Description of problem:

when we boot rhel7 guest 261 virtio-scsi disk to guest, guest only detect 26 disk; but if we set lun ID discontinuous (with stepping 63) only fist disk detect in guest;
 

Version-Release number of selected component (if applicable):

qemu-kvm-1.5.0-2.el7.x86_64

How reproducible:

100%

Steps to Reproduce:
1. create 1M qcow2 image file

for i in `seq 0 260`;do qemu-img create -f "/tmp/stg$i.qcow2" 1M; done


2. boot guest with cmd in attachment:
    /usr/libexec/qemu-kvm \
    -name 'virt-tests-vm1' \
    -nodefaults \
    -chardev socket,id=qmp_id_qmpmonitor1,path=/tmp/monitor-qmpmonitor1-20130827-183340-iDVccT9c,server,nowait \
    -mon chardev=qmp_id_qmpmonitor1,mode=control \
    -chardev socket,id=serial_id_serial1,path=/tmp/serial-serial1-20130827-183340-iDVccT9c,server,nowait \
    -device isa-serial,chardev=serial_id_serial1 \
    -chardev socket,id=seabioslog_id_20130827-183340-iDVccT9c,path=/tmp/seabios-20130827-183340-iDVccT9c,server,nowait \
    -device isa-debugcon,chardev=seabioslog_id_20130827-183340-iDVccT9c,iobase=0x402 \
    -device ich9-usb-uhci1,id=usb1,bus=pci.0,addr=0x4 \
    -drive file='/root/test/autotest-devel/client/tests/virt/shared/data/images/RHEL-Server-6.3-64-virtio.qcow2',index=0,if=none,id=drive-virtio-disk1,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device virtio-blk-pci,bus=pci.0,addr=0x5,drive=drive-virtio-disk1,bootindex=0 \
    -device virtio-scsi-pci,id=virtio_scsi_pci0,addr=0x6 \
    -drive file='/tmp/stg0.qcow2',if=none,id=virtio-scsi2-id0,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=0,drive=virtio-scsi2-id0 \
    -drive file='/tmp/stg1.qcow2',if=none,id=virtio-scsi3-id1,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=63,drive=virtio-scsi3-id1 \
    -drive file='/tmp/stg2.qcow2',if=none,id=virtio-scsi4-id2,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=126,drive=virtio-scsi4-id2 \
    -drive file='/tmp/stg3.qcow2',if=none,id=virtio-scsi5-id3,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=189,drive=virtio-scsi5-id3 \
    -drive file='/tmp/stg4.qcow2',if=none,id=virtio-scsi6-id4,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=252,drive=virtio-scsi6-id4 \
    -drive file='/tmp/stg5.qcow2',if=none,id=virtio-scsi7-id5,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=315,drive=virtio-scsi7-id5 \
    -drive file='/tmp/stg6.qcow2',if=none,id=virtio-scsi8-id6,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=378,drive=virtio-scsi8-id6 \
    -drive file='/tmp/stg7.qcow2',if=none,id=virtio-scsi9-id7,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=441,drive=virtio-scsi9-id7 \
    -drive file='/tmp/stg8.qcow2',if=none,id=virtio-scsi10-id8,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=504,drive=virtio-scsi10-id8 \
    -drive file='/tmp/stg9.qcow2',if=none,id=virtio-scsi11-id9,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=567,drive=virtio-scsi11-id9 \
    -drive file='/tmp/stg10.qcow2',if=none,id=virtio-scsi12-id10,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    ...
    -drive file='/tmp/stg236.qcow2',if=none,id=virtio-scsi238-id236,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=14868,drive=virtio-scsi238-id236 \
    -drive file='/tmp/stg237.qcow2',if=none,id=virtio-scsi239-id237,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=14931,drive=virtio-scsi239-id237 \
    -drive file='/tmp/stg238.qcow2',if=none,id=virtio-scsi240-id238,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=14994,drive=virtio-scsi240-id238 \
    -drive file='/tmp/stg239.qcow2',if=none,id=virtio-scsi241-id239,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15057,drive=virtio-scsi241-id239 \
    -drive file='/tmp/stg240.qcow2',if=none,id=virtio-scsi242-id240,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15120,drive=virtio-scsi242-id240 \
    -drive file='/tmp/stg241.qcow2',if=none,id=virtio-scsi243-id241,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15183,drive=virtio-scsi243-id241 \
    -drive file='/tmp/stg242.qcow2',if=none,id=virtio-scsi244-id242,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15246,drive=virtio-scsi244-id242 \
    -drive file='/tmp/stg243.qcow2',if=none,id=virtio-scsi245-id243,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15309,drive=virtio-scsi245-id243 \
    -drive file='/tmp/stg244.qcow2',if=none,id=virtio-scsi246-id244,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15372,drive=virtio-scsi246-id244 \
    -drive file='/tmp/stg245.qcow2',if=none,id=virtio-scsi247-id245,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15435,drive=virtio-scsi247-id245 \
    -drive file='/tmp/stg246.qcow2',if=none,id=virtio-scsi248-id246,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15498,drive=virtio-scsi248-id246 \
    -drive file='/tmp/stg247.qcow2',if=none,id=virtio-scsi249-id247,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15561,drive=virtio-scsi249-id247 \
    -drive file='/tmp/stg248.qcow2',if=none,id=virtio-scsi250-id248,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15624,drive=virtio-scsi250-id248 \
    -drive file='/tmp/stg249.qcow2',if=none,id=virtio-scsi251-id249,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15687,drive=virtio-scsi251-id249 \
    -drive file='/tmp/stg250.qcow2',if=none,id=virtio-scsi252-id250,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15750,drive=virtio-scsi252-id250 \
    -drive file='/tmp/stg251.qcow2',if=none,id=virtio-scsi253-id251,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15813,drive=virtio-scsi253-id251 \
    -drive file='/tmp/stg252.qcow2',if=none,id=virtio-scsi254-id252,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15876,drive=virtio-scsi254-id252 \
    -drive file='/tmp/stg253.qcow2',if=none,id=virtio-scsi255-id253,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=15939,drive=virtio-scsi255-id253 \
    -drive file='/tmp/stg254.qcow2',if=none,id=virtio-scsi256-id254,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=16002,drive=virtio-scsi256-id254 \
    -drive file='/tmp/stg255.qcow2',if=none,id=virtio-scsi257-id255,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=16065,drive=virtio-scsi257-id255 \
    -drive file='/tmp/stg256.qcow2',if=none,id=virtio-scsi258-id256,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=16128,drive=virtio-scsi258-id256 \
    -drive file='/tmp/stg257.qcow2',if=none,id=virtio-scsi259-id257,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=16191,drive=virtio-scsi259-id257 \
    -drive file='/tmp/stg258.qcow2',if=none,id=virtio-scsi260-id258,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=16254,drive=virtio-scsi260-id258 \
    -drive file='/tmp/stg259.qcow2',if=none,id=virtio-scsi261-id259,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=16317,drive=virtio-scsi261-id259 \
    -drive file='/tmp/stg260.qcow2',if=none,id=virtio-scsi262-id260,media=disk,cache=unsafe,snapshot=off,format=qcow2,aio=native \
    -device scsi-disk,lun=16380,drive=virtio-scsi262-id260 \
    -m 4096 \
    -smp 4,maxcpus=4,cores=2,threads=1,sockets=2 \
    -cpu 'SandyBridge' \
    -M pc \
    -device usb-tablet,id=usb-tablet1,bus=usb1.0,port=1 \
    -vnc :0 \
    -vga cirrus \
    -rtc base=utc,clock=host,driftfix=slew  \
    -boot order=cdn,once=c,menu=off   \
    -no-kvm-pit-reinjection \
    -enable-kvm \
    -monitor stdio


3. login guest to check all disk detected


ls -l /dev/sd*

Actual results:

only 1 scsi disk listed, if changed lun ID increase stepping to 128, 26 disk can be listed in guest;

Expected results:

all 260 disk should be list in guest

Additional info:

see info qtree output in attachment;

test with rhel6.3/ rhel6.4 and rhel7.0 guest met the same issue