Re: [Qemu-ppc] [PATCH 4/6] spapr: Make DRC reset force DRC into known state

[Greg Kurz]

On Thu,  8 Jun 2017 15:09:28 +1000
David Gibson <address@hidden> wrote:

> The reset handler for DRCs attempts several state transitions which are
> subject to various checks and restrictions.  But at reset time we know
> there is no guest, so we can ignore most of the usual sequencing rules and
> just set the DRC back to a known state.  In fact, it's safer to do so.
> 
> The existing code also has several redundant checks for
> drc->awaiting_release inside a block which has already tested that.  This
> patch removes those and sets the DRC to a fixed initial state based only
> on whether a device is currently plugged or not.
> 
> With DRCs correctly reset to a state based on device presence, we don't
> need to force state transitions as cold plugged devices are processed.
> This allows us to remove all the callers of the set_*_state() methods from
> outside spapr_drc.c.
> 
> Signed-off-by: David Gibson <address@hidden>
> ---

Reviewed-by: Greg Kurz <address@hidden>

>  hw/ppc/spapr.c     | 15 ---------------
>  hw/ppc/spapr_drc.c | 28 ++++++++--------------------
>  2 files changed, 8 insertions(+), 35 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index 01dda9e..c988e38 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2545,12 +2545,6 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t 
> addr_start, uint64_t size,
>  
>          spapr_drc_attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, errp);
>          addr += SPAPR_MEMORY_BLOCK_SIZE;
> -        if (!dev->hotplugged) {
> -            sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> -            /* guests expect coldplugged LMBs to be pre-allocated */
> -            drck->set_allocation_state(drc, 
> SPAPR_DR_ALLOCATION_STATE_USABLE);
> -            drck->set_isolation_state(drc, 
> SPAPR_DR_ISOLATION_STATE_UNISOLATED);
> -        }
>      }
>      /* send hotplug notification to the
>       * guest only in case of hotplugged memory
> @@ -2901,15 +2895,6 @@ static void spapr_core_plug(HotplugHandler 
> *hotplug_dev, DeviceState *dev,
>           * of hotplugged CPUs.
>           */
>          spapr_hotplug_req_add_by_index(drc);
> -    } else {
> -        /*
> -         * Set the right DRC states for cold plugged CPU.
> -         */
> -        if (drc) {
> -            sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> -            drck->set_allocation_state(drc, 
> SPAPR_DR_ALLOCATION_STATE_USABLE);
> -            drck->set_isolation_state(drc, 
> SPAPR_DR_ISOLATION_STATE_UNISOLATED);
> -        }
>      }
>      core_slot->cpu = OBJECT(dev);
>  }
> diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
> index dc4ac77..7e17f34 100644
> --- a/hw/ppc/spapr_drc.c
> +++ b/hw/ppc/spapr_drc.c
> @@ -393,7 +393,6 @@ static bool release_pending(sPAPRDRConnector *drc)
>  static void reset(DeviceState *d)
>  {
>      sPAPRDRConnector *drc = SPAPR_DR_CONNECTOR(d);
> -    sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
>  
>      trace_spapr_drc_reset(spapr_drc_index(drc));
>  
> @@ -401,28 +400,17 @@ static void reset(DeviceState *d)
>      drc->ccs = NULL;
>  
>      /* immediately upon reset we can safely assume DRCs whose devices
> -     * are pending removal can be safely removed, and that they will
> -     * subsequently be left in an ISOLATED state. move the DRC to this
> -     * state in these cases (which will in turn complete any pending
> -     * device removals)
> +     * are pending removal can be safely removed.
>       */
>      if (drc->awaiting_release) {
> -        drck->set_isolation_state(drc, SPAPR_DR_ISOLATION_STATE_ISOLATED);
> -        /* generally this should also finalize the removal, but if the device
> -         * hasn't yet been configured we normally defer removal under the
> -         * assumption that this transition is taking place as part of device
> -         * configuration. so check if we're still waiting after this, and
> -         * force removal if we are
> -         */
> -        if (drc->awaiting_release) {
> -            spapr_drc_detach(drc, DEVICE(drc->dev), NULL);
> -        }
> +        spapr_drc_release(drc);
> +    }
>  
> -        /* non-PCI devices may be awaiting a transition to UNUSABLE */
> -        if (spapr_drc_type(drc) != SPAPR_DR_CONNECTOR_TYPE_PCI &&
> -            drc->awaiting_release) {
> -            drck->set_allocation_state(drc, 
> SPAPR_DR_ALLOCATION_STATE_UNUSABLE);
> -        }
> +    drc->isolation_state = drc->dev ? SPAPR_DR_ISOLATION_STATE_UNISOLATED
> +        : SPAPR_DR_ISOLATION_STATE_ISOLATED;
> +    if (spapr_drc_type(drc) != SPAPR_DR_CONNECTOR_TYPE_PCI) {
> +        drc->allocation_state = drc->dev ? SPAPR_DR_ALLOCATION_STATE_USABLE
> +            : SPAPR_DR_ALLOCATION_STATE_UNUSABLE;
>      }
>  }
>

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