Comment 1 for bug 1935880

I attached gdb to the VM[*] and retrieved the following backtrace from the guest kernel:

(gdb) bt full
#0 pci_conf1_read (seg=<optimized out>, bus=<optimized out>, devfn=<optimized out>, reg=16, len=4, value=0xffffc9000001fa0c) at /home/dannf/linux-kvm-5.4.0/arch/x86/pci/direct.c:35
        flags = 582
        __dummy = <optimized out>
        __dummy2 = <optimized out>
        __dummy = <optimized out>
        __dummy2 = <optimized out>
#1 0xffffffff815a1964 in raw_pci_read (domain=<optimized out>, bus=<optimized out>, devfn=<optimized out>, reg=<optimized out>, len=<optimized out>, val=<optimized out>) at /home/dannf/linux-kvm-5.4.0/arch/x86/pci/common.c:46
No locals.
#2 0xffffffff815a19a7 in pci_read (bus=<optimized out>, devfn=<optimized out>, where=<optimized out>, size=<optimized out>, value=<optimized out>) at /home/dannf/linux-kvm-5.4.0/arch/x86/include/asm/pci.h:45
No locals.
#3 0xffffffff8144f4c5 in pci_bus_read_config_dword (bus=<optimized out>, devfn=<optimized out>, pos=<optimized out>, value=0xffffc9000001fa58) at /home/dannf/linux-kvm-5.4.0/drivers/pci/access.c:65
        res = -2147480816
        flags = <optimized out>
        data = 0
#4 0xffffffff8144f7f2 in pci_read_config_dword (dev=<optimized out>, where=<optimized out>, val=<optimized out>) at /home/dannf/linux-kvm-5.4.0/drivers/pci/access.c:550
No locals.
#5 0xffffffff8145142a in __pci_read_base (dev=0xffff888000d8d000, type=pci_bar_unknown, res=0xffff888000d8d278, pos=16) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:196
        l = 0
        sz = 0
        mask = <optimized out>
        l64 = <optimized out>
        sz64 = <optimized out>
        mask64 = <optimized out>
        orig_cmd = 7
        region = {start = 18446683600570153584, end = 18446744071584749924}
        inverted_region = {start = 18446683600570153600, end = 18446744071584749991}
#6 0xffffffff81451757 in pci_read_bases (dev=0xffff888000d8d000, howmany=2, rom=56) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:334
        res = <optimized out>
        pos = 0
        reg = <optimized out>
        res = <optimized out>
#7 0xffffffff81451dd4 in pci_setup_device (dev=0xffff888000d8d000) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:1854
        class = 1540
        cmd = 34750
        hdr_type = <optimized out>
        pos = <optimized out>
        region = {start = 18446683600670950407, end = 18446744071583369946}
        res = <optimized out>
#8 0xffffffff81452950 in pci_scan_device (devfn=<optimized out>, bus=<optimized out>) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:2301
        dev = 0xffff888000d8d000
        l = 793398
        dev = <optimized out>
        l = <optimized out>
#9 pci_scan_single_device (devfn=<optimized out>, bus=<optimized out>) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:2474
        dev = <optimized out>
        dev = <optimized out>
#10 pci_scan_single_device (bus=0xffff888000c76c00, devfn=11) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:2464
        dev = 0x0 <fixed_percpu_data>
#11 0xffffffff81452a02 in pci_scan_slot (bus=0xffff888000c76c00, devfn=8) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:2560
        fn = 3
        nr = 3
        dev = <optimized out>
#12 0xffffffff81453a71 in pci_scan_child_bus_extend (bus=0xffff888000c76c00, available_buses=<optimized out>) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:2770
        used_buses = <optimized out>
        normal_bridges = <optimized out>
        hotplug_bridges = <optimized out>
        start = <optimized out>
        devfn = 16
        fn = <optimized out>
        cmax = <optimized out>
        max = <optimized out>
        dev = <optimized out>
        nr_devs = <optimized out>
        __mptr = <optimized out>
#13 0xffffffff81453c6b in pci_scan_child_bus (bus=<optimized out>) at /home/dannf/linux-kvm-5.4.0/drivers/pci/probe.c:2900
No locals.
#14 0xffffffff814896df in acpi_pci_root_create (root=<optimized out>, ops=<optimized out>, info=0xffff8880001e5600, sysdata=<optimized out>) at /home/dannf/linux-kvm-5.4.0/drivers/acpi/pci_root.c:931
        ret = <optimized out>
        busnum = <optimized out>
        device = <optimized out>
        node = <optimized out>
        bus = 0xffff888000c76c00
        host_bridge = <optimized out>
        obj = <optimized out>
#15 0xffffffff815a0c00 in pci_acpi_scan_root (root=0xffff888000091b00) at /home/dannf/linux-kvm-5.4.0/arch/x86/pci/acpi.c:368
        info = <optimized out>
        domain = 0
        busnum = <optimized out>
        node = <optimized out>
        bus = 0xffff8880001e5600
#16 0xffffffff814893be in acpi_pci_root_add (device=0xffff888000c78000, not_used=<optimized out>) at /home/dannf/linux-kvm-5.4.0/drivers/acpi/pci_root.c:603
        segment = 0
        bus = 18446744071594171520
        status = <optimized out>
        result = <optimized out>
        root = <optimized out>
        handle = 0xffff888000d121e0
        no_aspm = 0
        hotadd = <optimized out>
        is_pcie = <optimized out>
#17 0xffffffff81482cd9 in acpi_scan_attach_handler (device=<optimized out>) at /home/dannf/linux-kvm-5.4.0/drivers/acpi/scan.c:1985
        devid = 0xffffffff81ca77c0 <root_device_ids>
        handler = <optimized out>
        hwid = 0xffff8880001f21c0
        ret = <optimized out>
        hwid = <optimized out>
        ret = <optimized out>
        __mptr = <optimized out>
        devid = <optimized out>
        handler = <optimized out>
        __mptr = <optimized out>
#18 acpi_bus_attach (device=0xffff888000c78000) at /home/dannf/linux-kvm-5.4.0/drivers/acpi/scan.c:2029
        child = <optimized out>
        ejd = 0xffff888000c79890
        ret = <optimized out>
#19 0xffffffff81482c48 in acpi_bus_attach (device=0xffff888000c79800) at /home/dannf/linux-kvm-5.4.0/drivers/acpi/scan.c:2050
        child = 0xffff888000c78000
        ejd = 0xffff888000c7a090
        ret = <optimized out>
#20 0xffffffff81482c48 in acpi_bus_attach (device=0xffff888000c7a000) at /home/dannf/linux-kvm-5.4.0/drivers/acpi/scan.c:2050
        child = 0xffff888000c79800
        ejd = 0x0 <fixed_percpu_data>
        ret = <optimized out>
#21 0xffffffff81484bc3 in acpi_bus_scan (handle=0xffffffffffffffff) at /home/dannf/linux-kvm-5.4.0/drivers/acpi/scan.c:2102
        device = 0xffff888000c7a000
#22 0xffffffff81f6dbfb in acpi_scan_init () at /home/dannf/linux-kvm-5.4.0/drivers/acpi/scan.c:2262
        result = 0
        status = <optimized out>
        stao_ptr = 0x0 <fixed_percpu_data>
#23 0xffffffff81f6d92a in acpi_init () at /home/dannf/linux-kvm-5.4.0/drivers/acpi/bus.c:1249
        result = <optimized out>
        __func__ = "acpi_init"
#24 0xffffffff81000bc1 in do_one_initcall (fn=0xffffffff81f6d68c <acpi_init>) at /home/dannf/linux-kvm-5.4.0/init/main.c:941
        count = <optimized out>
        msgbuf = "\000:ہ\377\377\377\377\004\000\004\000\277\000\000\000\250Xہ\377\377\377\377\201\307\006z\200\210\377\377\207\307\006z\200\210\377\377\000P(joZ\236\301\004\000\000\000\000\000\000\000\277\000\000\000\000\000\000"
        ret = -2113897520
#25 0xffffffff81f2f208 in do_initcall_level (level=<optimized out>) at /home/dannf/linux-kvm-5.4.0/include/linux/compiler.h:377
        fn = 0xffffffff82007bd0
        fn = <optimized out>
#26 do_initcalls () at /home/dannf/linux-kvm-5.4.0/init/main.c:1017
        level = <optimized out>
        level = <optimized out>
#27 do_basic_setup () at /home/dannf/linux-kvm-5.4.0/init/main.c:1034
No locals.
#28 kernel_init_freeable () at /home/dannf/linux-kvm-5.4.0/init/main.c:1195
No locals.
#29 0xffffffff8174d4c9 in kernel_init (unused=<optimized out>) at /home/dannf/linux-kvm-5.4.0/init/main.c:1112
        ret = <optimized out>
#30 0xffffffff81800215 in ret_from_fork () at /home/dannf/linux-kvm-5.4.0/arch/x86/entry/entry_64.S:352

[*] lxc uses images with the -kvm variant kernel, which does not include debug symbols (bug 1935855). So this is actually from a local rebuild w/ CONFIG_DEBUG_INFO=y. Also, since lxc launches guests w/ Secure Boot enabled, I loaded a custom cert into the UEFI DB and self-signed my build.