ioapic in ubuntu_kvm_unit_test timeout with test_ioapic_logical_destination_mode with J-realtime on openstack AMD64

[Po-Hsu Lin]

ioapic 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/ioapic'
 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.tKzQVFGUKb -smp 4 -cpu qemu64,+x2apic # -initrd /tmp/tmp.uafjlRQFEN
 qemu-system-x86_64: warning: TCG doesn't support requested feature: CPUID.01H:ECX.x2apic [bit 21]
 qemu-system-x86_64: warning: TCG doesn't support requested feature: CPUID.01H:ECX.x2apic [bit 21]
 qemu-system-x86_64: warning: TCG doesn't support requested feature: CPUID.01H:ECX.x2apic [bit 21]
 qemu-system-x86_64: warning: TCG doesn't support requested feature: CPUID.01H:ECX.x2apic [bit 21]
 enabling apic
 enabling apic
 setup: CPU 2 online
 enabling apic
 setup: CPU 1 online
 enabling apic
 setup: CPU 3 online
 smp: waiting for 3 APs
 paging enabled
 cr0 = 80010011
 cr3 = 1007000
 cr4 = 20
 x2apic not detected
 PASS: version register read only test
 PASS: id register only bits [24:27] writable
 PASS: arbitration register set by id
 PASS: arbtration register read only
 PASS: edge triggered intr
 PASS: level triggered intr
 PASS: ioapic simultaneous edge interrupts
 PASS: coalesce simultaneous level interrupts
 PASS: sequential level interrupts
 PASS: retriggered level interrupts without masking
 PASS: masked level interrupt
 PASS: unmasked level interrupt
 PASS: masked level interrupt
 PASS: unmasked level interrupt
 PASS: retriggered level interrupts with mask
 PASS: TMR for ioapic edge interrupts (expected false)
 PASS: TMR for ioapic level interrupts (expected false)
 PASS: TMR for ioapic level interrupts (expected true)
 PASS: TMR for ioapic edge interrupts (expected true)
 PASS: ioapic physical destination mode
 qemu-system-x86_64: terminating on signal 15 from pid 12461 (timeout)
 FAIL ioapic (timeout; duration=90s)

This issue still exist with the latest upstream kvm-unit-tests code (02d8befe99f8)

The test can finish with the test_ioapic_logical_destination_mode() related code commented out. One odd thing is that the test will be triggered here:
  if (cpu_count() > 3)
    test_ioapic_logical_destination_mode();

cpu_count() here will get 4 on this openstack VM, however lscpu shows:
$ lscpu
Architecture: x86_64
  CPU op-mode(s): 32-bit, 64-bit
  Address sizes: 40 bits physical, 48 bits virtual
  Byte Order: Little Endian
CPU(s): 2
  On-line CPU(s) list: 0,1
Vendor ID: AuthenticAMD
  Model name: AMD EPYC-Rome Processor
    CPU family: 23
    Model: 49
    Thread(s) per core: 1
    Core(s) per socket: 1
    Socket(s): 2

We will need to know how cpu_count() got 4 in this case.

It's worthy to note that this test has passed with j/ibm on openstack amd64.