Re: [Qemu-ppc] [PATCH v2] spapr: manage hotplugged devices while the VM is not started

[Greg Kurz]

On Wed, 31 May 2017 11:25:16 +0200
Laurent Vivier <address@hidden> wrote:

> For QEMU, a hotlugged device is a device added using the HMP/QMP
> interface.
> For SPAPR, a hotplugged device is a device added while the
> machine is running. In this case QEMU doesn't update internal
> state but relies on the OS for this part
> 
> In the case of migration, when we (libvirt) hotplug a device
> on the source guest, we (libvirt) generally hotplug the same
> device on the destination guest. But in this case, the machine
> is stopped (RUN_STATE_INMIGRATE) and QEMU must not expect
> the OS will manage it as an hotplugged device as it will
> be "imported" by the migration.
> 
> This patch changes the meaning of "hotplugged" in spapr.c
> to manage a QEMU hotplugged device like a "coldplugged" one
> when the machine is awaiting an incoming migration.
> 
> Signed-off-by: Laurent Vivier <address@hidden>
> ---

Reviewed-by: Greg Kurz <address@hidden>

> v2:
> - don't replace dev->hotplugged to test if CPU hotplug
>   is supported.
> 
>  hw/ppc/spapr.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index ab3aab1..f0c543c 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2521,6 +2521,12 @@ static void spapr_nmi(NMIState *n, int cpu_index, 
> Error **errp)
>      }
>  }
>  
> +static bool spapr_coldplugged(DeviceState *dev)
> +{
> +    return runstate_check(RUN_STATE_INMIGRATE) ||
> +           !dev->hotplugged;
> +}
> +
>  static void spapr_add_lmbs(DeviceState *dev, uint64_t addr_start, uint64_t 
> size,
>                             uint32_t node, bool dedicated_hp_event_source,
>                             Error **errp)
> @@ -2531,6 +2537,7 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t 
> addr_start, uint64_t size,
>      int i, fdt_offset, fdt_size;
>      void *fdt;
>      uint64_t addr = addr_start;
> +    bool coldplugged = spapr_coldplugged(dev);
>  
>      for (i = 0; i < nr_lmbs; i++) {
>          drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
> @@ -2542,9 +2549,9 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t 
> addr_start, uint64_t size,
>                                                  SPAPR_MEMORY_BLOCK_SIZE);
>  
>          drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> -        drck->attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, errp);
> +        drck->attach(drc, dev, fdt, fdt_offset, coldplugged, errp);
>          addr += SPAPR_MEMORY_BLOCK_SIZE;
> -        if (!dev->hotplugged) {
> +        if (coldplugged) {
>              /* 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);
> @@ -2553,7 +2560,7 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t 
> addr_start, uint64_t size,
>      /* send hotplug notification to the
>       * guest only in case of hotplugged memory
>       */
> -    if (dev->hotplugged) {
> +    if (!coldplugged) {
>          if (dedicated_hp_event_source) {
>              drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
>                      addr_start / SPAPR_MEMORY_BLOCK_SIZE);
> @@ -2867,6 +2874,7 @@ static void spapr_core_plug(HotplugHandler 
> *hotplug_dev, DeviceState *dev,
>      int smt = kvmppc_smt_threads();
>      CPUArchId *core_slot;
>      int index;
> +    bool coldplugged = spapr_coldplugged(dev);
>  
>      core_slot = spapr_find_cpu_slot(MACHINE(hotplug_dev), cc->core_id, 
> &index);
>      if (!core_slot) {
> @@ -2888,7 +2896,7 @@ static void spapr_core_plug(HotplugHandler 
> *hotplug_dev, DeviceState *dev,
>  
>      if (drc) {
>          sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
> -        drck->attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, 
> &local_err);
> +        drck->attach(drc, dev, fdt, fdt_offset, coldplugged, &local_err);
>          if (local_err) {
>              g_free(fdt);
>              error_propagate(errp, local_err);
> @@ -2896,7 +2904,7 @@ static void spapr_core_plug(HotplugHandler 
> *hotplug_dev, DeviceState *dev,
>          }
>      }
>  
> -    if (dev->hotplugged) {
> +    if (!coldplugged) {
>          /*
>           * Send hotplug notification interrupt to the guest only in case
>           * of hotplugged CPUs.

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