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: 1 PID: 6830 at arch/x86/kvm/vmx/vmx.c:4809 handle_exception_nmi+0x1051/0x12a0 arch/x86/kvm/vmx/vmx.c:4809
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 6830 Comm: syz-executor736 Not tainted 5.9.0-rc6-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+0x1d6/0x29e lib/dump_stack.c:118
 panic+0x2c0/0x800 kernel/panic.c:231
 __warn+0x227/0x250 kernel/panic.c:600
 report_bug+0x1b1/0x2e0 lib/bug.c:198
 handle_bug+0x42/0x80 arch/x86/kernel/traps.c:234
 exc_invalid_op+0x16/0x40 arch/x86/kernel/traps.c:254
 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536
RIP: 0010:handle_exception_nmi+0x1051/0x12a0 arch/x86/kvm/vmx/vmx.c:4809
Code: e8 98 00 e9 17 f1 ff ff 89 d9 80 e1 07 80 c1 03 38 c1 0f 8c da f0 ff ff 48 89 df e8 99 e8 98 00 e9 cd f0 ff ff e8 cf 18 59 00 <0f> 0b e9 e0 f6 ff ff 89 d1 80 e1 07 80 c1 03 38 c1 0f 8c f4 f1 ff
RSP: 0018:ffffc900011df9b0 EFLAGS: 00010293
RAX: ffffffff811be461 RBX: ffffffffef6686b0 RCX: ffff88808a0ec140
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001
RBP: 0000000000000000 R08: ffffffff811bdb3a R09: ffffed1014e12871
R10: ffffed1014e12871 R11: 0000000000000000 R12: ffff8880a7094380
R13: 1ffff11014e12826 R14: ffff8880a7094040 R15: 0000000000000002
 vcpu_enter_guest+0x6725/0x8a50 arch/x86/kvm/x86.c:8655
 vcpu_run+0x332/0xc00 arch/x86/kvm/x86.c:8720
 kvm_arch_vcpu_ioctl_run+0x451/0x8f0 arch/x86/kvm/x86.c:8937
 kvm_vcpu_ioctl+0x64f/0xa50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3230
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xfb/0x170 fs/ioctl.c:739
 do_syscall_64+0x31/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x443479
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:00007ffdb9f41628 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 0000000000443479
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00000000006cd018 R08: 0000000000000000 R09: 00000000004002c8
R10: 0000000000000012 R11: 0000000000000246 R12: 00000000004044a0
R13: 0000000000404530 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..