Re: [PATCH v3 14/15] qapi: introduce DEVICE_ON event

[Philippe Mathieu-Daudé]

On 9/2/23 21:08, Vladimir Sementsov-Ogievskiy wrote:
> We have DEVICE_DELETED event, that signals that device_del command is
> actually complited. But we don't have a counter-part for device_add.
> Still it's sensible for SHPC and PCIe-native hotplug, as there are time
> when the device in some intermediate state. Let's add an event that say
> that the device is finally powered on, power indicator is on and
> everything is OK for next manipulation on that device.
>
> Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> ---
>   qapi/qdev.json | 24 ++++++++++++++++++++++++
>   hw/pci/pcie.c  | 12 ++++++++++++
>   hw/pci/shpc.c  | 12 ++++++++++++
>   3 files changed, 48 insertions(+)
>
> diff --git a/qapi/qdev.json b/qapi/qdev.json
> index 40dc34f091..94da7ca228 100644
> --- a/qapi/qdev.json
> +++ b/qapi/qdev.json
> @@ -220,3 +220,27 @@
>   ##
>   { 'event': 'HOTPLUG_STATE',
>     'data': 'HotplugState' }
> +
> +
> +##
> +# @DEVICE_ON:
> +#
> +# Emitted whenever the device insertion completion is acknowledged by the 
> guest.
> +# For now only emitted for SHPC and PCIe-native hotplug.
> +#
> +# @device: device name
> +#
> +# @path: device path
> +#
> +# Since: 8.0
> +#
> +# Example:
> +#
> +# <- { "event": "DEVICE_ON",
> +#      "data": { "device": "virtio-net-pci-0",
> +#                "path": "/machine/peripheral/virtio-net-pci-0" },

Why provide both device & path? Could the type_name be helpful?

> +#      "timestamp": { "seconds": 1265044230, "microseconds": 450486 } }
> +#
> +##
> +{ 'event': 'DEVICE_ON',
> +  'data': { '*device': 'str', 'path': 'str' } }
> diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> index 37e2979b3c..bc7e60ff9d 100644
> --- a/hw/pci/pcie.c
> +++ b/hw/pci/pcie.c
> @@ -45,6 +45,13 @@ static bool pcie_sltctl_powered_off(uint16_t sltctl)
>           (sltctl & PCI_EXP_SLTCTL_PIC) == PCI_EXP_SLTCTL_PWR_IND_OFF;
>   }
>   
> +static bool pcie_sltctl_powered_on(uint16_t sltctl)
> +{
> +    return (sltctl & PCI_EXP_SLTCTL_PCC) == PCI_EXP_SLTCTL_PWR_ON &&
> +        (sltctl & PCI_EXP_SLTCTL_PIC) == PCI_EXP_SLTCTL_PWR_IND_ON &&
> +        (sltctl & PCI_EXP_SLTCTL_AIC) == PCI_EXP_SLTCTL_ATTN_IND_OFF;
> +}
> +
>   static HotplugLedState pcie_led_state_to_qapi(uint16_t value)
>   {
>       switch (value) {
> @@ -816,6 +823,11 @@ void pcie_cap_slot_write_config(PCIDevice *dev,
>                               0, 0, /* no state */
>                               pcie_power_state_to_qapi(old_pcc),
>                               pcie_power_state_to_qapi(pcc));
> +    if ((sltsta & PCI_EXP_SLTSTA_PDS) && pcie_sltctl_powered_on(val) &&
> +        !pcie_sltctl_powered_on(old_slt_ctl) && child_dev)
> +    {
> +        qapi_event_send_device_on(child_dev->id, child_dev->canonical_path);
> +    }

Beside this series aims, but this probably belong to the QDev layer;
if we ever model power domains & co some day.
Then this would be refactored to something like:

          qdev_set_power_on(DEVICE(child_dev));

which itself emit the event.

Regards,

Phil.