L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/l1tf.html for details.
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kernel BUG at arch/x86/kvm/x86.c:353!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 5794 Comm: syz-executor135 Not tainted 4.19.0-rc7+ #54
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:kvm_spurious_fault+0x9/0x10 arch/x86/kvm/x86.c:353
Code: 45 10 50 e8 e9 44 7c 00 58 5a 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 e8 97 03 73 00 <0f> 0b 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 55 41 89 fd 41 54
RSP: 0018:ffff8801d373edc0 EFLAGS: 00010093
RAX: ffff8801d3d121c0 RBX: 1ffff1003a6e7dbc RCX: ffffffff81385bcc
RDX: 0000000000000000 RSI: ffffffff810bd1f9 RDI: ffff8801d373ee00
RBP: ffff8801d373edc0 R08: ffff8801d3d121c0 R09: fffff520003cea47
R10: fffff520003cea47 R11: ffffc90001e7523b R12: ffff8801d373ee40
R13: dffffc0000000000 R14: ffff8801bba7f000 R15: ffff8801d373ee00
FS:  00000000020e8880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8801d373ee00 CR3: 00000001bfd37000 CR4: 00000000001426f0
Call Trace:
 kvm_fastop_exception+0x50b/0x5455
 loaded_vmcs_init arch/x86/kvm/vmx.c:2129 [inline]
 __loaded_vmcs_clear+0x2d6/0x690 arch/x86/kvm/vmx.c:2212
 generic_exec_single+0x373/0x5f0 kernel/smp.c:153
 smp_call_function_single+0x1b2/0x660 kernel/smp.c:299
 loaded_vmcs_clear arch/x86/kvm/vmx.c:2221 [inline]
 free_loaded_vmcs+0x13c/0x1b0 arch/x86/kvm/vmx.c:4746
 vmx_free_vcpu+0x204/0x300 arch/x86/kvm/vmx.c:10982
 kvm_arch_vcpu_free arch/x86/kvm/x86.c:8457 [inline]
 kvm_free_vcpus arch/x86/kvm/x86.c:8909 [inline]
 kvm_arch_destroy_vm+0x365/0x7c0 arch/x86/kvm/x86.c:9006
 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:752 [inline]
 kvm_put_kvm+0x6c8/0xff0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:773
 kvm_vm_release+0x42/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:784
 __fput+0x385/0xa30 fs/file_table.c:278
 ____fput+0x15/0x20 fs/file_table.c:309
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x1ad7/0x2610 kernel/exit.c:867
 do_group_exit+0x177/0x440 kernel/exit.c:970
 __do_sys_exit_group kernel/exit.c:981 [inline]
 __se_sys_exit_group kernel/exit.c:979 [inline]
 __x64_sys_exit_group+0x3e/0x50 kernel/exit.c:979
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43f328
Code: 50 02 48 89 54 24 18 0f b6 50 02 83 e2 df 80 fa 50 75 8e 48 83 c0 03 41 bd 09 00 00 00 48 89 44 24 18 8d 41 fd 85 c0 89 44 24 <14> 0f 84 70 ff ff ff 48 8b 44 24 18 0f b6 10 48 8d 70 01 48 89 74
RSP: 002b:00007ffd60a95018 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000043f328
RDX: 0000000000000000 RSI: 000000000000003c RDI: 0000000000000000
RBP: 00000000004bf3e8 R08: 00000000000000e7 R09: ffffffffffffffd0
R10: 6c616b7a79732f2e R11: 0000000000000246 R12: 0000000000000001
R13: 00000000006d1180 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 31451759bc4fae62 ]---
RIP: 0010:kvm_spurious_fault+0x9/0x10 arch/x86/kvm/x86.c:353
Code: 45 10 50 e8 e9 44 7c 00 58 5a 48 8d 65 d8 5b 41 5c 41 5d 41 5e 41 5f 5d c3 0f 1f 84 00 00 00 00 00 55 48 89 e5 e8 97 03 73 00 <0f> 0b 0f 1f 44 00 00 55 48 89 e5 41 57 41 56 41 55 41 89 fd 41 54
RSP: 0018:ffff8801d373edc0 EFLAGS: 00010093
RAX: ffff8801d3d121c0 RBX: 1ffff1003a6e7dbc RCX: ffffffff81385bcc
RDX: 0000000000000000 RSI: ffffffff810bd1f9 RDI: ffff8801d373ee00
RBP: ffff8801d373edc0 R08: ffff8801d3d121c0 R09: fffff520003cea47
R10: fffff520003cea47 R11: ffffc90001e7523b R12: ffff8801d373ee40
R13: dffffc0000000000 R14: ffff8801bba7f000 R15: ffff8801d373ee00
FS:  00000000020e8880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffff8801d373ee00 CR3: 00000001bfd37000 CR4: 00000000001426f0