[Qemu-devel] efi var store migration assert (bdrv_co_do_pwritev: Assertion `!(bs->open_flags & 0x0800)' failed.)

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

In the continuing journeys of trying to migrate a q35 guest with ovmf,
I've just hit this assert:

qemu-system-x86_64: /root/git/qemu/block/io.c:1297: bdrv_co_do_pwritev: Assertion `!(bs->open_flags & 0x0800)' failed.

This is just ahead of rc0 - 1458317c8ada834cf39287f6d11a8cb8a37360d6 from yesterday.

It looks like that's the efi var store stuff:

#4  0x00007f8073ec3947 in bdrv_co_do_pwritev (bs=0x7f8074faf580, offset=<optimized out>, bytes=131072, 
    qiov=0x7f805d5feb50, flags=(unknown: 0)) at /root/git/qemu/block/io.c:1297
#5  0x00007f8073eb6846 in blk_co_pwritev (blk=<optimized out>, offset=<optimized out>, bytes=<optimized out>, 
    qiov=<optimized out>, flags=<optimized out>) at /root/git/qemu/block/block-backend.c:713
#6  0x00007f8073eb688c in blk_write_entry (opaque=0x7f805d5feb70) at /root/git/qemu/block/block-backend.c:736
#7  0x00007f8073f2782a in coroutine_trampoline (i0=<optimized out>, i1=<optimized out>)
    at /root/git/qemu/util/coroutine-ucontext.c:78
#8  0x00007f806aff9110 in ?? () from /lib64/libc.so.6
#9  0x00007f805d5fe3c0 in ?? ()
#10 0x0000000000000000 in ?? ()
(gdb) up
#1  0x00007f806afe8ce8 in abort () from /lib64/libc.so.6
(gdb) 
#2  0x00007f806afe0566 in __assert_fail_base () from /lib64/libc.so.6
(gdb) 
#3  0x00007f806afe0612 in __assert_fail () from /lib64/libc.so.6
(gdb) 
#4  0x00007f8073ec3947 in bdrv_co_do_pwritev (bs=0x7f8074faf580, offset=<optimized out>, bytes=131072, 
    qiov=0x7f805d5feb50, flags=(unknown: 0)) at /root/git/qemu/block/io.c:1297
1297	    bool use_local_qiov = false;
(gdb) p *bs
$1 = {total_sectors = 256, read_only = 0, open_flags = 10242, encrypted = 0, valid_key = 0, sg = 0, 
  copy_on_read = 0, probed = false, drv = 0x7f8074474840 <bdrv_raw>, opaque = 0x0, blk = 0x7f8074fa5920, 
  aio_context = 0x7f8074f61bd0, aio_notifiers = {lh_first = 0x0}, 
  filename = "/var/lib/libvirt/qemu/nvram/f23q35efi_VARS.fd", '\000' <repeats 4040 times>, 
  backing_file = '\000' <repeats 4095 times>, backing_format = '\000' <repeats 15 times>, 
  full_open_options = 0x7f8074fb9b60, 
  exact_filename = "/var/lib/libvirt/qemu/nvram/f23q35efi_VARS.fd", '\000' <repeats 4040 times>, 
  backing = 0x0, file = 0x7f8074fa6020, before_write_notifiers = {notifiers = {lh_first = 0x0}}, 
  serialising_in_flight = 0, throttled_reqs = {{entries = {tqh_first = 0x0, tqh_last = 0x7f8074fb2608}}, {
      entries = {tqh_first = 0x0, tqh_last = 0x7f8074fb2618}}}, io_limits_enabled = false, throttle_state = 0x0, 
  throttle_timers = {timers = {0x0, 0x0}, clock_type = QEMU_CLOCK_REALTIME, read_timer_cb = 0x0, 
    write_timer_cb = 0x0, timer_opaque = 0x0}, pending_reqs = {0, 0}, round_robin = {le_next = 0x0, 
    le_prev = 0x0}, wr_highest_offset = 0, bl = {max_discard = 0, discard_alignment = 0, max_write_zeroes = 0, 
    write_zeroes_alignment = 0, opt_transfer_length = 0, max_transfer_length = 0, min_mem_alignment = 1, 
    opt_mem_alignment = 4096, max_iov = 1024}, zero_beyond_eof = true, request_alignment = 512, 
  node_name = "#block307", '\000' <repeats 22 times>, node_list = {tqe_next = 0x7f8074fc1eb0, 
    tqe_prev = 0x7f8074fb8a00}, bs_list = {tqe_next = 0x7f8074fb5890, tqe_prev = 0x7f8074faa9a0}, monitor_list = {
    tqe_next = 0x0, tqe_prev = 0x0}, dirty_bitmaps = {lh_first = 0x0}, refcnt = 1, tracked_requests = {
    lh_first = 0x0}, op_blockers = {{lh_first = 0x0} <repeats 16 times>}, job = 0x0, inherits_from = 0x0, 
  children = {lh_first = 0x7f8074fa6020}, parents = {lh_first = 0x7f8074fa5a80}, options = 0x7f8074fa04f0, 
  explicit_options = 0x7f8074fb2830, detect_zeroes = BLOCKDEV_DETECT_ZEROES_OPTIONS_OFF, backing_blocker = 0x0, 
  write_threshold_offset = 0, write_threshold_notifier = {notify = 0x0, node = {le_next = 0x0, le_prev = 0x0}}, 
  quiesce_counter = 0}

Full command line:
/opt/qemu-head/bin/qemu-system-x86_64 -name f23q35efib -S -machine pc-q35-2.6,accel=kvm,usb=off,vmport=off -cpu SandyBridge -drive file=/usr/share/OVMF/OVMF_CODE.fd,if=pflash,format=raw,unit=0,readonly=on -drive file=/var/lib/libvirt/qemu/nvram/f23q35efi.fd,if=pflash,format=raw,unit=1 -m 4096 -realtime mlock=off -smp 4,sockets=4,cores=1,threads=1 -uuid e938e303-0cff-4863-9a0b-cf7bcca2f532 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-2-f23q35efib/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew -global kvm-pit.lost_tick_policy=discard -no-hpet -no-shutdown -global ICH9-LPC.disable_s3=1 -global ICH9-LPC.disable_s4=1 -boot strict=on -device pci-bridge,chassis_nr=1,id=pci.1,bus=pcie.0,addr=0x1e -device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x1 -device ich9-usb-ehci1,id=usb,bus=pcie.0,addr=0x1d.0x7 -device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pcie.0,multifunction=on,addr=0x1d -device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pcie.0,addr=0x1d.0x1 -device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pcie.0,addr=0x1d.0x2 -device lsi,id=scsi0,bus=pci.2,addr=0x6 -device virtio-serial-pci,id=virtio-serial0,bus=pci.2,addr=0x3 -drive file=/home/vms/f23q35efi.qcow2,format=qcow2,if=none,id=drive-virtio-disk0,cache=none -device virtio-blk-pci,scsi=off,bus=pci.2,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive if=none,id=drive-scsi0-0-0,readonly=on -device scsi-cd,bus=scsi0.0,scsi-id=0,drive=drive-scsi0-0-0,id=scsi0-0-0,bootindex=2 -netdev tap,fd=25,id=hostnet0 -device e1000,netdev=hostnet0,id=net0,mac=52:54:00:1f:62:58,bus=pci.2,addr=0x1 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev socket,id=charchannel0,path=/var/lib/libvirt/qemu/channel/target/domain-2-f23q35efib/org.qemu.guest_agent.0,server,nowait -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=org.qemu.guest_agent.0 -chardev spicevmc,id=charchannel1,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel1,id=channel1,name=com.redhat.spice.0 -device usb-tablet,id=input0 -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,bus=pcie.0,addr=0x1 -device intel-hda,id=sound0,bus=pci.2,addr=0x2 -device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -chardev spicevmc,id=charredir0,name=usbredir -device usb-redir,chardev=charredir0,id=redir0 -chardev spicevmc,id=charredir1,name=usbredir -device usb-redir,chardev=charredir1,id=redir1 -device virtio-balloon-pci,id=balloon0,bus=pci.2,addr=0x5 -msg timestamp=on

--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK