Bug 1832721

Summary: [Docs] Add Nested Virt as Tech Preview for generic use
Product: Red Hat Enterprise Virtualization Manager Reporter: Martin Tessun <mtessun>
Component: DocumentationAssignee: Rolfe Dlugy-Hegwer <rdlugyhe>
Status: CLOSED DUPLICATE QA Contact: rhev-docs <rhev-docs>
Severity: high Docs Contact:
Priority: high    
Version: 4.4.0CC: lsurette, mhicks, michal.skrivanek, srevivo
Target Milestone: ovirt-4.4.3Keywords: Documentation, NoDocsQEReview
Target Release: 4.4.3   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: No Doc Update
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2020-09-28 23:33:25 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: Virt RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1794485    
Bug Blocks:    

Description Martin Tessun 2020-05-07 07:52:57 UTC
Please add Nested Virtualization as TechPreview feature in RHV 4.4.

Reason:
In RHEL 8.2 we will get Nested Virt fully supported for Intel CPUs.
With AMD and Power still missing Full Support, we only want Nested Virt as Tech Preview.

Comment 1 Steve Goodman 2020-05-07 08:07:38 UTC
Martin, Michal,

This is what we had in the 4.3 Tech Preview features table[1]:

----------------------------------------------------------------------------------
VDSM hook for nested virtualization | Allows a virtual machine to serve as a host.
----------------------------------------------------------------------------------

Is this what you want us to say? 

Where do you want this to be added in the Admin Guide and what specifically do you want us to say? This is what I'd like to know as a user:

What are benefits?
What are the risks?
How do I use it? (enabling/disabling it in WebUI (which portal(s)) and REST API, anything I need to do when installing/attaching hosts, what is the VDSM hook...anything else I'm not thinking of)

Comment 2 Steve Goodman 2020-05-07 08:11:41 UTC
I just found this in the 4.3 Technical Notes:

BZ#1421746

In this release, a new VDSM hook that configures nested virtualization, has been introduced as a Technology Preview. Support for nested virtualization was introduced in Red Hat Enterprise Linux 7 and it enables a virtual machine to serve as a host.
VDSM hooks are a means to insert code, commands, or scripts into a point in the lifecycle of a virtual machine or the VDSM daemon.

Comment 3 Michal Skrivanek 2020-05-07 10:01:03 UTC
ok, there was another existing bug already, just added a comment there. https://bugzilla.redhat.com/show_bug.cgi?id=1759205#c1

we should make it a bit more prominent and not just in a technical note. I think some place around host setup makes sense, We have a Host dialog Kernel tab where we have such things like passthrough setup, this is similar.

no API. No further configuration besides the hook

Comment 4 Michal Skrivanek 2020-05-14 06:41:08 UTC
[adding a blocker flag as this comes up more and more often]

and another one we already had for more than a year - bug 1759342. 

We also have a kbase https://access.redhat.com/solutions/3543721 which should be updated afterwards to point to documentation instead of current misleading/incomplete information. Note that the suggestion there is also a valid way how to use nesting (enable on hypervisor by other means or by Host/Kernel dialog, and then use VMs with Host CPU Passthrough). It's a less general alternative approach, so probably worth mentioning

Comment 5 Martin Tessun 2020-05-22 08:35:45 UTC
(In reply to Michal Skrivanek from comment #3)
> ok, there was another existing bug already, just added a comment there.
> https://bugzilla.redhat.com/show_bug.cgi?id=1759205#c1
> 
> we should make it a bit more prominent and not just in a technical note. I
> think some place around host setup makes sense, We have a Host dialog Kernel
> tab where we have such things like passthrough setup, this is similar.


Ack. We should have it listed in the section where we have the TP and deprecated features listed - and we should have it in the section where we describe the hook in addition.

> 
> no API. No further configuration besides the hook

Comment 6 Rolfe Dlugy-Hegwer 2020-09-28 23:33:25 UTC

*** This bug has been marked as a duplicate of bug 1759205 ***