** Changed in: ubuntu-power-systems
Status: Triaged => Fix Committed
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https://bugs.launchpad.net/bugs/2111231
Title:
Documentation update for [Ubuntu25.04] "virsh attach-interface"
requires a reboot to reflect the attached interfaces on the guest
Status in The Ubuntu-power-systems project:
Fix Committed
Status in Release Notes for Ubuntu:
Fix Released
Status in linux package in Ubuntu:
Invalid
Status in linux source package in Plucky:
Fix Committed
Status in linux source package in Questing:
Invalid
Bug description:
[ 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.
[ 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.
---
== Comment: #2 - Amit Machhiwal <[email protected]> - 2025-05-12
04:46:34 ==
[Ubuntu25.04] "virsh attach-interface" requires a reboot to reflect the
attached
interfaces on the KVM guest running inside a PowerVM LPAR.
Abstract
--------
A reboot is required for the interfaces attached through "virsh
attach-interface" to be reflected on the KVM guest running inside a PowerVM
LPAR. Same behavior is observed with or without the "--live" option.
Linux releases affected
-----------------------
Ubuntu 25.04 (Kernel versions: all supported versions) and any distro which
uses
powerpc-utils/plucky,now 1.3.13-1 or later.
Symptoms
--------
When a virsh attach-device is performed on L2, the corresponding hotplug
operation does not go through and below errors are seen:
dmesg
-----
On device-attach
----------------
[ 165.672791] RTAS: event: 1, Type: Hotplug Event (229), Severity: 1
[ 165.900889] dlpar: Could not handle DLPAR request "dt add index
0x40010008"
[ 165.900889] dlpar: Could not handle DLPAR request "dt add index
0x40010008"
drmgr log
---------
Found drc_name C65544
is calling rtas_set_indicator(ISOLATE index 0x40010008)
is calling set_power(POWER_OFF index 0x40010008, power_domain 0xffffffff)
is calling card_present
Waiting for the card to appear...
get-sensor for 40010008: 0, 1
is calling set_power(POWER_ON index 0x40010008, power_domain 0xffffffff
calling rtas_set_indicator(UNISOLATE index 0x40010008)
Initiating kernel DLPAR "dt add index 0x40010008"
Failed to write to /sys/kernel/dlpar: Input/output error
add_device_tree_nodes failed at /proc/device-tree/pci@800000020000001
Internal software error. Contact your service representative.
Workaround
----------
This is a regression introduced in powerpc-utils/plucky,now 1.3.13-1 and a git
bisect pointed to the below commit:
a2d1b70cbc90 ("drmgr/pci: Add kernel interface support for device
tree update")
The above commit adds kernel interface for DLPAR IO add/remove if the it is
supported. In the failure case, the kernel interface adding the device tree
update is failing. This is because the kernel interface supports only
ibm,drc-info property to identify drc-index which is available in recent FW.
But
the older FW does not provide this interface but instead ibm,drc-indexes
property is available
So, if we need kernel interface for the older FW, changes are needed in kernel
for device tree update (add) or make changes in powerpc utils not to use
kernel
interface for the old FW (if drc-info not present) assuming we do not support
secure boot on older FW.
To workaround this problem, either revert to an older `drmgr` version prior to
commit `a2d1b70cbc90` or reboot your guest so that the device is listed inside
the KVM guest (L2).
Fix Outlook
-----------
A kernel patch has been sent upstream for fixing this bug and awaiting merge
into the mainline.
https://lore.kernel.org/linuxppc-
dev/[email protected]/
Thanks,
Amit
== Comment: #3 - Amit Machhiwal <[email protected]> - 2025-05-12
04:48:42 ==
@Haren,
Could you please review the above Ubuntu 25.04 documenatation update
and suggest any changes if required.
Thanks,
Amit
== Comment: #5 - Amit Machhiwal <[email protected]> - 2025-05-14
00:41:26 ==
[Ubuntu25.04] "virsh attach-interface" requires a reboot to reflect the
attached
interfaces on the KVM guest running inside a PowerVM LPAR.
Abstract
--------
A reboot is required for the interfaces attached through "virsh
attach-interface" to be reflected on the KVM guest running inside a PowerVM
LPAR. Same behavior is observed with or without the "--live" option.
Linux releases affected
-----------------------
Ubuntu 25.04 (Kernel versions: all supported versions) and any distro which
uses
powerpc-utils/plucky,now 1.3.13-1 or later.
Symptoms
--------
When a virsh attach-device is performed on L2, the corresponding hotplug
operation does not go through and below errors are seen:
dmesg
-----
On device-attach
----------------
[ 165.672791] RTAS: event: 1, Type: Hotplug Event (229), Severity: 1
[ 165.900889] dlpar: Could not handle DLPAR request "dt add index
0x40010008"
[ 165.900889] dlpar: Could not handle DLPAR request "dt add index
0x40010008"
drmgr log
---------
Found drc_name C65544
is calling rtas_set_indicator(ISOLATE index 0x40010008)
is calling set_power(POWER_OFF index 0x40010008, power_domain 0xffffffff)
is calling card_present
Waiting for the card to appear...
get-sensor for 40010008: 0, 1
is calling set_power(POWER_ON index 0x40010008, power_domain 0xffffffff
calling rtas_set_indicator(UNISOLATE index 0x40010008)
Initiating kernel DLPAR "dt add index 0x40010008"
Failed to write to /sys/kernel/dlpar: Input/output error
add_device_tree_nodes failed at /proc/device-tree/pci@800000020000001
Internal software error. Contact your service representative.
Workaround
----------
This is a regression introduced in powerpc-utils/plucky,now 1.3.13-1 and a git
bisect pointed to the below commit:
a2d1b70cbc90 ("drmgr/pci: Add kernel interface support for device
tree update")
The above commit adds kernel interface for DLPAR IO add/remove if the it is
supported. In the failure case, the kernel interface adding the device tree
update is failing. This is because the kernel interface supports only
ibm,drc-info property to identify drc-index which is available in recent FW.
But
the older FW does not provide this interface but instead ibm,drc-indexes
property is available
So, if we need kernel interface for the older FW, changes are needed in kernel
for device tree update (add) or make changes in powerpc utils not to use
kernel
interface for the old FW (if drc-info not present) assuming we do not support
secure boot on older FW.
To workaround this problem, either revert to an older `drmgr` version prior to
commit `a2d1b70cbc90` or reboot your guest so that the device is listed inside
the KVM guest (L2).
Note: If you are using kernel lockdown, it's not recommended to revert to an
older version of drmgr. In this case, rebooting the system is the only
workaround.
Fix Outlook
-----------
A kernel patch has been sent upstream for fixing this bug and awaiting merge
into the mainline.
https://lore.kernel.org/linuxppc-
dev/[email protected]/
Thanks,
Amit
== Comment: #8 - Amit Machhiwal <[email protected]> - 2025-05-19
01:09:53 ==
Copying the latest draft:
[Ubuntu25.04] "virsh attach-interface" requires a reboot to reflect the
attached
interfaces on the KVM guest running inside a PowerVM LPAR.
Abstract
--------
A reboot is required for the interfaces attached through "virsh
attach-interface" to be reflected on the KVM guest running inside a PowerVM
LPAR. Same behavior is observed with or without the "--live" option.
Linux releases affected
-----------------------
Ubuntu 25.04 (Kernel versions: all supported versions) and any distro which
uses
powerpc-utils 1.3.13 or later.
Symptoms
--------
When a virsh attach-device is performed on L2, the corresponding hotplug
operation does not go through and below errors are seen:
dmesg
-----
On device-attach
----------------
[ 165.672791] RTAS: event: 1, Type: Hotplug Event (229), Severity: 1
[ 165.900889] dlpar: Could not handle DLPAR request "dt add index
0x40010008"
[ 165.900889] dlpar: Could not handle DLPAR request "dt add index
0x40010008"
drmgr log
---------
Found drc_name C65544
is calling rtas_set_indicator(ISOLATE index 0x40010008)
is calling set_power(POWER_OFF index 0x40010008, power_domain 0xffffffff)
is calling card_present
Waiting for the card to appear...
get-sensor for 40010008: 0, 1
is calling set_power(POWER_ON index 0x40010008, power_domain 0xffffffff
calling rtas_set_indicator(UNISOLATE index 0x40010008)
Initiating kernel DLPAR "dt add index 0x40010008"
Failed to write to /sys/kernel/dlpar: Input/output error
add_device_tree_nodes failed at /proc/device-tree/pci@800000020000001
Internal software error. Contact your service representative.
Workaround
----------
This is a regression caused by a change done in powerpc-utils v1.3.13. The
hotplug operations work fine till powerpc-utils v1.3.12.
To workaround this problem, either revert to an older `drmgr` version v1.3.12
or
older or reboot your guest so that the device is recognised by the KVM guest
(L2).
Note: If you are using kernel lockdown, it's not recommended to revert to an
older version of drmgr. In this case, rebooting the system is the only
workaround.
Fix Outlook
-----------
A kernel patch has been sent upstream for fixing this bug and awaiting merge
into the mainline.
https://lore.kernel.org/linuxppc-
dev/[email protected]/
Thanks,
Amit
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