Add a warning if HVM is not enabled

[anthonycorreia]

Is your feature request related to a problem? Please describe.
I wanted to migrate a VM to a new, freshly installed host. I ended up each time with an error: "INTERNAL_ERROR". After several hours of debugging, I found out my destination host doesn't have the feature HVM enable !

Describe the solution you'd like
I would like to have a warning on XO to tell me that HVM feature is not enabled on my host. I think that Home -> Host, in the warning button next to the host name is a good place to have this warning. It can save some debugging time to other

The HVM capabilities can be found with xe host-param-list uuid=<Host_UUID>

If HVM is active :

capabilities (SRO): xen-3.0-x86_64;capabilities (SRO): xen-3.0-x86_64; hvm-3.0-x86_32; hvm-3.0-x86_32p; hvm-3.0-x86_64;

If HVM is inactive :

capabilities (SRO): xen-3.0-x86_64;

Describe alternatives you've considered
Maybe we can imagine a warning popup when the host is added to XO, but I think it would be more difficult to implement

Additional context
Thanks for the help and your work 🚀

[julien-f]

Hardware assisted virtualization is not enabled on this host