Re: [Qemu-ppc] [PATCH 1/5] spapr: ensure device trees are always associated with DRC

[David Gibson]

On Fri, Apr 15, 2016 at 01:33:01PM -0700, Jianjun Duan wrote:
> There are possible racing situations involving hotplug events and
> guest migration. For cases where a hotplug event is migrated, or
> the guest is in the process of fetching device tree at the time of
> migration, we need to ensure the device tree is created and
> associated with the corresponding DRC for devices that were
> hotplugged on the source, but 'coldplugged' on the target.
> 
> Signed-off-by: Jianjun Duan <address@hidden>

This seems fairly sensible - should be harmless and a bit cleaner
whether or not we strictly speaking need it.

However, it is likely to conflict with some of the device tree
construction cleanups I have in my pipeline, so it may well need
rework for that.

> ---
>  hw/ppc/spapr.c     | 16 ++++++----------
>  hw/ppc/spapr_pci.c | 12 +++++-------
>  2 files changed, 11 insertions(+), 17 deletions(-)
> 
> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> index feaab08..af4745c 100644
> --- a/hw/ppc/spapr.c
> +++ b/hw/ppc/spapr.c
> @@ -2132,15 +2132,6 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t 
> addr, uint64_t size,
>      int i, fdt_offset, fdt_size;
>      void *fdt;
>  
> -    /*
> -     * Check for DRC connectors and send hotplug notification to the
> -     * guest only in case of hotplugged memory. This allows cold plugged
> -     * memory to be specified at boot time.
> -     */
> -    if (!dev->hotplugged) {
> -        return;
> -    }
> -
>      for (i = 0; i < nr_lmbs; i++) {
>          drc = spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_LMB,
>                  addr/SPAPR_MEMORY_BLOCK_SIZE);
> @@ -2154,7 +2145,12 @@ static void spapr_add_lmbs(DeviceState *dev, uint64_t 
> addr, uint64_t size,
>          drck->attach(drc, dev, fdt, fdt_offset, !dev->hotplugged, errp);
>          addr += SPAPR_MEMORY_BLOCK_SIZE;
>      }
> -    spapr_hotplug_req_add_by_count(SPAPR_DR_CONNECTOR_TYPE_LMB, nr_lmbs);
> +    /* send hotplug notification to the
> +     * guest only in case of hotplugged memory
> +     */
> +    if (dev->hotplugged) {
> +       spapr_hotplug_req_add_by_count(SPAPR_DR_CONNECTOR_TYPE_LMB, nr_lmbs);
> +    }
>  }
>  
>  static void spapr_memory_plug(HotplugHandler *hotplug_dev, DeviceState *dev,
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 8c20d34..b179e42 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -1092,13 +1092,11 @@ static void spapr_phb_add_pci_device(sPAPRDRConnector 
> *drc,
>          spapr_tce_set_need_vfio(tcet, true);
>      }
>  
> -    if (dev->hotplugged) {
> -        fdt = create_device_tree(&fdt_size);
> -        fdt_start_offset = spapr_create_pci_child_dt(phb, pdev, fdt, 0);
> -        if (!fdt_start_offset) {
> -            error_setg(errp, "Failed to create pci child device tree node");
> -            goto out;
> -        }
> +    fdt = create_device_tree(&fdt_size);
> +    fdt_start_offset = spapr_create_pci_child_dt(phb, pdev, fdt, 0);
> +    if (!fdt_start_offset) {
> +        error_setg(errp, "Failed to create pci child device tree node");
> +        goto out;
>      }
>  
>      drck->attach(drc, DEVICE(pdev),

-- 
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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