Bug 1851249

Summary:	Support hv-passthrough mode
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 ERRATA	Docs Contact:
Severity:	medium
Priority:	medium	CC:	dyuan, jdenemar, jsuchane, lmen, mprivozn, twiederh, virt-maint, xuzhang, yalzhang
Version:	9.0	Keywords:	AutomationBackLog, FutureFeature, Triaged
Target Milestone:	rc	Flags:	ehabkost: mirror+
Target Release:	---
Hardware:	x86_64
OS:	Unspecified
Whiteboard:
Fixed In Version:	libvirt-8.0.0-0rc1.1.el9	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2022-05-17 12:45:05 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:	8.0.0
Embargoed:

Description Eduardo Habkost 2020-06-25 22:05:25 UTC

QEMU supports a convenient CPU option for enabling all supported hyperv flags (hv-passthrough=on).

libvirt could support that flags, so management software could easily enable all supported hyperv flags out of the box when live migration support isn't required by the user.

Comment 1 Vitaly Kuznetsov 2020-06-26 14:32:27 UTC

Libvirt could also leverage hv-passthrough to figure out which Hyper-V enlightenments
are supported (for https://bugzilla.redhat.com/show_bug.cgi?id=1717611) the same way
it does with host CPU features (running QEMU with "-cpu host" and querying all supported
CPUIDs).

Comment 3 John Ferlan 2021-09-08 13:30:05 UTC

Bulk update: Move RHEL-AV bugs to RHEL9. If necessary to resolve in RHEL8, then clone to the current RHEL8 release.

Comment 5 Tim Wiederhake 2021-11-26 14:36:01 UTC

Proposed patch: https://listman.redhat.com/archives/libvir-list/2021-November/msg00861.html

Comment 6 Tim Wiederhake 2021-12-20 09:45:01 UTC

Merged upstream: https://gitlab.com/libvirt/libvirt/-/commit/8b6766bd77108dc826715a359157d113baaa6f8f

Comment 12 Luyao Huang 2022-01-17 06:38:02 UTC

Verify this bug with libvirt-8.0.0-1.el9.x86_64:

1. prepare a guest which have hv-passthrough element:

# virsh dumpxml vm1
...
  <features>
    <acpi/>
    <apic/>
    <hyperv mode='passthrough'>
    </hyperv>
  </features>
...

2. start guest

# virsh start vm1
Domain 'vm1' started


3. check qemu command line and make sure that libvirt add hv-passthrough=on in qemu command line 

# ps aux|grep qemu
... -cpu Skylake-Client-IBRS,...,hv-passthrough=on ...

Comment 14 errata-xmlrpc 2022-05-17 12:45:05 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (new packages: libvirt), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2022:2390