Re: [PATCH v20 5/7] ppc: spapr: Handle "ibm,nmi-register" and "ibm,nmi-interlock" RTAS calls

[David Gibson]

On Fri, Jan 17, 2020 at 03:08:53PM +0530, Ganesh Goudar wrote:
> From: Aravinda Prasad <address@hidden>
> 
> 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.
> 
> Signed-off-by: Aravinda Prasad <address@hidden>
> [Register fwnmi RTAS calls in core_rtas_register_types()
>  where other RTAS calls are registered]
> Signed-off-by: Ganesh Goudar <address@hidden>
> ---
>  hw/ppc/spapr_caps.c    |  7 +++++
>  hw/ppc/spapr_rtas.c    | 59 ++++++++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h |  4 ++-
>  3 files changed, 69 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr_caps.c b/hw/ppc/spapr_caps.c
> index 3001098601..c43498da49 100644
> --- a/hw/ppc/spapr_caps.c
> +++ b/hw/ppc/spapr_caps.c
> @@ -502,6 +502,13 @@ static void cap_fwnmi_mce_apply(SpaprMachineState 
> *spapr, uint8_t val,
>      if (!val) {
>          return; /* Disabled by default */
>      }
> +
> +    if (kvm_enabled()) {
> +        if (kvmppc_set_fwnmi() < 0) {
> +            error_report("Could not enable fwnmi capability");
> +            exit(1);

We have uniform failure handling for the cap_apply functions so you
shouldn't roll your own.  Simply error_setg() on the supplied errp,
and the generic caps code will handle exiting out.

Also, I think you should explicitly mention KVM in this message, to
make it clear that's where the problem is occurring.  From the user's
point of view they've just *set* the spapr fwnmi capability so this
won't help them figure out why it isn't working.

Also, weren't you going to report a (non fatal) warning in the TCG
case, since TCG FWNMI behaviour doesn't precisely match true FWNMI
behaviour (though in a way that probably won't matter in practice).

> +        }
> +    }
>  }
>  
>  SpaprCapabilityInfo capability_table[SPAPR_CAP_NUM] = {
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index 2c066a372d..3f162d82f5 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -400,6 +400,61 @@ 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)
> +{
> +    hwaddr rtas_addr;
> +
> +    if (spapr_get_cap(spapr, SPAPR_CAP_FWNMI_MCE) == SPAPR_CAP_OFF) {
> +        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
> +        return;
> +    }
> +
> +    rtas_addr = spapr_get_rtas_addr();
> +    if (!rtas_addr) {
> +        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
> +        return;
> +    }
> +
> +    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_get_cap(spapr, SPAPR_CAP_FWNMI_MCE) == SPAPR_CAP_OFF) {
> +        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
> +        return;
> +    }
> +
> +    if (spapr->guest_machine_check_addr == -1) {
> +        /* NMI register not called */
> +        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> +        return;
> +    }
> +
> +    if (spapr->mc_status != cpu->vcpu_id) {
> +        /* The vCPU that hit the NMI should invoke "ibm,nmi-interlock" */
> +        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> +        return;
> +    }
> +
> +    /*
> +     * 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;
> @@ -528,6 +583,10 @@ 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 652a5514e8..f6f82d88aa 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -656,8 +656,10 @@ target_ulong spapr_hypercall(PowerPCCPU *cpu, 
> target_ulong opcode,
>  #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_SUSPEND_ME                     (RTAS_TOKEN_BASE + 0x2A)
> +#define RTAS_IBM_NMI_REGISTER                   (RTAS_TOKEN_BASE + 0x2B)
> +#define RTAS_IBM_NMI_INTERLOCK                  (RTAS_TOKEN_BASE + 0x2C)
>  
> -#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2B)
> +#define RTAS_TOKEN_MAX                          (RTAS_TOKEN_BASE + 0x2D)
>  
>  /* 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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