debug in ubuntu_kvm_unit_test failed: KVM: entry failed, hardware error since 4.15 (hw-dependent issue)

[Po-Hsu Lin]

Issue found after kvm-unit-test repo updated to d8a4f9e5 (ci: Update the list of tests that we run in the Fedora Cirrus-CI),

This debug test failure is slightly different from the debug failure in 3.13 / 4.4 (bug 1821906)

 Running '/home/ubuntu/autotest/client/tmp/ubuntu_kvm_unit_tests/src/kvm-unit-tests/tests/debug'
 BUILD_HEAD=63cdb04b
 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=kvm -kernel /tmp/tmp.fRLhUpoPu9 -smp 1 # -initrd /tmp/tmp.7MiBbjbPuf
 enabling apic
 smp: waiting for 0 APs
 PASS: DR4==DR6 with CR4.DE == 0
 PASS: DR4 read got #UD with CR4.DE == 1
 PASS: #BP
 PASS: hw breakpoint (test that dr6.BS is not set)
 PASS: hw breakpoint (test that dr6.BS is not cleared)
 PASS: Single-step #DB basic test
 PASS: Usermode Single-step #DB basic test
 PASS: Single-step #DB on emulated instructions
 PASS: Usermode Single-step #DB on emulated instructions
 KVM: entry failed, hardware error 0x80000021

 If you're running a guest on an Intel machine without unrestricted mode
 support, the failure can be most likely due to the guest entering an invalid
 state for Intel VT. For example, the guest maybe running in big real mode
 which is not supported on less recent Intel processors.

 RAX=0000000000000106 RBX=00000000004002ba RCX=00000000000003fd RDX=00000000000003f8
 RSI=0000000000400582 RDI=00000000004002ba RBP=00000000005116e0 RSP=00000000005116e0
 R8 =0000000000410589 R9 =00000000000003f8 R10=000000000000000d R11=0000000000000000
 R12=0000000000400582 R13=0000000000000000 R14=0000000000000000 R15=0000000000000000
 RIP=00000000004002ca RFL=00000306 [-----P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
 ES =0043 0000000000000000 ffffffff 00c0f300 DPL=3 DS [-WA]
 CS =0008 0000000000000000 ffffffff 00a09b00 DPL=0 CS64 [-RA]
 SS =0000 0000000000000000 ffffffff 00c00000
 DS =0043 0000000000000000 ffffffff 00c0f300 DPL=3 DS [-WA]
 FS =0000 0000000000000000 ffffffff 00c01300
 GS =0000 0000000000510740 ffffffff 00c01300
 LDT=0000 0000000000000000 0000ffff 00008200 DPL=0 LDT
 TR =0080 00000000005188c0 0000ffff 00008b00 DPL=0 TSS64-busy
 GDT= 000000000040e100 0000106f
 IDT= 000000000051f060 00000fff
 CR0=80000011 CR2=0000000000000000 CR3=000000000040c000 CR4=00000020
 DR0=0000000000400aa8 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000
 DR6=00000000ffff4ff0 DR7=0000000000000402
 EFER=0000000000000500
 Code=f0 5b 5d c3 55 48 89 e5 fa 9c 58 48 0d 00 01 00 00 50 9d fb <48> 25 ff fe ff ff 50 9d 48 8d 15 f1 ff ff ff 48 89 d0 5d c3 55 48 89 e5 9c 58 48 0d 00 01
 qemu-system-x86_64: terminating on signal 15 from pid 14236
 FAIL debug (timeout; duration=90s)

This looks like a HW-dependent issue, node gonzo with B-4.15 is not failing with this test.

[Roxana Nicolescu (roxanan)]

Found on xenial hwe 4.15.0-211.222~16.04.1