Verified it on qemu-kvm-4.1.0-10.module+el8.1.0+4234+33aa4f57.x86_64, the solution has taken effect, set bug's status to "Verified".

Test steps:
  1.Start guest with qemu cmds:
          -name 'avocado-vt-vm1' \
    -machine q35  \
    -nodefaults \
    -device VGA,bus=pcie.0,addr=0x1  \
    -chardev socket,id=qmp_id_qmpmonitor1,path=/var/tmp/monitor-qmpmonitor1-20190820-032540-OesJUJdj,server,nowait \
    -mon chardev=qmp_id_qmpmonitor1,mode=control  \
    -chardev socket,id=qmp_id_catch_monitor,path=/var/tmp/monitor-catch_monitor-20190820-032540-OesJUJdj,server,nowait \
    -mon chardev=qmp_id_catch_monitor,mode=control \
    -device pvpanic,ioport=0x505,id=idbJPqrG \
    -chardev socket,id=chardev_serial0,server,path=/var/tmp/serial-serial0-20190820-032540-OesJUJdj,nowait \
    -device isa-serial,id=serial0,chardev=chardev_serial0  \
    -chardev socket,id=seabioslog_id_20190820-032540-OesJUJdj,path=/var/tmp/seabios-20190820-032540-OesJUJdj,server,nowait \
    -device isa-debugcon,chardev=seabioslog_id_20190820-032540-OesJUJdj,iobase=0x402 \
    -device pcie-root-port,id=pcie.0-root-port-2,slot=2,chassis=2,addr=0x2,bus=pcie.0 \
    -device qemu-xhci,id=usb1,bus=pcie.0-root-port-2,addr=0x0 \
    -object iothread,id=iothread0 \
    -device pcie-root-port,id=pcie.0-root-port-3,slot=3,chassis=3,addr=0x3,bus=pcie.0 \
    -blockdev driver=file,node-name=file_node,filename=/home/kvm_autotest_root/images/rhel810-64-virtio.qcow2 \
    -blockdev driver=qcow2,file=file_node,node-name=drive_image1 \
    -device virtio-blk-pci,id=image1,drive=drive_image1,bootindex=0,bus=pcie.0-root-port-3,addr=0x0 \
    -device pcie-root-port,id=pcie.0-root-port-7,slot=7,chassis=7,addr=0x7,bus=pcie.0 \
    -device pcie-root-port,id=pcie.0-root-port-4,slot=4,chassis=4,addr=0x4,bus=pcie.0 \
    -device virtio-net-pci,mac=9a:19:6a:3c:a6:a5,id=idq14C2Q,netdev=idHzG7Zk,bus=pcie.0-root-port-4,addr=0x0  \
    -netdev tap,id=idHzG7Zk,vhost=on \
    -m 2048  \
    -smp 4,maxcpus=4,cores=2,threads=1,sockets=2  \
    -cpu 'Skylake-Client',+kvm_pv_unhalt \
    -device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1  \
    -vnc :0  \

 2.Create a node with driver "nfs"
   {'execute':'blockdev-create','arguments':{'options': {'driver':'nfs','size':32212254720,'location':{'path':'/mnt/nfs','server':{'host':'10.66.8.210','type':'inet'}}},'job-id':'j1'}}
  {"error": {"class": "GenericError", "desc": "Block driver 'nfs' not found or not supported"}}

 So, when nfs is not supported in blockdev-create, qemu just report the error and won't coredump.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2019:3723