Bug 1856515

Summary:	Some versions of CPU models are not usable by existing software
Product:	Red Hat Enterprise Linux 9	Reporter:	Eduardo Habkost <ehabkost>
Component:	libvirt	Assignee:	Tim Wiederhake <twiederh>
libvirt sub component:	General	QA Contact:	Luyao Huang <lhuang>
Status:	CLOSED DEFERRED	Docs Contact:
Severity:	unspecified
Priority:	unspecified	CC:	ailan, dyuan, jdenemar, jsuchane, kchamart, lhuang, lmen, virt-maint, xuzhang, yalzhang
Version:	unspecified	Keywords:	FutureFeature, Reopened, Triaged
Target Milestone:	rc	Flags:	pm-rhel: mirror+
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2023-07-12 09:50:56 UTC	Type:	Feature Request
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	1856522, 1942888

Description Eduardo Habkost 2020-07-13 19:48:13 UTC

We are introducing new APIs to retrieve information about CPU model versions (bz#1697663 and bz#1727122), but existing software that is not using the new API should be able to use new versions of CPU models (because sometimes the new CPU models contain important bug fixes).

Example of cases where new versions of CPU models are bug fixes, and need to be available through libvirt even if not using the CPU model versioning API:

* Icelake-Server-v3 (with ARCH_CAPABILITIES support added) (bug 1840386)
* Icelake-Server-v4 (missing features added, including but not limited to VMX caps)
* Denverton-v2 (MPX removed)
* Snowridge-v2 (MPX removed)
* Skylake-Server-v4 (VMX feature list fix)
* Cascadelake-Server-v4 (missing VMX capability added)
* EPYC-v3 (missing features added: perfctr-core, clzero, xsaveptr, xsaves)

The other existing versioned CPU models seem to have their aliases added to libvirt's cpu_map (for example: libvirt doesn't have Broadwell-v4, but it has Broadwell-noTSX-IBRS).  Maybe it would be useful to expose the -v1/-v2/-v3/etc names through the libvirt API too (in addition to the aliases) for consistency, but that's a design choice left for the libvirt developers.

Comment 2 Eduardo Habkost 2021-04-07 19:21:00 UTC

This is necessary to address issues like the one reported at bug 1942888.  Are there plans to address it soon?

Note that this is independent from the ongoing work to support resolving CPU model aliases and selecting the last version automatically (bug 1697663).

Comment 3 Jiri Denemark 2021-04-27 10:05:47 UTC

Sure, this is planned for the next RHEL release. I already have ideas
answering most questions I need to solve to implement this.

However it would be nice if it go in together with full support for CPU
versions even though it doesn't depend on it.

Comment 4 John Ferlan 2021-09-09 15:50:35 UTC

Bulk update: Move RHEL-AV bugs to RHEL8.

Added RHV to Dependent Product to match bug 1856522 (and others). If Resolution/Testing is required for RHEL9, then a clone must be created.

Comment 6 RHEL Program Management 2022-01-13 07:27:59 UTC

After evaluating this issue, there are no plans to address it further or fix it in an upcoming release.  Therefore, it is being closed.  If plans change such that this issue will be fixed in an upcoming release, then the bug can be reopened.

Comment 9 John Ferlan 2022-09-02 19:34:28 UTC

Moving to RHEL9 to match blocked bugs. Removed RHV as Dependent Product since that is not supported there.

Comment 13 Jaroslav Suchanek 2023-07-12 09:50:56 UTC

Lets close this one correspondingly to qemu-kvm counterpart (bug 1697663). We will create new set of feature requests, once we get better understanding of what is actually the desired goal and how to implement it through the stack. Thanks.