I am having trouble retrieving xen coverage. I compiled and installed xen stable 4.16 on Debian 11, enabling support for coverage (using gcov).
 
To reproduce my scenario: 
-  make -C xen menuconfig
-  disable flag /CommonFeatures/LivePatchingSupport.
-  enable enable DebuggingOptions/CodeCoverageSupport.
 
Once xen is installed, if I run the xencov utility from dom0 userspace, or invoke the SYSCTL_coverage_op hypervcall I get a hypervisor crash resulting from a page fault in the function xc_sysctl().
 
Carmine.