Re: [PATCH v14 5/7] ppc: spapr: Handle "ibm, nmi-register" and "ibm, nmi-interlock" RTAS calls

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

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On Wed, Sep 18, 2019 at 01:42:43PM +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.
> 
> Signed-off-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr.c         |    9 ++++++++
>  hw/ppc/spapr_rtas.c    |   57 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h |    5 +++-
>  3 files changed, 70 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 9f2e5d2..6992b32 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2941,6 +2941,15 @@ static void spapr_machine_init(MachineState *machine)
>  
>          /* Resize rtas blob to accommodate error log */
>          spapr->rtas_size = RTAS_ERROR_LOG_MAX;
> +
> +        /* Set fwnmi capability in KVM */
> +        if (kvmppc_set_fwnmi() < 0) {
> +            error_report("Could not enable FWNMI capability");
> +            exit(1);
> +        }
> +
> +        /* Register ibm,nmi-register and ibm,nmi-interlock RTAS calls */
> +        spapr_fwnmi_register();

This setup only needs to happen if CAP_MCE_FWNMI is turned on, so it
makes more sense in the .apply hooks for that rather than general
machine_init, I think.

>      }
>  
>      spapr->rtas_blob = g_malloc(spapr->rtas_size);
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index d8fb8a8..b569538 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -400,6 +400,55 @@ 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 = spapr_get_rtas_addr();
> +
> +    if (!rtas_addr) {
> +        rtas_st(rets, 0, RTAS_OUT_NOT_SUPPORTED);
> +        return;
> +    }
> +
> +    if (spapr_get_cap(spapr, SPAPR_CAP_FWNMI_MCE) == SPAPR_CAP_OFF) {
> +        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->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;
> @@ -544,6 +593,14 @@ hwaddr spapr_get_rtas_addr(void)
>      return (hwaddr)fdt32_to_cpu(*rtas_data);
>  }
>  
> +void spapr_fwnmi_register(void)
> +{
> +    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);
> +}
> +
>  static void core_rtas_register_types(void)
>  {
>      spapr_rtas_register(RTAS_DISPLAY_CHARACTER, "display-character",
> diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> index ffefde7..dada821 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -655,8 +655,10 @@ 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
> @@ -908,4 +910,5 @@ void spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
>  
>  void spapr_set_all_lpcrs(target_ulong value, target_ulong mask);
>  hwaddr spapr_get_rtas_addr(void);
> +void spapr_fwnmi_register(void);
>  #endif /* HW_SPAPR_H */
> 

-- 
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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