ACK: [SRU][P][PATCH 0/1] Documentation update for [Ubuntu25.04] "virsh attach-interface" requires a reboot to reflect the attached interfaces on the guest (LP: #2111231)

[Cengiz Can]

On 17-07-25 13:29:19, Massimiliano Pellizzer wrote:
> BugLink: https://bugs.launchpad.net/bugs/2111231
> 
> [ Impact ]
> 
> powerpc/pseries/dlpar: Search DRC index from ibm,drc-indexes for IO add
> 
> IO hotplug add event is handled in the user space with drmgr tool.
> After the device is enabled, the user space uses /sys/kernel/dlpar
> interface with “dt add index <drc_index>” to update the device tree.
> The kernel interface (dlpar_hp_dt_add()) finds the parent node for
> the specified ‘drc_index’ from ibm,drc-info property. The recent FW
> provides this property from 2017 onwards. But KVM guest code in
> some releases is still using the older SLOF firmware which has
> ibm,drc-indexes property instead of ibm,drc-info.
> 
> If the ibm,drc-info is not available, this patch adds changes to
> search ‘drc_index’ from the indexes array in ibm,drc-indexes
> property to support old FW.
> 
> [ Fix ]
> 
> Backport from linux-next commit:
> - 41a1452759a8b1 powerpc/pseries/dlpar: Search DRC index from ibm,drc-indexes for IO add
> 
> [ Test Plan ]
> 
> Perform a virsh attach-device on an L2 VM (on a Power instance)
> and verify that the corresponding hotplug operation does go through.

Acked-by: Cengiz Can <cengiz.can at canonical.com>

> 
> [ Regression Potential ]
> 
> The patch introduces a fallback mechanism that scans ibm,drc-indexes
> only when ibm,drc-info is missing, minimizing disruption to existing behavior.
> However, in malformed or ambiguous device trees,
> the fallback logic might match unintended nodes,
> potentially misconfiguring the hotplug target.
> 
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