Re: [Qemu-devel] [PATCH v2 10/10] spapr_pci: perform unplug via the hotplug handler

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

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On Mon, Nov 05, 2018 at 11:20:44AM +0100, David Hildenbrand wrote:
> Introduce and use the "unplug" callback.
> 
> This is a preparation for multi-stage hotplug handlers, whereby the bus
> hotplug handler is overwritten by the machine hotplug handler. This handler
> will then pass control to the bus hotplug handler. So to get this running
> cleanly, we also have to make sure to go via the hotplug handler chain when
> actually unplugging a device after an unplug request. Lookup the hotplug
> handler and call "unplug".
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

Acked-by: David Gibson <david@gibson.dropbear.id.au>

> ---
>  hw/ppc/spapr_pci.c | 33 +++++++++++++++++++++------------
>  1 file changed, 21 insertions(+), 12 deletions(-)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 58afa46204..64b8591023 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -1370,18 +1370,9 @@ static int spapr_create_pci_child_dt(sPAPRPHBState *phb, PCIDevice *dev,
>  /* Callback to be called during DRC release. */
>  void spapr_phb_remove_pci_device_cb(DeviceState *dev)
>  {
> -    /* some version guests do not wait for completion of a device
> -     * cleanup (generally done asynchronously by the kernel) before
> -     * signaling to QEMU that the device is safe, but instead sleep
> -     * for some 'safe' period of time. unfortunately on a busy host
> -     * this sleep isn't guaranteed to be long enough, resulting in
> -     * bad things like IRQ lines being left asserted during final
> -     * device removal. to deal with this we call reset just prior
> -     * to finalizing the device, which will put the device back into
> -     * an 'idle' state, as the device cleanup code expects.
> -     */
> -    pci_device_reset(PCI_DEVICE(dev));
> -    object_unparent(OBJECT(dev));
> +    HotplugHandler *hotplug_ctrl = qdev_get_hotplug_handler(dev);
> +
> +    hotplug_handler_unplug(hotplug_ctrl, dev, &error_abort);
>  }
>  
>  static sPAPRDRConnector *spapr_phb_get_pci_func_drc(sPAPRPHBState *phb,
> @@ -1490,6 +1481,23 @@ out:
>      }
>  }
>  
> +static void spapr_pci_unplug(HotplugHandler *plug_handler,
> +                             DeviceState *plugged_dev, Error **errp)
> +{
> +    /* some version guests do not wait for completion of a device
> +     * cleanup (generally done asynchronously by the kernel) before
> +     * signaling to QEMU that the device is safe, but instead sleep
> +     * for some 'safe' period of time. unfortunately on a busy host
> +     * this sleep isn't guaranteed to be long enough, resulting in
> +     * bad things like IRQ lines being left asserted during final
> +     * device removal. to deal with this we call reset just prior
> +     * to finalizing the device, which will put the device back into
> +     * an 'idle' state, as the device cleanup code expects.
> +     */
> +    pci_device_reset(PCI_DEVICE(plugged_dev));
> +    object_unparent(OBJECT(plugged_dev));
> +}
> +
>  static void spapr_pci_unplug_request(HotplugHandler *plug_handler,
>                                       DeviceState *plugged_dev, Error **errp)
>  {
> @@ -1965,6 +1973,7 @@ static void spapr_phb_class_init(ObjectClass *klass, void *data)
>      dc->user_creatable = true;
>      set_bit(DEVICE_CATEGORY_BRIDGE, dc->categories);
>      hp->plug = spapr_pci_plug;
> +    hp->unplug = spapr_pci_unplug;
>      hp->unplug_request = spapr_pci_unplug_request;
>  }
>  

-- 
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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