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.
kvm [8418]: vcpu0, guest rIP: 0x145 Hyper-V unhandled rdmsr: 0x4000004c
BUG: kernel NULL pointer dereference, address: 0000000000000086
#PF: supervisor instruction fetch in kernel mode
#PF: error_code(0x0010) - not-present page
PGD 50e3c067 P4D 50e3c067 PUD 50e3b067 PMD 0 
Oops: 0010 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 8419 Comm: syz-executor.3 Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:0x86
Code: Bad RIP value.
RSP: 0018:ffffc90001eef998 EFLAGS: 00010086
RAX: ffffc90001eef9c8 RBX: fffffe0000000000 RCX: 0000000000040000
RDX: ffffc9000fbbd000 RSI: 000000000000d29c RDI: 000000000000d29d
RBP: 0000000000000ec0 R08: ffffffff8398c3c3 R09: ffffffff811c7eca
R10: ffff8880546345c0 R11: 0000000000000002 R12: dffffc0000000000
R13: fffffe0000000ec8 R14: ffffffff880016f0 R15: fffffe0000000ecb
FS:  00007f9891598700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000005c CR3: 00000000a2ad1000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 handle_external_interrupt_irqoff+0x154/0x280 arch/x86/kvm/vmx/vmx.c:6274
 kvm_before_interrupt arch/x86/kvm/x86.h:343 [inline]
 handle_external_interrupt_irqoff+0x132/0x280 arch/x86/kvm/vmx/vmx.c:6272
 __irqentry_text_start+0x8/0x8
 vcpu_enter_guest+0x6c77/0x9290 arch/x86/kvm/x86.c:8405
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x220 mm/slab.c:3757
 test_bit include/asm-generic/bitops/instrumented-non-atomic.h:110 [inline]
 hlock_class kernel/locking/lockdep.c:163 [inline]
 mark_lock+0x107/0x1650 kernel/locking/lockdep.c:3642
 mark_held_locks kernel/locking/lockdep.c:3359 [inline]
 __trace_hardirqs_on_caller kernel/locking/lockdep.c:3388 [inline]
 lockdep_hardirqs_on+0x4f4/0x840 kernel/locking/lockdep.c:3433
 trace_hardirqs_on_thunk+0x1a/0x1c arch/x86/entry/thunk_64.S:41
 mark_held_locks kernel/locking/lockdep.c:3359 [inline]
 __trace_hardirqs_on_caller kernel/locking/lockdep.c:3388 [inline]
 lockdep_hardirqs_on+0x4f4/0x840 kernel/locking/lockdep.c:3433
 trace_hardirqs_on_thunk+0x1a/0x1c arch/x86/entry/thunk_64.S:41
 trace_hardirqs_on_thunk+0x1a/0x1c arch/x86/entry/thunk_64.S:41
 check_preemption_disabled+0xa2/0x240 lib/smp_processor_id.c:19
 retint_kernel+0x2b/0x2b
 vcpu_block arch/x86/kvm/x86.c:8463 [inline]
 vcpu_run+0x381/0xd50 arch/x86/kvm/x86.c:8515
 clear_bit include/asm-generic/bitops/instrumented-atomic.h:41 [inline]
 kvm_clear_request include/linux/kvm_host.h:1237 [inline]
 vcpu_run+0x5ce/0xd50 arch/x86/kvm/x86.c:8521
 kvm_check_async_pf_completion+0x34e/0x360 arch/x86/kvm/../../../virt/kvm/async_pf.c:137
 vcpu_run+0x3a3/0xd50 arch/x86/kvm/x86.c:8513
 kvm_arch_vcpu_ioctl_run+0x419/0x880 arch/x86/kvm/x86.c:8735
 kvm_vcpu_ioctl+0x67c/0xa80 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2932
 kvm_vm_release+0x50/0x50 arch/x86/kvm/../../../virt/kvm/kvm_main.c:858
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl fs/ioctl.c:763 [inline]
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
 do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
Modules linked in:
CR2: 0000000000000086
---[ end trace 25d88e45dd52af00 ]---
RIP: 0010:0x86
Code: Bad RIP value.
RSP: 0018:ffffc90001eef998 EFLAGS: 00010086
RAX: ffffc90001eef9c8 RBX: fffffe0000000000 RCX: 0000000000040000
RDX: ffffc9000fbbd000 RSI: 000000000000d29c RDI: 000000000000d29d
RBP: 0000000000000ec0 R08: ffffffff8398c3c3 R09: ffffffff811c7eca
R10: ffff8880546345c0 R11: 0000000000000002 R12: dffffc0000000000
R13: fffffe0000000ec8 R14: ffffffff880016f0 R15: fffffe0000000ecb
FS:  00007f9891598700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000000005c CR3: 00000000a2ad1000 CR4: 00000000001426f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400