QEMU Segmentation fault - Xen / Ubuntu 18.04
Description of problem:
See notes below.
Steps to reproduce:
See notes below.
Additional information:
* The error is very rare.
* The VMs have been created with `xl create` (Xen utility).
* The error has been found with _coredump_ ([core.qemu-system-i38.0.abb1047980ee4143937dcce7b8da9e60.16892.1634806267000000.lz4](/uploads/a90e21a2e14c9ebba07585034de25b1a/core.qemu-system-i38.0.abb1047980ee4143937dcce7b8da9e60.16892.1634806267000000.lz4)):
```bash
$ sudo coredumpctl info 16892
           PID: 16892 (qemu-system-i38)
           UID: 0 (root)                               
           GID: 0 (root)                                                                                                                                                                                                                      
        Signal: 11 (SEGV)                
     Timestamp: Thu 2021-10-21 11:51:07 MSK (17min ago)           
  Command Line: /usr/bin/qemu-system-i386 -xen-domid 2679 -no-shutdown -chardev socket,id=libxl-cmd,path=/var/run/xen/qmp-libxl-2679,server,nowait -mon chardev=libxl-cmd,mode=control -chardev socket,id=libxenstat-cmd,path=/var/run/xen/qmp
    Executable: /usr/bin/qemu-system-i386
 Control Group: /system.slice/ptms.sandbox.sandbox-creator.service
          Unit: ptms.sandbox.sandbox-creator.service
         Slice: system.slice
       Boot ID: abb1047980ee4143937dcce7b8da9e60                                                                            
    Machine ID: bdce82649a9d4d9db192a692b330943f                      
      Hostname: ptms-7
       Storage: /var/lib/systemd/coredump/core.qemu-system-i38.0.abb1047980ee4143937dcce7b8da9e60.16892.1634806267000000.lz4
       Message: Process 16892 (qemu-system-i38) of user 0 dumped core.         
                                                                           
                Stack trace of thread 16892:                 
                #0  0x00007f1c6d33ca5f __memmove_avx_unaligned_erms (libc.so.6)
                #1  0x00005586abeae8bf iov_from_buf_full (qemu-system-i386)
                #2  0x00005586abe03d46 n/a (qemu-system-i386)
                #3  0x00005586abdd17ad n/a (qemu-system-i386)
                #4  0x00005586abeac93c n/a (qemu-system-i386)        
                #5  0x00007f1c6d2067b0 n/a (libc.so.6)                
                #6  0x00005586abeb89bd n/a (qemu-system-i386)
                #7  0x00005586abeaaf87 aio_bh_poll (qemu-system-i386)            
                #8  0x00005586abe9a45e aio_dispatch (qemu-system-i386)  
                #9  0x00005586abeaad9e n/a (qemu-system-i386)           
                #10 0x00007f1c6fd7f537 g_main_context_dispatch (libglib-2.0.so.0)
                #11 0x00005586abeb5caa main_loop_wait (qemu-system-i386)
                #12 0x00005586abca092d qemu_main_loop (qemu-system-i386)
                #13 0x00005586ab9f508e main (qemu-system-i386)
                #14 0x00007f1c6d1cfbf7 __libc_start_main (libc.so.6)
                #15 0x00005586ab9f97fa _start (qemu-system-i386)
                                                                         
                Stack trace of thread 16932:                 
                #0  0x00007f1c6d2c9639 syscall (libc.so.6)   
                #1  0x00005586abe9de1b qemu_event_wait (qemu-system-i386)
                #2  0x00005586abea5e28 n/a (qemu-system-i386)
                #3  0x00005586abe9d0b6 n/a (qemu-system-i386)
                #4  0x00007f1c6d5a66db start_thread (libpthread.so.0)
                #5  0x00007f1c6d2cf71f __clone (libc.so.6)          
                                                               
                Stack trace of thread 16957:                   
                #0  0x00007f1c6d5b0474 __libc_read (libpthread.so.0)
                #1  0x00007f1c71f67777 n/a (libxenstore.so.3.0)      
                #2  0x00007f1c71f6784d n/a (libxenstore.so.3.0)
                #3  0x00007f1c71f67b61 n/a (libxenstore.so.3.0)
                #4  0x00007f1c6d5a66db start_thread (libpthread.so.0)
                #5  0x00007f1c6d2cf71f __clone (libc.so.6)          

                Stack trace of thread 16958:                   
                #0  0x00007f1c6d5b0474 __libc_read (libpthread.so.0)
                #1  0x00007f1c71f67777 n/a (libxenstore.so.3.0)      
                #2  0x00007f1c71f6784d n/a (libxenstore.so.3.0)
                #3  0x00007f1c71f67b61 n/a (libxenstore.so.3.0)
                #4  0x00007f1c6d5a66db start_thread (libpthread.so.0)
                #5  0x00007f1c6d2cf71f __clone (libc.so.6)
```