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.
faulting far call emulation tainted memory
------------[ cut here ]------------
WARNING: CPU: 1 PID: 4168 at arch/x86/kvm/x86.c:10394 kvm_arch_vcpu_ioctl_run+0x44c/0x1f40 arch/x86/kvm/x86.c:10394
Modules linked in:
CPU: 1 PID: 4168 Comm: syz-executor366 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:kvm_arch_vcpu_ioctl_run+0x44c/0x1f40 arch/x86/kvm/x86.c:10394
Code: fc ff df 42 80 3c 20 00 74 08 4c 89 ef e8 cc 5e ae 00 4d 8b 6d 00 31 ff 4c 89 ee e8 ce ec 68 00 4d 85 ed 74 09 e8 e4 e8 68 00 <0f> 0b eb 3f 4c 8d ab 20 01 00 00 4c 89 e8 48 c1 e8 03 42 0f b6 04
RSP: 0018:ffffc90002e6fc30 EFLAGS: 00010293
RAX: ffffffff810eee50 RBX: ffff88807a654000 RCX: ffff888074043b80
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: dffffc0000000000 R09: fffffbfff1ad1556
R10: fffffbfff1ad1556 R11: 1ffffffff1ad1555 R12: dffffc0000000000
R13: ffff88807a654120 R14: ffff88807a6540f0 R15: ffff88801d527000
FS:  000055555ff08380(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000559d6e436000 CR3: 0000000017d98000 CR4: 00000000003526e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kvm_vcpu_ioctl+0x887/0xb80 virt/kvm/kvm_main.c:3894
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f12aa4c71f9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc7ac1e1c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffc7ac1e398 RCX: 00007f12aa4c71f9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 00007f12aa53a610 R08: 00007ffc7ac1e398 R09: 00007ffc7ac1e398
R10: 00007ffc7ac1e398 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffc7ac1e388 R14: 0000000000000001 R15: 0000000000000001
 </TASK>