Re: [Qemu-devel] [PATCH v5 07/16] spapr_rtas: add ibm, configure-connector RTAS interface

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

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On Mon, Feb 16, 2015 at 08:27:43AM -0600, Michael Roth wrote:
> This interface is used to fetch an OF device-tree nodes that describes a
> newly-attached device to guest. It is called multiple times to walk the
> device-tree node and fetch individual properties into a 'workarea'/buffer
> provided by the guest.
> 
> The device-tree is generated by QEMU and passed to an sPAPRDRConnector during
> the initial hotplug operation, and the state of these RTAS calls is tracked by
> the sPAPRDRConnector. When the last of these properties is successfully
> fetched, we report as special return value to the guest and transition
> the device to a 'configured' state on the QEMU/DRC side.
> 
> See docs/specs/ppc-spapr-hotplug.txt for a complete description of
> this interface.
> 
> Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
> ---
>  hw/ppc/spapr_rtas.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 81 insertions(+)
> 
> diff --git a/hw/ppc/spapr_rtas.c b/hw/ppc/spapr_rtas.c
> index f80beb2..b8551b0 100644
> --- a/hw/ppc/spapr_rtas.c
> +++ b/hw/ppc/spapr_rtas.c
> @@ -418,6 +418,85 @@ static void rtas_get_sensor_state(PowerPCCPU *cpu, sPAPREnvironment *spapr,
>      rtas_st(rets, 1, entity_sense);
>  }
>  
> +/* configure-connector work area offsets, int32_t units for field
> + * indexes, bytes for field offset/len values.
> + *
> + * as documented by PAPR+ v2.7, 13.5.3.5
> + */
> +#define CC_IDX_NODE_NAME_OFFSET 2
> +#define CC_IDX_PROP_NAME_OFFSET 2
> +#define CC_IDX_PROP_LEN 3
> +#define CC_IDX_PROP_DATA_OFFSET 4
> +#define CC_VAL_DATA_OFFSET ((CC_IDX_PROP_DATA_OFFSET + 1) * 4)
> +#define CC_WA_LEN 4096
> +
> +static void rtas_ibm_configure_connector(PowerPCCPU *cpu,
> +                                         sPAPREnvironment *spapr,
> +                                         uint32_t token, uint32_t nargs,
> +                                         target_ulong args, uint32_t nret,
> +                                         target_ulong rets)
> +{
> +    uint64_t wa_addr = ((uint64_t)rtas_ld(args, 1) << 32) | rtas_ld(args, 0);

You need to check nargs and nret first.

> +    uint64_t wa_offset;
> +    uint32_t drc_index;
> +    sPAPRDRConnector *drc;
> +    sPAPRDRConnectorClass *drck;
> +    sPAPRDRCCResponse resp;
> +    const struct fdt_property *prop = NULL;
> +    char *prop_name = NULL;
> +    int prop_len, rc;
> +
> +    drc_index = rtas_ld(wa_addr, 0);
> +    drc = spapr_dr_connector_by_index(drc_index);
> +    if (!drc) {
> +        DPRINTF("rtas_ibm_configure_connector: invalid sensor/DRC index: %xh\n",
> +                drc_index);
> +        rc = RTAS_OUT_PARAM_ERROR;
> +        goto out;
> +    }
> +    drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> +    resp = drck->configure_connector(drc, &prop_name, &prop, &prop_len);

You may have answered this last time round, but if so I forgot the
reason.

Why does the awkward iteration need to go down to the drck callback?
Coudln't the drck callback part just supply the fdt fragment blob,
then have generic code which streams it out via iteration?

Obviously we have to support the horrid PAPR interface, but it would
be nice to confine the PAPR derived horridness to as small an area as
we can.


> +    switch (resp) {
> +    case SPAPR_DR_CC_RESPONSE_NEXT_CHILD:
> +        /* provide the name of the next OF node */
> +        wa_offset = CC_VAL_DATA_OFFSET;
> +        rtas_st(wa_addr, CC_IDX_NODE_NAME_OFFSET, wa_offset);
> +        rtas_st_buffer_direct(wa_addr + wa_offset, CC_WA_LEN - wa_offset,
> +                              (uint8_t *)prop_name, strlen(prop_name) + 1);
> +        break;
> +    case SPAPR_DR_CC_RESPONSE_NEXT_PROPERTY:
> +        /* provide the name of the next OF property */
> +        wa_offset = CC_VAL_DATA_OFFSET;
> +        rtas_st(wa_addr, CC_IDX_PROP_NAME_OFFSET, wa_offset);
> +        rtas_st_buffer_direct(wa_addr + wa_offset, CC_WA_LEN - wa_offset,
> +                              (uint8_t *)prop_name, strlen(prop_name) + 1);
> +
> +        /* provide the length and value of the OF property. data gets placed
> +         * immediately after NULL terminator of the OF property's name string
> +         */
> +        wa_offset += strlen(prop_name) + 1,
> +        rtas_st(wa_addr, CC_IDX_PROP_LEN, prop_len);
> +        rtas_st(wa_addr, CC_IDX_PROP_DATA_OFFSET, wa_offset);
> +        rtas_st_buffer_direct(wa_addr + wa_offset, CC_WA_LEN - wa_offset,
> +                              (uint8_t *)((struct fdt_property *)prop)->data,
> +                              prop_len);
> +        break;
> +    case SPAPR_DR_CC_RESPONSE_PREV_PARENT:
> +    case SPAPR_DR_CC_RESPONSE_ERROR:
> +    case SPAPR_DR_CC_RESPONSE_SUCCESS:
> +        break;
> +    default:
> +        /* drck->configure_connector() should not return anything else */
> +        g_assert(false);
> +    }
> +
> +    rc = resp;
> +out:
> +    g_free(prop_name);
> +    rtas_st(rets, 0, rc);
> +}
> +
>  static struct rtas_call {
>      const char *name;
>      spapr_rtas_fn fn;
> @@ -551,6 +630,8 @@ static void core_rtas_register_types(void)
>                          rtas_set_indicator);
>      spapr_rtas_register(RTAS_GET_SENSOR_STATE, "get-sensor-state",
>                          rtas_get_sensor_state);
> +    spapr_rtas_register(RTAS_IBM_CONFIGURE_CONNECTOR, "ibm,configure-connector",
> +                        rtas_ibm_configure_connector);
>  }
>  
>  type_init(core_rtas_register_types)

-- 
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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