possible bug detaching and reattaching nvme drives

[Oguz Bektas]

Date: Tue, 26 May 2020 16:40:18 +0200
From: Oguz Bektas <o.bektas@proxmox.com>
To: t.lamprecht@proxmox.com
Subject: possible bug detaching and reattaching nvme drives
User-Agent: Mutt/1.10.1 (2018-07-13)

hi list,


i am having a problem with nvme, specifically while doing attach/detach
followed by attach of an nvme device/drive.

basically the VM is running with this commandline on Proxmox VE 6.2:

------
/usr/bin/kvm \
  -id 105 \
  -name kali \
  -chardev 'socket,id=qmp,path=/var/run/qemu-server/105.qmp,server,nowait' \
  -mon 'chardev=qmp,mode=control' \
  -chardev 'socket,id=qmp-event,path=/var/run/qmeventd.sock,reconnect=5' \
  -mon 'chardev=qmp-event,mode=control' \
  -pidfile /var/run/qemu-server/105.pid \
  -daemonize \
  -smbios 'type=1,uuid=fee8e512-7465-4a1d-8361-6acbc423b897' \
  -smp '1,sockets=1,cores=1,maxcpus=1' \
  -nodefaults \
  -boot 
'menu=on,strict=on,reboot-timeout=1000,splash=/usr/share/qemu-server/bootsplash.jpg'
 \
  -vnc unix:/var/run/qemu-server/105.vnc,password \
  -cpu kvm64,enforce,+kvm_pv_eoi,+kvm_pv_unhalt,+lahf_lm,+sep \
  -m 2048 \
  -device 'pci-bridge,id=pci.1,chassis_nr=1,bus=pci.0,addr=0x1e' \
  -device 'pci-bridge,id=pci.2,chassis_nr=2,bus=pci.0,addr=0x1f' \
  -device 'vmgenid,guid=3dde676f-f7da-45d5-b344-66f094845c8a' \
  -device 'piix3-usb-uhci,id=uhci,bus=pci.0,addr=0x1.0x2' \
  -device 'usb-tablet,id=tablet,bus=uhci.0,port=1' \
  -device 'VGA,id=vga,bus=pci.0,addr=0x2' \
  -device 'virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x3' \
  -iscsi 'initiator-name=iqn.1993-08.org.debian:01:c1255109cd2' \
  -drive 
'file=/mnt/pve/nasi/template/iso/kali-linux-2020.1a-installer-amd64.iso,if=none,id=drive-ide2,media=cdrom,aio=threads'
 \
  -device 'ide-cd,bus=ide.1,unit=0,drive=drive-ide2,id=ide2,bootindex=200' \
  -drive 
'file=/dev/pve/vm-105-disk-0,if=none,id=drive-nvme0,format=raw,cache=none,aio=native,detect-zeroes=on'
 \
  -device 'nvme,drive=drive-nvme0,id=nvme0,bootindex=100,serial=nvme0' \
  -netdev 
'type=tap,id=net0,ifname=tap105i0,script=/var/lib/qemu-server/pve-bridge,downscript=/var/lib/qemu-server/pve-bridgedown,vhost=on'
 \
  -device 
'virtio-net-pci,mac=8E:87:65:F4:C6:4F,netdev=net0,bus=pci.0,addr=0x12,id=net0,bootindex=300'
 \
  -machine 'type=pc+pve0'
------

the relevant bits are the following lines:

------
  -drive 
'file=/dev/pve/vm-105-disk-0,if=none,id=drive-nvme0,format=raw,cache=none,aio=native,detect-zeroes=on'
 \
  -device 'nvme,drive=drive-nvme0,id=nvme0,bootindex=100,serial=nvme0' \
------

the nvme emulation is working fine, and hotplugging and hot-unplugging is also 
working. however when i try to detach an existing drive via hmp command, and 
attach it again with the same id (which doesn't exist according to qom-tree and 
qtree after detaching the drive), i'm getting this error:
----
Duplicate ID 'drive-nvme0' for drive
----

this is happening in qemu/util/qemu-option.c on qemu 4.2.0

adding it back with a different id works, so to me it seems like after 
detaching the drive and device from the VM, something stays remnant in the 
memory, making qemu think the drive is still there??

did anyone encounter this before? is this a bug?

if you need any more information please let me know.

regards