------------[ cut here ]------------
WARNING: arch/x86/kvm/../../../virt/kvm/pfncache.c:267 at __kvm_gpc_refresh+0x1b21/0x2490 virt/kvm/pfncache.c:267, CPU#1: syz.1.196/6796
Modules linked in:
CPU: 1 UID: 0 PID: 6796 Comm: syz.1.196 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__kvm_gpc_refresh+0x1b21/0x2490 virt/kvm/pfncache.c:267
Code: 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 67 09 00 00 48 8b 04 24 31 db 48 8b a8 10 01 00 00 e9 f2 ef ff ff e8 90 6e 85 00 90 <0f> 0b 90 e9 92 f7 ff ff e8 82 6e 85 00 48 85 db 0f 84 b4 04 00 00
RSP: 0018:ffffc90004237108 EFLAGS: 00010283
RAX: 000000000000070b RBX: ffffffffffffffff RCX: ffffc9000c402000
RDX: 0000000000080000 RSI: ffffffff81390300 RDI: 0000000000000000
RBP: ffffffffffffff01 R08: 0000000000000000 R09: 0000000000000001
R10: 0000000000000001 R11: 000000000000001e R12: ffff888000000000
R13: ffff888000000001 R14: ffff888000000000 R15: ffffc90004237320
FS:  0000000000000000(0000) GS:ffff8880977f6000(0063) knlGS:00000000f540db40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000f72f8eb8 CR3: 000000004977a000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 kvm_gpc_refresh+0xec/0x190 virt/kvm/pfncache.c:382
 kvm_xen_set_evtchn.part.0+0x19c/0x270 arch/x86/kvm/xen.c:1943
 kvm_xen_set_evtchn arch/x86/kvm/xen.c:2044 [inline]
 kvm_xen_hvm_evtchn_send+0x22f/0x290 arch/x86/kvm/xen.c:2034
 kvm_arch_vm_ioctl+0xfac/0x18b0 arch/x86/kvm/x86.c:7490
 kvm_vm_ioctl+0x1b03/0x4090 virt/kvm/kvm_main.c:5402
 kvm_vm_compat_ioctl+0x393/0x3f0 virt/kvm/kvm_main.c:5482
 __do_compat_sys_ioctl fs/ioctl.c:695 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:638 [inline]
 __ia32_compat_sys_ioctl+0x242/0x370 fs/ioctl.c:638
 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline]
 __do_fast_syscall_32+0xe8/0x680 arch/x86/entry/syscall_32.c:307
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/syscall_32.c:332
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf701d579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f540d55c EFLAGS: 00000296 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 000000000000000d RCX: 00000000400caed0
RDX: 0000000080000980 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
   0:	10 06                	adc    %al,(%rsi)
   2:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
   6:	10 07                	adc    %al,(%rdi)
   8:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
   c:	10 08                	adc    %cl,(%rax)
   e:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1e:	00 51 52             	add    %dl,0x52(%rcx)
  21:	55                   	push   %rbp
  22:	89 e5                	mov    %esp,%ebp
  24:	0f 34                	sysenter
  26:	cd 80                	int    $0x80
* 28:	5d                   	pop    %rbp <-- trapping instruction
  29:	5a                   	pop    %rdx
  2a:	59                   	pop    %rcx
  2b:	c3                   	ret
  2c:	90                   	nop
  2d:	90                   	nop
  2e:	90                   	nop
  2f:	90                   	nop
  30:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi
  37:	8d b4 26 00 00 00 00 	lea    0x0(%rsi,%riz,1),%esi