Comment 0 for bug 1882671

The version of QEMU (4.2.0) packaged for Ubuntu 20.04 hangs indefinitely at boot if an OVMF bios is used. This happens ONLY with qemu-system-x86_64. qemu-system-i386 works fine with the latest ia32 OVMF bios.

NOTE[1]: the same identical OVMF bios works fine on QEMU 2.x packaged with Ubuntu 18.04.
NOTE[2]: reproducing the fatal bug requires *no* operating system:

   qemu-system-x86_64 -bios OVMF-pure-efi.fd

On its window QEMU gets stuck at the very first stage:
   "Guest has not initialized the display (yet)."

NOTE[3]: QEMU gets stuck no matter if KVM is used or not.

NOTE[4]: By adding the `-d int` option it is possible to observe that QEMU is, apparently, stuck in an endless loop of interrupts. For the first few seconds, registers' values vary quickly, but at some point they reach a final value, while the interrupt counter increments:

  2568: v=68 e=0000 i=0 cpl=0 IP=0038:0000000007f1d225 pc=0000000007f1d225 SP=0030:0000000007f0c8d0 env->regs[R_EAX]=0000000000000000
RAX=0000000000000000 RBX=0000000007f0c920 RCX=0000000000000000 RDX=0000000000000001
RSI=0000000006d18798 RDI=0000000000008664 RBP=0000000000000000 RSP=0000000007f0c8d0
R8 =0000000000000001 R9 =0000000000000089 R10=0000000000000000 R11=0000000007f2c987
R12=0000000000000000 R13=0000000000000000 R14=0000000007087901 R15=0000000000000000
RIP=0000000007f1d225 RFL=00000246 [---Z-P-] CPL=0 II=0 A20=1 SMM=0 HLT=0
ES =0030 0000000000000000 ffffffff 00cf9300 DPL=0 DS [-WA]
CS =0038 0000000000000000 ffffffff 00af9a00 DPL=0 CS64 [-R-]
SS =0030 0000000000000000 ffffffff 00cf9300 DPL=0 DS [-WA]
DS =0030 0000000000000000 ffffffff 00cf9300 DPL=0 DS [-WA]
FS =0030 0000000000000000 ffffffff 00cf9300 DPL=0 DS [-WA]
GS =0030 0000000000000000 ffffffff 00cf9300 DPL=0 DS [-WA]
LDT=0000 0000000000000000 0000ffff 00008200 DPL=0 LDT
TR =0000 0000000000000000 0000ffff 00008b00 DPL=0 TSS64-busy
GDT= 00000000079eea98 00000047
IDT= 000000000758f018 00000fff
CR0=80010033 CR2=0000000000000000 CR3=0000000007c01000 CR4=00000668
DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000
DR6=00000000ffff0ff0 DR7=0000000000000400
CCS=0000000000000044 CCD=0000000000000000 CCO=EFLAGS
EFER=0000000000000d00

NOTE[5]: Just to better help the investigation of the bug, I'd like to remark that the issue is NOT caused by an endless loop of triple-faults. I tried with -d cpu_reset and there is NO such loop. No triple fault whatsoever.

NOTE[6]: The OVMF version used for the test has been downloaded from:
https://www.kraxel.org/repos/jenkins/edk2/edk2.git-ovmf-x64-0-20200515.1398.g6ff7c838d0.noarch.rpm

but the issue is the same with older OVMF versions as well.

Please take a look at it, as the bug is NOT a corner case. QEMU 4.2.0 cannot boot with an UEFI firmware (OVMF) while virtualizing a x86_64 machine AT ALL.

Thank you very much,
Vladislav K. Valtchev