vmexit_vmcall in ubuntu_kvm_unit_test failed with "Unhandled exception 6 #UD at ip 000000000040024f" with J-realtime on openstack AMD64

[Po-Hsu Lin]

vmexit_vmcall test in ubuntu_kvm_unit_test will fail with J-realtime on openstack amd64 instance. This issue can be seen after we start testing on openstack with 5.15.0-1036.39 in sru-20230320.

Test log:
 Running '/home/ubuntu/autotest/client/tmp/ubuntu_kvm_unit_tests/src/kvm-unit-tests/tests/vmexit_vmcall'
 BUILD_HEAD=d8edb59a
 timeout -k 1s --foreground 90s /usr/bin/qemu-system-x86_64 --no-reboot -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=tcg -kernel /tmp/tmp.JK8g0Sm7qn -smp 1 -append vmcall # -initrd /tmp/tmp.AiLDHJBV6A
 enabling apic
 smp: waiting for 0 APs
 paging enabled
 cr0 = 80010011
 cr3 = 1007000
 cr4 = 20
 pci-testdev at 0x10 membar febff000 iobar c000
 Unhandled exception 6 #UD at ip 000000000040024f
 error_code=0000 rflags=00000202 cs=00000008
 rax=0000000000000000 rcx=0000000000000000 rdx=0000000000400241 rbx=0000000000000000
 rbp=0000000000514b70 rsi=0000000000000000 rdi=0000000000400241
  r8=0000000000000001 r9=000000000040046f r10=000000000000000d r11=0000000000000010
 r12=0000000000400241 r13=000000000040046f r14=0000000000409028 r15=0000000000409028
 cr0=0000000080010011 cr2=0000000000000000 cr3=0000000001007000 cr4=0000000000000020
 cr8=0000000000000000
     STACK: @40024f 40048e 4054b4 4055e7 405618 400f57 40021d
 FAIL vmexit_vmcall

This issue still exist with the latest upstream kvm-unit-tests code (02d8befe99f8)
It's worthy to note that this test has passed with j/ibm on openstack amd64.