Description of problem:
Could not access KVM kernel module and qemu-kvm: failed to initialize KVM when boot L2 guest. Only occured when boot L1 guest with -cpu $module_name,vmx


Version-Release number of selected component (if applicable):
host info:
(1)cpu info
[root@dhcp-12-148 qemu-sh]# virsh capabilities | grep model
      <model>IvyBridge-IBRS</model>
    <secmodel>
      <model>selinux</model>
    </secmodel>
    <secmodel>
      <model>dac</model>
    </secmodel>
(2)version info:
kernel-4.18.0-103.el8.x86_64 & qemu-img-4.0.0-4.module+el8.1.0+3356+cda7f1ee.x86_64

guest info:
kernel-4.18.0-100.el8.x86_64 & qemu-img-4.0.0-4.module+el8.1.0+3356+cda7f1ee.x86_64


How reproducible:
5/5


Steps to Reproduce:
1.enable nested on L0 host:
[root@dhcp-12-148 ~]# cat /sys/module/kvm_intel/parameters/nested
Y
2.boot L1 guest with commands on L0:
/usr/libexec/qemu-kvm \
-enable-kvm \
-machine q35  \
-m 4096 \
-smp 2 \
-cpu "Nehalem",vmx \
-device pcie-root-port,id=pcie.0-root-port-2,slot=2,chassis=2,addr=0x2,bus=pcie.0 \
-device pcie-root-port,id=pcie.0-root-port-3,slot=3,chassis=3,addr=0x3,bus=pcie.0 \
-device pcie-root-port,id=pcie.0-root-port-4,slot=4,chassis=4,addr=0x4,bus=pcie.0 \
-blockdev node-name=back_image,driver=file,cache.direct=on,cache.no-flush=off,filename=/mnt/nfs/rhel8-1-0-blk.qcow2,aio=threads \
-blockdev node-name=drive-virtio-disk0,driver=qcow2,cache.direct=on,cache.no-flush=off,file=back_image \
-device virtio-blk-pci,drive=drive-virtio-disk0,id=disk0,bus=pcie.0-root-port-2 \
-netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown,queues=4 \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:1b:21:7a:76:1c,bus=pcie.0-root-port-3,vectors=10,mq=on \
-vnc :0 \
-device VGA \
-monitor stdio \
-qmp tcp:0:1234,server,nowait \
3.in L1 guest, install qemu-kvm and config switch network.
4.boot L2 guest in L1 with commands:
/usr/libexec/qemu-kvm \
-enable-kvm \
-machine q35  \
-m 4096 \
-smp 2 \
-cpu "Nehalem",vmx \
-device pcie-root-port,id=pcie.0-root-port-2,slot=2,chassis=2,addr=0x2,bus=pcie.0 \
-device pcie-root-port,id=pcie.0-root-port-3,slot=3,chassis=3,addr=0x3,bus=pcie.0 \
-device pcie-root-port,id=pcie.0-root-port-4,slot=4,chassis=4,addr=0x4,bus=pcie.0 \
-blockdev node-name=back_image,driver=file,cache.direct=on,cache.no-flush=off,filename=rhel8-1-0-blk.qcow2,aio=threads \
-blockdev node-name=drive-virtio-disk0,driver=qcow2,cache.direct=on,cache.no-flush=off,file=back_image \
-device virtio-blk-pci,drive=drive-virtio-disk0,id=disk0,bus=pcie.0-root-port-2 \
-netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup,downscript=/etc/qemu-ifdown,queues=4 \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:1b:21:7a:76:e1,bus=pcie.0-root-port-3,vectors=10,mq=on \
-vnc :0 \
-device VGA \
-monitor stdio \
-qmp tcp:0:1234,server,nowait \


Actual results:
when execute step4, qemu couldn't start, get error prompts:
Could not access KVM kernel module: No such file or directory
qemu-kvm: failed to initialize KVM: No such file or directory

and found kvm module loaded in L1 failed:
[root@dhcp-12-206 work]# lsmod | grep kvm
kvm                   749568  0
irqbypass              16384  1 kvm


Expected results:
L2 guest could start successfully in L1.


Additional info:
1.when boot L1 with "-cpu host", L2 guest could start successfully in L1, and kvm module loaded succeeded.
2.test on the latest rhel7.7 host using same guest rhel8.1, L2 guest started successfully in L1.