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Bug 1851247 - Interface for querying supported HyperV Enlightenments
Summary: Interface for querying supported HyperV Enlightenments
Keywords:
Status: CLOSED CURRENTRELEASE
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: qemu-kvm
Version: unspecified
Hardware: Unspecified
OS: Unspecified
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Vitaly Kuznetsov
QA Contact: menli@redhat.com
URL:
Whiteboard:
Depends On: 1997408
Blocks: 1624786 1717611
TreeView+ depends on / blocked
 
Reported: 2020-06-25 21:54 UTC by Eduardo Habkost
Modified: 2022-03-16 04:53 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2021-12-25 07:26:57 UTC
Type: Feature Request
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)

Description Eduardo Habkost 2020-06-25 21:54:22 UTC 
This bug was initially created as a copy of libvirt Bug #1717611.  qemu-kvm doesn't provide this information, so we need to implement an interface that libvirt can use to query hyperv enlightenments supported by the host.

I suggest using the existing CPU feature query interface for this (query-cpu-model-expansion type=full with model="host" and model="max").

Original bug #1717611 description:

Management software needs to be able to query which HyperV Enlightenments are supported by the current host.  The availability of HyperV Enlightenments depends on capabilities available in the KVM kernel module, in QEMU, and in libvirt.
Comment 1 Eduardo Habkost 2020-06-25 21:59:44 UTC 
This is supposed to work, but doesn't seem to work today:

  query-cpu-model-expansion type=full model={"name":"host","props":{"hv-passthrough":true}}

Probably because hv_cpuid_check_and_set() isn't called at feature expansion time.
Comment 2 John Ferlan 2020-07-03 12:48:37 UTC 
Rick - this seems like something Vitaly would handle - although perhaps the component/sub-subcomponent/pool would need to be adjusted.
Comment 6 Vitaly Kuznetsov 2020-09-04 15:09:48 UTC 
Upstream work started.

KVM patches suggested:
https://lore.kernel.org/kvm/20200807083946.377654-1-vkuznets@redhat.com/

QEMU patches suggested:
https://lists.gnu.org/archive/html/qemu-devel/2020-09/msg02017.html
Comment 9 Vitaly Kuznetsov 2021-07-16 14:09:34 UTC 
We have all the required bits upstream but the series is quite big and I was wondering if it would make sense to try to backport this for 8.5 or not.

Eduardo, are you aware of any particular users of this new interface? In particular, do you know if libvirt is working on a related feature?
Comment 10 Eduardo Habkost 2021-07-16 16:52:32 UTC 
(In reply to Vitaly Kuznetsov from comment #9)
> We have all the required bits upstream but the series is quite big and I was
> wondering if it would make sense to try to backport this for 8.5 or not.
> 
> Eduardo, are you aware of any particular users of this new interface? In
> particular, do you know if libvirt is working on a related feature?

I don't think we need it in 8.5.  We were not planning to use this interface in 8.5 because we thought the hyperv=on boolean (bug 1877467) would work for us.

The libvirt side of this feature is being tracked at bug 1717611.
Comment 11 Vitaly Kuznetsov 2021-07-19 07:52:14 UTC 
(In reply to Eduardo Habkost from comment #10)
> 
> I don't think we need it in 8.5.  We were not planning to use this interface
> in 8.5 because we thought the hyperv=on boolean (bug 1877467) would work for
> us.

OK, I'm not backporting patches then, we'll get them with the next rebase. Thanks!
Comment 12 John Ferlan 2021-09-09 13:32:34 UTC 
Bulk update: Move RHEL-AV bugs to RHEL9. If necessary to resolve in RHEL8, then clone to the current RHEL8 release.
Comment 13 menli@redhat.com 2021-11-25 06:06:04 UTC 
Hi Vitaly，

Whether we could move this bug to modify status, as it already works on qemu 6.1. or still wait for other related patch?

details:
qemp command:
{ "execute":"query-cpu-model-expansion","arguments":{"type":"full","model":{"name":"host","props":{"hv-passthrough":true}}}}

test on qemu-kvm-6.1.0-1.module+el8.6.0+12721+8d053ff2.x86_64 before, the result is like: '.."hv-relaxed": true, "avx512-fp16": false, "hv-crash": true,..'
also try it on qemu-kvm-4.2.0-59.module+el8.5.0+12817+cb650d43.x86_64 , the result is like: '.."hv-relaxed": false, "hv-crash": false..'

Thanks
Menghuan
Comment 15 Vitaly Kuznetsov 2021-11-25 10:06:37 UTC 
(In reply to menli from comment #13)
> Hi Vitaly，
> 
> Whether we could move this bug to modify status, as it already works on qemu
> 6.1.

Yes, let's make this TestOnly dependent on QEMU rebase to 6.1 BZ and move to ON_QA.
Comment 16 menli@redhat.com 2021-11-25 10:59:03 UTC 
Base on comment 13 and comment 15, change status to verified.
Comment 17 RHEL Program Management 2021-12-25 07:26:57 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.
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