Bug 2225347

Summary:	Document that the Guest OS must support the vCPU model and features provided by the Host
Product:	Red Hat Enterprise Linux 9	Reporter:	Germano Veit Michel <gveitmic>
Component:	Documentation	Assignee:	Jiri Herrmann <jherrman>
Documentation sub component:	default	QA Contact:	RHEL DPM <rhel-docs>
Status:	CLOSED CURRENTRELEASE	Docs Contact:
Severity:	medium
Priority:	high	CC:	davozeni, myamazak, nanliu, radrao, rhel-docs
Version:	9.2	Keywords:	Documentation, FutureFeature
Target Milestone:	rc
Target Release:	---
Hardware:	x86_64
OS:	Linux
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Fixed In Version:		Doc Type:	If docs needed, set a value
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Last Closed:	2023-08-07 13:24:35 UTC	Type:	Bug
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Documentation:	---	CRM:
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
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Description Germano Veit Michel 2023-07-25 03:54:43 UTC

Document URL: 
https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/9/html/configuring_and_managing_virtualization/assembly_creating-virtual-machines_configuring-and-managing-virtualization

Section Number and Name: 
Chapter 3. Creating virtual machines

Describe the issue: 

Assume the following scenario:

Host OS:  RHEL9, supports CPU models X Y Z from Vendor A
Guest OS: RHEL7, only supports CPU models X and Y from Vendor A

If the hardware has model Z (assume a newer model released after hardware enablement for RHEL7 finished), it is possible to configure the VM with a cpu-model of Z, or with host-model or passthrough, all of which will expose CPU features to the Guest OS that its OS may not be able to handle properly. This is not tested, and may produce undesired results.

Suggestions for improvement: 

Document that the Guest OS version must also support the CPU model and features defined in the Guest XML, when creating/editing a VM, not just the Host OS.

Certified CPUs by RHEL version can be found at https://catalog.redhat.com/hardware/search?type=Component|CPU%20Collection&p=1

Comment 2 Germano Veit Michel 2023-07-25 03:55:28 UTC

I suggest to add it to the "Creating VMs" chapter, but feel to document in a more suitable location.

Comment 3 radrao 2023-07-25 08:12:30 UTC

Annotation: Chapter 3. Creating virtual machines of the "Configuring and managing virtualization" title. 

Suggestion to add content to the "Creating VMs" chapter.