */
> +    qemu_cond_destroy(&spapr->mc_delivery_cond);
> +    qemu_cond_init(&spapr->mc_delivery_cond);

Why do you need to destroy and re-create the condition variable?

>  }
>  
>  static void spapr_create_nvram(SpaprMachineState *spapr)
> @@ -2078,6 +2088,16 @@ static const VMStateDescription vmstate_spapr_dtb = {
>      },
>  };
>  
> +static const VMStateDescription vmstate_spapr_guest_mc_addr = {
> +    .name = "spapr_guest_mc_addr",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT64(guest_machine_check_addr, SpaprMachineState),

It looks like mc_reset and mc_status would also need migration, at
least once they actually do something.

> +        VMSTATE_END_OF_LIST()
> +    },
> +};
> +
>  static const VMStateDescription vmstate_spapr = {
>      .name = "spapr",
>      .version_id = 3,
> @@ -2110,6 +2130,7 @@ static const VMStateDescription vmstate_spapr = {
>          &vmstate_spapr_dtb,
>          &vmstate_spapr_cap_large_decr,
>          &vmstate_spapr_cap_ccf_assist,
> +        &vmstate_spapr_guest_mc_addr,
>          NULL
>      }
>  };
> @@ -3057,6 +3078,10 @@ static void spapr_machine_init(MachineState *machine)
>  
>          kvmppc_spapr_enable_inkernel_multitce();
>      }
> +
> +    spapr->mc_status = -1;
> +    spapr->mc_reset = 0;

Since this is a bool, you should use true/false rather than 0/1.

> +    qemu_cond_init(&spapr->mc_delivery_cond);
>  }
>  
>  static int spapr_kvm_type(MachineState *machine, const char *vm_type)
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index 24c45b1..fb594a4 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -348,6 +348,38 @@ static void rtas_get_power_level(PowerPCCPU *cpu, 
> SpaprMachineState *spapr,
>      rtas_st(rets, 1, 100);
>  }
>  
> +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_reset = 0;
> +    spapr->guest_machine_check_addr = rtas_ld(args, 1);
> +    rtas_st(rets, 0, RTAS_OUT_SUCCESS);
> +}
> +
> +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_status.
> +         */
> +        spapr->mc_status = -1;
> +        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;
> @@ -489,6 +521,10 @@ static void core_rtas_register_types(void)
>                          rtas_set_power_level);
>      spapr_rtas_register(RTAS_GET_POWER_LEVEL, "get-power-level",
>                          rtas_get_power_level);
> +    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 74ce638..ee5589d 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -186,6 +186,17 @@ struct SpaprMachineState {
>       * occurs during the unplug process. */
>      QTAILQ_HEAD(, SpaprDimmState) pending_dimm_unplugs;
>  
> +    /* State related to "ibm,nmi-register" and "ibm,nmi-interlock" calls */
> +    target_ulong guest_machine_check_addr;
> +    /*
> +     * mc_status is set to -1 if mc is not in progress, else is set to the 
> CPU
> +     * handling the mc.
> +     */
> +    int mc_status;
> +    /* mc_reset is set to 1 if machine reset is in progress */
> +    bool mc_reset;
> +    QemuCond mc_delivery_cond;
> +
>      /*< public >*/
>      char *kvm_type;
>      char *host_model;
> @@ -622,8 +633,10 @@ target_ulong spapr_hypercall(PowerPCCPU *cpu, 
> target_ulong opcode,
>  #define RTAS_IBM_CREATE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x27)
>  #define RTAS_IBM_REMOVE_PE_DMA_WINDOW           (RTAS_TOKEN_BASE + 0x28)
>  #define RTAS_IBM_RESET_PE_DMA_WINDOW            (RTAS_TOKEN_BASE + 0x29)
> +#define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x2A)
> +#define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x2B)
>  
> -#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2A)
> +#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2C)
>  
>  /* 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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