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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BUG: KMSAN: uninit-value in vmcs_clear arch/x86/kvm/vmx.c:2119 [inline]
BUG: KMSAN: uninit-value in loaded_vmcs_init arch/x86/kvm/vmx.c:2126 [inline]
BUG: KMSAN: uninit-value in alloc_loaded_vmcs arch/x86/kvm/vmx.c:4769 [inline]
BUG: KMSAN: uninit-value in vmx_create_vcpu+0x10df/0x7920 arch/x86/kvm/vmx.c:10988
CPU: 0 PID: 7956 Comm: syz-executor5 Not tainted 4.19.0-rc4+ #63
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+0x306/0x460 lib/dump_stack.c:113
 kmsan_report+0x1a3/0x2d0 mm/kmsan/kmsan.c:917
 __msan_warning+0x7c/0xe0 mm/kmsan/kmsan_instr.c:500
 vmcs_clear arch/x86/kvm/vmx.c:2119 [inline]
 loaded_vmcs_init arch/x86/kvm/vmx.c:2126 [inline]
 alloc_loaded_vmcs arch/x86/kvm/vmx.c:4769 [inline]
 vmx_create_vcpu+0x10df/0x7920 arch/x86/kvm/vmx.c:10988
 kvm_arch_vcpu_create+0x25d/0x2f0 arch/x86/kvm/x86.c:8452
 kvm_vm_ioctl_create_vcpu arch/x86/kvm/../../../virt/kvm/kvm_main.c:2476 [inline]
 kvm_vm_ioctl+0x13fd/0x33d0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2977
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0xcf3/0x2810 fs/ioctl.c:687
 ksys_ioctl fs/ioctl.c:702 [inline]
 __do_sys_ioctl fs/ioctl.c:709 [inline]
 __se_sys_ioctl+0x1da/0x270 fs/ioctl.c:707
 __x64_sys_ioctl+0x4a/0x70 fs/ioctl.c:707
 do_syscall_64+0xbe/0x100 arch/x86/entry/common.c:291
 entry_SYSCALL_64_after_hwframe+0x63/0xe7
RIP: 0033:0x457579
Code: 1d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f59cdb26c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457579
RDX: 0000000000000000 RSI: 000000000000ae41 RDI: 0000000000000004
RBP: 000000000072bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f59cdb276d4
R13: 00000000004bfc18 R14: 00000000004cfca0 R15: 00000000ffffffff

Local variable description: ----c.i.i.i.i.i.i@vmx_create_vcpu
Variable was created at:
 vmx_create_vcpu+0xd5/0x7920 arch/x86/kvm/vmx.c:10952
 kvm_arch_vcpu_create+0x25d/0x2f0 arch/x86/kvm/x86.c:8452
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