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.
BUG: unable to handle page fault for address: ffffed12f97c241f
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 21fff0067 P4D 21fff0067 PUD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9302 Comm: syz-executor225 Not tainted 5.2.0-rc6-next-20190628 #25
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:coalesced_mmio_write+0x28a/0x4d0 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:83
Code: 38 d0 7c 08 84 d2 0f 85 55 02 00 00 41 8b 47 04 48 8d 14 40 49 8d 7c d7 08 48 ba 00 00 00 00 00 fc ff df 48 89 fe 48 c1 ee 03 <80> 3c 16 00 0f 85 1b 02 00 00 48 8d 14 40 48 be 00 00 00 00 00 fc
RSP: 0018:ffff888095967168 EFLAGS: 00010a02
RAX: 00000000f7d5760a RBX: 0000000000000000 RCX: ffffffff81083dfa
RDX: dffffc0000000000 RSI: 1ffff112f97c241f RDI: ffff8897cbe120f8
RBP: ffff8880959671b8 R08: ffff888095d52080 R09: 0000000000000000
R10: ffffed1012b2ce1a R11: 0000000000000003 R12: 0000000000000001
R13: ffff8880a1c3ce10 R14: 0000000000000001 R15: ffff88808fde1000
FS:  00005555570fb940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed12f97c241f CR3: 000000009307b000 CR4: 00000000001526f0
Call Trace:
 kvm_iodevice_write include/kvm/iodev.h:54 [inline]
 __kvm_io_bus_write+0x29b/0x380 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3698
 kvm_io_bus_write+0x15c/0x290 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3723
 vcpu_mmio_write arch/x86/kvm/x86.c:5055 [inline]
 write_mmio+0x18e/0x510 arch/x86/kvm/x86.c:5417
 emulator_read_write_onepage+0x429/0xd80 arch/x86/kvm/x86.c:5486
 emulator_read_write+0x1b7/0x5a0 arch/x86/kvm/x86.c:5535
 emulator_write_emulated+0x3c/0x50 arch/x86/kvm/x86.c:5572
 segmented_write+0xf0/0x150 arch/x86/kvm/emulate.c:1444
 writeback arch/x86/kvm/emulate.c:1806 [inline]
 writeback+0x3f4/0x6a0 arch/x86/kvm/emulate.c:1792
 x86_emulate_insn+0x1911/0x4620 arch/x86/kvm/emulate.c:5693
 x86_emulate_instruction+0x70b/0x1cf0 arch/x86/kvm/x86.c:6535
 kvm_mmu_page_fault+0x370/0x1890 arch/x86/kvm/mmu.c:5436
 handle_ept_violation+0x1e1/0x530 arch/x86/kvm/vmx/vmx.c:5120
 vmx_handle_exit+0x299/0x15a0 arch/x86/kvm/vmx/vmx.c:5885
 vcpu_enter_guest+0xf74/0x5d90 arch/x86/kvm/x86.c:8032
 vcpu_run arch/x86/kvm/x86.c:8096 [inline]
 kvm_arch_vcpu_ioctl_run+0x463/0x1790 arch/x86/kvm/x86.c:8304
 kvm_vcpu_ioctl+0x4dc/0xfc0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2752
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0xdb6/0x13e0 fs/ioctl.c:696
 ksys_ioctl+0xab/0xd0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718
 do_syscall_64+0xfd/0x6a0 arch/x86/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4444e9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 1b 0c fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffdc5f54e48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffdc5f54e50 RCX: 00000000004444e9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000402240 R09: 0000000000402240
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000405590
R13: 0000000000405620 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
CR2: ffffed12f97c241f
---[ end trace 1377fbcddaf2f288 ]---
RIP: 0010:coalesced_mmio_write+0x28a/0x4d0 arch/x86/kvm/../../../virt/kvm/coalesced_mmio.c:83
Code: 38 d0 7c 08 84 d2 0f 85 55 02 00 00 41 8b 47 04 48 8d 14 40 49 8d 7c d7 08 48 ba 00 00 00 00 00 fc ff df 48 89 fe 48 c1 ee 03 <80> 3c 16 00 0f 85 1b 02 00 00 48 8d 14 40 48 be 00 00 00 00 00 fc
RSP: 0018:ffff888095967168 EFLAGS: 00010a02
RAX: 00000000f7d5760a RBX: 0000000000000000 RCX: ffffffff81083dfa
RDX: dffffc0000000000 RSI: 1ffff112f97c241f RDI: ffff8897cbe120f8
RBP: ffff8880959671b8 R08: ffff888095d52080 R09: 0000000000000000
R10: ffffed1012b2ce1a R11: 0000000000000003 R12: 0000000000000001
R13: ffff8880a1c3ce10 R14: 0000000000000001 R15: ffff88808fde1000
FS:  00005555570fb940(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffed12f97c241f CR3: 000000009307b000 CR4: 00000000001526f0