Today while working with two different Windows Server 2012 R2 guests I found that when I try to attach an ISO file to a SCSI CD-ROM device through libvirt (virsh or virt-manager) while the guest is running, qemu crashes and the following message is logged:
Assertion failed: blk_get_aio_context(d->conf.blk) == s->ctx (/home/buildozer/aports/main/qemu/src/qemu-4.0.0/hw/scsi/virtio-scsi.c: virtio_scsi_ctx_check: 246)
I can repro this at will. All I have to do is to try to attach an ISO file to the SCSI CDROM while the guest is running.
The SCSI controller model is virtio-scsi with iothread enabled.
Please find below all the details about my setup that I considered relevant but I missed something please don't hesitate to let me know:
Host arch: x86_64
Distro: Alpine Linux 3.10.2
qemu version: 4.0
Linux kernel version: 4.19.67
libvirt: 5.5.0
Emulated SCSI controller: virtio-scsi (with iothread enabled)
Guest firmware: OVMF-EFI
Guest OS: Window Server 2012 R2
Guest virtio drivers version: 171 (current stable)
qemu command line:
/usr/bin/qemu-system-x86_64 -name guest=DCHOMENET01,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-78-DCHOMENET01/master-key.aes -machine pc-i440fx-4.0,accel=kvm,usb=off,dump-guest-core=on -cpu IvyBridge,ss=on,vmx=off,pcid=on,hypervisor=on,arat=on,tsc_adjust=on,umip=on,xsaveopt=on,hv_time,hv_relaxed,hv_vapic,hv_spinlocks=0x1fff
-drive file=/usr/share/edk2.git/ovmf-x64/OVMF_CODE-pure-efi.fd,if=pflash,format=raw,unit=0,readonly=on -drive file=/var/lib/libvirt/qemu/nvram/DCHOMENET01_VARS.fd,if=pflash,format=raw,unit=1 -m 1536 -overcommit mem-lock=off -smp 1,sockets=1,cores=1,threads=1
-object iothread,id=iothread1 -uuid f06978ad-2734-44ab-a518-5dfcf71d625e -no-user-config -nodefaults -chardev socket,id=charmonitor,fd=33,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime,driftfix=slew -global kvm-pit.lost_tick_policy=delay
-no-hpet -no-shutdown -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1 -boot strict=on -device qemu-xhci,id=usb,bus=pci.0,addr=0x4 -device virtio-scsi-pci,iothread=iothread1,id=scsi0,num_queues=1,bus=pci.0,addr=0x5 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6
-drive file=/storage/storage-hdd-vms/virtual_machines_hdd/dchomenet01.qcow2,format=qcow2,if=none,id=drive-scsi0-0-0-0,cache=none,discard=unmap,aio=threads -device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,device_id=drive-scsi0-0-0-0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=1,write-cache=on
-drive if=none,id=drive-scsi0-0-0-1,readonly=on -device scsi-cd,bus=scsi0.0,channel=0,scsi-id=0,lun=1,device_id=drive-scsi0-0-0-1,drive=drive-scsi0-0-0-1,id=scsi0-0-0-1 -netdev tap,fd=41,id=hostnet0,vhost=on,vhostfd=43 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:99:b5:62,bus=pci.0,addr=0x3
-chardev socket,id=charserial0,host=127.0.0.1,port=4900,telnet,server,nowait -device isa-serial,chardev=charserial0,id=serial0 -chardev spicevmc,id=charchannel0,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0
-chardev socket,id=charchannel1,fd=45,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel1,id=channel1,name=org.qemu.guest_agent.0 -chardev spiceport,id=charchannel2,name=org.spice-space.webdav.0 -device virtserialport,bus=virtio-serial0.0,nr=3,chardev=charchannel2,id=channel2,name=org.spice-space.webdav.0
-device virtio-tablet-pci,id=input2,bus=pci.0,addr=0x7 -spice port=5900,addr=127.0.0.1,disable-ticketing,seamless-migration=on -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,max_outputs=1,bus=pci.0,addr=0x2 -chardev
spicevmc,id=charredir0,name=usbredir -device usb-redir,chardev=charredir0,id=redir0,bus=usb.0,port=2 -chardev spicevmc,id=charredir1,name=usbredir -device usb-redir,chardev=charredir1,id=redir1,bus=usb.0,port=3 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x8
-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny -msg timestamp=on
I can provide a core dump of the process if needed for debugging and the guest XML as well.
Thanks.
Fernando