qemu-system-aarch64: Error: r = HV_BAD_ARGUMENT (0xfae94003, at ../target/arm/hvf/hvf.c:2259)

Host environment

• Operating system: macOS 15.3.2 (24D81)
• OS/kernel version: Darwin macos 24.3.0 Darwin Kernel Version 24.3.0: Thu Jan 2 20:23:36 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T8112 arm64
• Architecture: arm64
• QEMU flavor: qemu-system-aarch64
• QEMU version: 0f15892a
• QEMU command line:

/Volumes/src/qemu-project/qemu/build/qemu-system-aarch64 \
  -nodefaults \
  -nographic \
  -machine "virt" \
  -accel "hvf" \
  -cpu "host" \
  -smp "2" \
  -m "2G" \
  -bios "/Volumes/src/qemu-project/qemu/build/pc-bios/edk2-aarch64-code.fd" \
  -gdb "tcp::1234" \
  -netdev "user,id=net0,hostfwd=tcp::2222-:22" \
  -device "virtio-net-pci,netdev=net0" \
  -drive "id=boot,file=debian-13-genericcloud-arm64-daily.qcow2,format=qcow2,if=virtio,discard=unmap,media=disk,read-only=no" \
  -kernel "arch/arm64/boot/Image" \
  -append "root=/dev/vda1 audit=0 nokaslr console=ttyAMA0" \
  -serial "mon:stdio"

Emulated/Virtualized environment

• Operating system: Linux
• OS/kernel version: Upstream latest
• Architecture: arm64

Description of problem

When I launch a Linux guest in QEMU with -accel hvf + -gdb "tcp::1234", and I try to debug the kernel with lldb, QEMU crashes with the following report:

qemu-system-aarch64: Error: r = HV_BAD_ARGUMENT (0xfae94003, at ../target/arm/hvf/hvf.c:2259)

Steps to reproduce

1. Run QEMU with -accel hvf + -gdb "tcp::1234" and a custom kernel (-kernel Image)
2. Try to attach using lldb vmlinux + (lldb) gdb-remote 1234

Additional information

Debugging QEMU I see the crash is due to the cpu->accel->fd file descriptor being 0:

warning: qemu-system-aarch64 was compiled with optimization - stepping may behave oddly; variables may not be available.
frame #4: 0x00000001003dd24c qemu-system-aarch64`hvf_arch_update_guest_debug [inlined] hvf_put_guest_debug_registers(cpu=0x0000000158118000) at hvf.c:2259:9 [opt]
   2256     for (i = 0; i < max_hw_bps; i++) {
   2257         r = hv_vcpu_set_sys_reg(cpu->accel->fd, dbgbcr_regs[i],
   2258                                 env->cp15.dbgbcr[i]);
-> 2259         assert_hvf_ok(r);
   2260         r = hv_vcpu_set_sys_reg(cpu->accel->fd, dbgbvr_regs[i],
   2261                                 env->cp15.dbgbvr[i]);
   2262         assert_hvf_ok(r);
(lldb) print cpu->accel->fd
(hvf_vcpuid) 0
(lldb) print dbgbcr_regs[i]
(const uint16_t) 32773
(lldb) print env->cp15.dbgbcr[i]
(uint64_t) 480