Re: [Qemu-devel] [PATCH v9 1/6] 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, May 29, 2019 at 11:10:14AM +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 <aravinda@linux.vnet.ibm.com>
> Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
> ---
>  hw/ppc/spapr.c         |    7 +++++
>  hw/ppc/spapr_rtas.c    |   65 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/hw/ppc/spapr.h |    9 ++++++-
>  3 files changed, 80 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index e2b33e5..fae28a9 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -1808,6 +1808,11 @@ static void spapr_machine_reset(void)
>      first_ppc_cpu->env.gpr[5] = 0;
>  
>      spapr->cas_reboot = false;
> +
> +    spapr->guest_machine_check_addr = -1;
> +
> +    /* Signal all vCPUs waiting on this condition */
> +    qemu_cond_broadcast(&spapr->mc_delivery_cond);
>  }
>  
>  static void spapr_create_nvram(SpaprMachineState *spapr)
> @@ -3072,6 +3077,8 @@ static void spapr_machine_init(MachineState *machine)
>  
>          kvmppc_spapr_enable_inkernel_multitce();
>      }
> +
> +    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 5bc1a93..e7509cf 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -352,6 +352,38 @@ 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)
> +{
> +    hwaddr 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->guest_machine_check_addr == -1) {
> +        /* NMI register not called */
> +        rtas_st(rets, 0, RTAS_OUT_PARAM_ERROR);
> +    } else {
> +        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;
> @@ -470,6 +502,35 @@ void spapr_load_rtas(SpaprMachineState *spapr, void *fdt, hwaddr addr)
>      }
>  }
>  
> +hwaddr spapr_get_rtas_addr(void)
> +{
> +    SpaprMachineState *spapr = SPAPR_MACHINE(qdev_get_machine());
> +    int rtas_node;
> +    const struct fdt_property *rtas_addr_prop;
> +    void *fdt = spapr->fdt_blob;
> +    uint32_t rtas_addr;
> +
> +    /* fetch rtas addr from fdt */
> +    rtas_node = fdt_path_offset(fdt, "/rtas");
> +    if (rtas_node == 0) {
> +        return 0;

This is incorrect, a return code < 0 indicates an error which you
should check for.  A return code of 0 indicates the root node, which
could only happen if libfdt was badly buggy.

> +    }
> +
> +    rtas_addr_prop = fdt_get_property(fdt, rtas_node, "linux,rtas-base", NULL);

fdt_get_property is generally only needed for certain edge cases.
fdt_getprop() is a better option.

> +    if (!rtas_addr_prop) {
> +        return 0;
> +    }
> +
> +    /*
> +     * We assume that the OS called RTAS instantiate-rtas, but some other
> +     * OS might call RTAS instantiate-rtas-64 instead. This fine as of now
> +     * as SLOF only supports 32-bit variant.
> +     */
> +    rtas_addr = fdt32_to_cpu(*(uint32_t *)rtas_addr_prop->data);
> +    return (hwaddr)rtas_addr;
> +}
> +
> +
>  static void core_rtas_register_types(void)
>  {
>      spapr_rtas_register(RTAS_DISPLAY_CHARACTER, "display-character",
> @@ -493,6 +554,10 @@ 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 4f5becf..9dc5e30 100644
> --- a/include/hw/ppc/spapr.h
> +++ b/include/hw/ppc/spapr.h
> @@ -188,6 +188,10 @@ 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;
> +    QemuCond mc_delivery_cond;
> +
>      /*< public >*/
>      char *kvm_type;
>      char *host_model;
> @@ -624,8 +628,10 @@ 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
> @@ -876,4 +882,5 @@ void spapr_check_pagesize(SpaprMachineState *spapr, hwaddr pagesize,
>  #define SPAPR_OV5_XIVE_BOTH     0x80 /* Only to advertise on the platform */
>  
>  void spapr_set_all_lpcrs(target_ulong value, target_ulong mask);
> +uint64_t spapr_get_rtas_addr(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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