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. ============================= WARNING: suspicious RCU usage 5.15.185-syzkaller #0 Not tainted ----------------------------- include/linux/kvm_host.h:889 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by syz.0.16/5042: #0: ffff88807cd6c0c8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x1c8/0xb80 virt/kvm/kvm_main.c:3871 stack backtrace: CPU: 0 PID: 5042 Comm: syz.0.16 Not tainted 5.15.185-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106 __kvm_memslots include/linux/kvm_host.h:887 [inline] kvm_vcpu_memslots+0x1b6/0x200 include/linux/kvm_host.h:901 kvm_vcpu_gfn_to_memslot+0x2b/0x3c0 virt/kvm/kvm_main.c:2158 kvm_vcpu_unmap+0x5b/0x80 virt/kvm/kvm_main.c:2773 nested_vmx_vmexit+0x13f5/0x28d0 arch/x86/kvm/vmx/nested.c:4676 vmx_leave_nested+0x7e/0xc0 arch/x86/kvm/vmx/nested.c:6342 kvm_leave_nested arch/x86/kvm/x86.c:618 [inline] kvm_vcpu_ioctl_x86_set_vcpu_events+0x95b/0x1190 arch/x86/kvm/x86.c:4812 kvm_arch_vcpu_ioctl+0x1092/0x19d0 arch/x86/kvm/x86.c:5297 kvm_vcpu_ioctl+0x6b1/0xb80 virt/kvm/kvm_main.c:4050 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: 0033:0x7fb785fb7969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fb785227038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fb7861defa0 RCX: 00007fb785fb7969 RDX: 0000200000000080 RSI: 000000004040aea0 RDI: 0000000000000005 RBP: 00007fb786039ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fb7861defa0 R15: 00007ffed7cf1ef8