[libvirt] [PATCH 06/11] qemu: Add handling for VSERPORT_CHANGE event

[Wang Rui]

On 2014/11/19 18:23, Peter Krempa wrote:
> New qemu added a new event that is emitted when a virtio serial channel
> is opened in the guest OS. This allows us to update the state of the
> port in the output-only XML element.
> 
> This patch implements the monitor callbacks and necessary handlers to
> update the state in the definition.
> ---
>  src/qemu/qemu_domain.h       |  1 +
>  src/qemu/qemu_driver.c       | 57 ++++++++++++++++++++++++++++++++++++++++++++
>  src/qemu/qemu_monitor.c      | 14 +++++++++++
>  src/qemu/qemu_monitor.h      | 10 ++++++++
>  src/qemu/qemu_monitor_json.c | 23 ++++++++++++++++++
>  src/qemu/qemu_process.c      | 44 ++++++++++++++++++++++++++++++++++
>  6 files changed, 149 insertions(+)
> 
> diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
> index ad45a66..e4ea4ce 100644
> --- a/src/qemu/qemu_domain.h
> +++ b/src/qemu/qemu_domain.h
> @@ -196,6 +196,7 @@ typedef enum {
>      QEMU_PROCESS_EVENT_GUESTPANIC,
>      QEMU_PROCESS_EVENT_DEVICE_DELETED,
>      QEMU_PROCESS_EVENT_NIC_RX_FILTER_CHANGED,
> +    QEMU_PROCESS_EVENT_SERIAL_CHANGED,
> 
>      QEMU_PROCESS_EVENT_LAST
>  } qemuProcessEventType;
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index a84fd47..31bf6bb 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4334,6 +4334,60 @@ processNicRxFilterChangedEvent(virQEMUDriverPtr driver,
>  }
> 
> 
> +static void
> +processSerialChangedEvent(virQEMUDriverPtr driver,
> +                          virDomainObjPtr vm,
> +                          char *devAlias,
> +                          bool connected)
> +{
> +    virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
> +    virDomainChrDeviceState newstate;
> +    virDomainDeviceDef dev;
> +
> +    if (connected)
> +        newstate = VIR_DOMAIN_CHR_DEVICE_STATE_CONNECTED;
> +    else
> +        newstate = VIR_DOMAIN_CHR_DEVICE_STATE_DISCONNECTED;
> +
> +    VIR_DEBUG("Changing serial port state %s in domain %p %s",
> +              devAlias, vm, vm->def->name);
> +
> +    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
> +        goto cleanup;
> +
> +    if (!virDomainObjIsActive(vm)) {
> +        VIR_DEBUG("Domain is not running");
> +        goto endjob;
> +    }
> +
> +    if (virDomainDefFindDevice(vm->def, devAlias, &dev, true) < 0)
> +        goto endjob;
> +
> +    /* we care only about certain devices */
> +    if (dev.type != VIR_DOMAIN_DEVICE_CHR ||
> +        dev.data.chr->deviceType != VIR_DOMAIN_CHR_DEVICE_TYPE_CHANNEL ||
> +        dev.data.chr->targetType != VIR_DOMAIN_CHR_CHANNEL_TARGET_TYPE_VIRTIO)
> +        goto endjob;
> +
> +    dev.data.chr->state = newstate;
> +
> +    if (virDomainSaveStatus(driver->xmlopt, cfg->stateDir, vm) < 0)
> +        VIR_WARN("unable to save domain status after removing device %s",
> +                 devAlias);
> +

Hi, Peter
IIUC, QEMU emitted the event and libvirt saved the state for the next time
being queryed. 'the output-only XML element' and 'SaveStatus' means the state
is not saved persistently.

In case of libvirtd being restarted after state is saved, we'll lose it. Could
we handle this case?