On Wed, Apr 26, 2023 at 07:20:08PM +0200, Kashyap Chamarthy wrote: > On Wed, Apr 26, 2023 at 07:40:02PM +0300, Michael Tokarev wrote: > > 18.04.2023 12:04, Igor Mammedov wrote: > > > with Q35 using ACPI PCI hotplug by default, user's request to unplug > > > device is ignored when it's issued before guest OS has been booted. > > > And any additional attempt to request device hot-unplug afterwards > > > results in following error: > > > > > > "Device XYZ is already in the process of unplug" > > > > > > arguably it can be considered as a regression introduced by [2], > > > before which it was possible to issue unplug request multiple > > > times. > > > > Stable-8.0 material? > > FWIW, I'd say, yes. This fix is useful for stable releases. As this > solves a real problem for upper-management tools. > > I have tested this fix; and it works. I'll post my testing notes / > reproducer in a follow-up email. In short, I followed the > reproducer steps from here[1].
Tested-by: Kashyap Chamarthy <kcham...@redhat.com> It solves the device-detach bug noted here[1]. As promised, here are my reproducer notes (expanded from[1]): Disk image prep --------------- (1) Download an Ubuntu "Jammy" guest image from here: https://cloud-images.ubuntu.com/jammy/current/jammy-server-cloudimg-amd64.img (2) Update the above disk image's kernel command-line to have the guest-boot slowed down by 100 seconds; use "boot_delay=100". (3) Have an additional image ("disk2.img") ready for hot-plug/un-plug. Test ---- (1) Build QEMU with the patch in question: $ git describe 7.2.94v8.0.0-rc4-1-gfa6650df6d7 (2) Use the above QEMU binary to launch the Ubuntu "Jammy" guest: $ virsh dumpxml jammy1 | grep emulator <emulator>/home/kashyapc/tinker-space/qemu-upstream/build/qemu-system-x86_64</emulator> (3) Have a split `tmux` ready; start the guest in the first pane, with the serial console logs rolling: $ virsh start jammy1 --console (4) Wait until the guest consoles messages start rolling. Once they do, on the other `tmux` pane, issue the below command (it's a live attach, followed by a detach): $ virsh attach-disk jammy1 ./disk2.img vdb --live --persistent \ && sleep 1 \ && virsh detach-disk jammy1 --live ./disk2.img Disk attached successfully Disk detached successfully (5) Enumerate the attached block devices to the guest. We still see the second disk, "disk2.img": $> virsh domblklist jammy1 Target Source ------------------------------------------- vda /data/images/jammy-ubuntu.qcow2 vdb /data/images/disk2.img (6) Now detach the disk from the inactive guest XML (that affects next boot) by using "--persistent" flag; and enumerate the live block devices (we still see the second disk) $> virsh detach-disk jammy1 --persistent /data/images/disk2.img Disk detached successfully $> virsh domblklist jammy1 Target Source ------------------------------------------- vda /data/images/jammy-ubuntu.qcow2 vdb /data/images/disk2.img (NOTE: We're using two separate calls to `virsh detach-disk`, one with "--live" and the other with "--persistent" based on upstream libvirt recommendation in [1].) (7) Again, re-issue the detach command with just "--live" flag: $> virsh detach-disk jammy1 --live /data/images/disk2.img Disk detached successfully (8) Re-enumerate the attached block devices: $> virsh domblklist jammy1 Target Source ------------------------------------------- vda /data/images/jammy-ubuntu.qcow2 Now we see the second device is detached "for real". Overall, we were able to successfully re-issue `device detach` while the guest is still booting, and see through the actual detach to its logical conclusion. [1] https://gitlab.com/libvirt/libvirt/-/issues/309 -- Disk detach is unsuccessfull while the guest is still booting -- /kashyap