@andSmv thanks for the reply
The server is a home test, power consumption is more important than stability, so I'll try to recompile xen.I guess it will be enough to recompile only version 4.13.4 ?
PS.: I just looked at the source code and I don't see that there is a switch to turn it off. I will modify mwait-idle.c to see if it works 
PS2: Done :
[09:50 home-xcp ~]# xenpm get-cpuidle-states 0
Max possible C-state: C9
cpu id : 0
total C-states : 5
idle time(ms) : 134037
C0 : transition [ 5351]
residency [ 6507 ms]
C1 : transition [ 13]
residency [ 15 ms]
C2 : transition [ 71]
residency [ 120 ms]
C3 : transition [ 701]
residency [ 6956 ms]
C4 : transition [ 4566]
residency [ 120437 ms]
pc3 : [ 13371 ms]
pc6 : [ 23594 ms]
cc3 : [ 14446 ms]
cc6 : [ 63719 ms]
The intel.c had to be modified to be correct. Let's see how stable it will be.