L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.
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WARNING: CPU: 0 PID: 8104 at arch/x86/kvm/vmx.c:7239 handle_desc.cold+0x11/0x18 arch/x86/kvm/vmx.c:7239
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 8104 Comm: syz-executor672 Not tainted 4.19.163-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1fc/0x2fe lib/dump_stack.c:118
 panic+0x26a/0x50e kernel/panic.c:186
 __warn.cold+0x20/0x61 kernel/panic.c:541
 report_bug+0x262/0x2b0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [inline]
 do_error_trap+0x1d7/0x310 arch/x86/kernel/traps.c:296
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:handle_desc.cold+0x11/0x18 arch/x86/kvm/vmx.c:7239
Code: 00 48 c7 c7 40 ca 63 88 c6 05 47 f5 09 0a 01 e8 06 28 33 00 e9 04 30 fc ff e8 6d 2e 48 00 48 c7 c7 e0 c5 63 88 e8 f0 27 33 00 <0f> 0b e9 a2 3b fc ff e8 55 2e 48 00 89 de 48 c7 c7 e0 cc 63 88 c6
RSP: 0018:ffff88808eb57968 EFLAGS: 00010286
RAX: 0000000000000024 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff814fdbb1 RDI: ffffed1011d6af1f
RBP: ffff8880b1578040 R08: 0000000000000024 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000000000000 R12: 000000000000002e
R13: dffffc0000000000 R14: 0000000000000000 R15: ffff8880b1578040
 vmx_handle_exit+0x26c/0xf90 arch/x86/kvm/vmx.c:10168
 vcpu_enter_guest arch/x86/kvm/x86.c:7831 [inline]
 vcpu_run arch/x86/kvm/x86.c:7894 [inline]
 kvm_arch_vcpu_ioctl_run+0x2956/0x6e30 arch/x86/kvm/x86.c:8094
 kvm_vcpu_ioctl+0x493/0xe10 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2823
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcdb/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x442959
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 9b 0b fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff36712fd8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000442959
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00000000006cf018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000403980
R13: 0000000000403a10 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..