Bug 218255 - Hot-adding SCSI disk in QEMU VM fails
Summary: Hot-adding SCSI disk in QEMU VM fails
Status: NEW
Alias: None
Product: Drivers
Classification: Unclassified
Component: PCI (show other bugs)
Hardware: All Linux
: P3 high
Assignee: drivers_pci@kernel-bugs.osdl.org
URL: https://lore.kernel.org/r/9eb669c0-d8...
Keywords:
Depends on:
Blocks:
 
Reported: 2023-12-11 16:12 UTC by Bjorn Helgaas
Modified: 2023-12-12 20:57 UTC (History)
3 users (show)

See Also:
Kernel Version: v6.5
Subsystem:
Regression: Yes
Bisected commit-id: cc22522fd55e2 ("PCI: acpiphp: Use pci_assign_unassigned_bridge_resources() only for non-root bus")


Attachments
v6.7.0-rc3 dmesg log, fails (54.42 KB, text/plain)
2023-12-11 16:17 UTC, Bjorn Helgaas
Details
v6.7.0-rc3+reverts dmesg log, works (54.20 KB, text/plain)
2023-12-12 09:30 UTC, Fiona Ebner
Details
v6.7.0-rc3 dmesg log, works (54.25 KB, text/plain)
2023-12-12 09:37 UTC, Fiona Ebner
Details

Description Bjorn Helgaas 2023-12-11 16:12:28 UTC
Fiona Ebner <f.ebner@proxmox.com> reported that "hot-plugging SCSI disks for QEMU virtual machines booting with UEFI and with guest kernels >= 6.5 might be broken. It's not consistently broken, hinting there might be a race somewhere."

Reverting the following two commits seems to make it work reliably again:

cc22522fd55e2 ("PCI: acpiphp: Use pci_assign_unassigned_bridge_resources() only for non-root bus")
40613da52b13f ("PCI: acpiphp: Reassign resources on bridge if necessary"
Comment 2 Fiona Ebner 2023-12-12 09:30:10 UTC
Created attachment 305592 [details]
v6.7.0-rc3+reverts dmesg log, works
Comment 3 Fiona Ebner 2023-12-12 09:37:57 UTC
Created attachment 305593 [details]
v6.7.0-rc3 dmesg log, works

The problem does not happen consistently, but it is racy. This is for a run without the reverts where the issue didn't trigger by chance.
Comment 4 Dongli Zhang 2023-12-12 20:57:19 UTC
There is another report.

[Regression report] commit 40613da52b13 ("PCI: acpiphp: Reassign resources on bridge if necessary")

https://lore.kernel.org/all/3c4a446a-b167-11b8-f36f-d3c1b49b42e9@oracle.com/

Thank you very much!

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