Bug 1895204
| Summary: | RFE: support cpu feature kvm-poll-control | ||
|---|---|---|---|
| Product: | Red Hat Enterprise Linux Advanced Virtualization | Reporter: | Han Han <hhan> |
| Component: | libvirt | Assignee: | Tim Wiederhake <twiederh> |
| Status: | CLOSED ERRATA | QA Contact: | Luyao Huang <lhuang> |
| Severity: | medium | Docs Contact: | |
| Priority: | medium | ||
| Version: | 8.4 | CC: | chhu, dyuan, jdenemar, jinqi, jsuchane, lhuang, lmen, virt-maint, xuzhang, yalzhang |
| Target Milestone: | rc | Keywords: | FutureFeature, Triaged |
| Target Release: | 8.3 | ||
| Hardware: | Unspecified | ||
| OS: | Unspecified | ||
| Whiteboard: | |||
| Fixed In Version: | libvirt-6.10.0-1.el8 | Doc Type: | If docs needed, set a value |
| Doc Text: | Story Points: | --- | |
| Clone Of: | Environment: | ||
| Last Closed: | 2021-05-25 06:45:10 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: | 6.10.0 |
| Embargoed: | |||
merged upstream: https://gitlab.com/libvirt/libvirt/-/commit/ea21b8b87b9ae72d0d9ebab10a1c5b1480f5a16a Verify this bug with libvirt-daemon-6.10.0-1.module+el8.4.0+8898+a84e86e1.x86_64:
S1: Start guest with cpu feature kvm-poll-control
1. enable poll-control in guest xml:
# virsh dumpxml vm1 --inactive
..
<features>
<acpi/>
<apic/>
<pae/>
<kvm>
<poll-control state='on'/>
</kvm>
</features>
..
2. start guest
# virsh start vm1
Domain vm1 started
3. check qemu command line:
# ps uax|grep qemu
...,kvm-poll-control=on...
4. destroy guest
# virsh destroy vm1
Domain vm1 destroyed
5. disable poll-control in guest xml:
<features>
<acpi/>
<apic/>
<pae/>
<kvm>
<poll-control state='off'/>
</kvm>
</features>
6. start guest
# virsh start vm1
Domain vm1 started
7. check qemu command line and there is no kvm-poll-control:
# ps aux|grep qemu |grep kvm-poll-control
# echo $?
1
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 (virt:av bug fix and enhancement update), 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-2021:2098 |
Description of problem: The kvm halt poll control support has been introduced since QEMU v4.2: commit d645e13287 Author: Marcelo Tosatti <mtosatti> Date: Mon Jun 3 20:04:08 2019 -0300 kvm: i386: halt poll control MSR support Add support for halt poll control MSR: save/restore, migration and new feature name. The purpose of this MSR is to allow the guest to disable host halt poll. Signed-off-by: Marcelo Tosatti <mtosatti> Message-Id: <20190603230408.GA7938> [Do not enable by default, as pointed out by Mark Kanda. - Paolo] Signed-off-by: Paolo Bonzini <pbonzini> And guest kernel v5.4: commit fa86ee90eb11 Author: Marcelo Tosatti <mtosatti> Date: Wed Jul 3 20:51:25 2019 -0300 add cpuidle-haltpoll driver Add a cpuidle driver that calls the architecture default_idle routine. To be used in conjunction with the haltpoll governor. Signed-off-by: Marcelo Tosatti <mtosatti> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki> It will help improve performance for virtualized guests(See p18 of Stefan Hajnoczi's Optimizing for NVMe Drives: https://vmsplice.net/~stefan/stefanha-kvm-forum-2020.pdf) Expected cpu xml: <cpu ...> <feature policy='require' name='kvm-poll-control'/> </cpu> Current status in libvirt: ➜ ~ virsh start fedora31 error: Failed to start domain fedora31 error: unsupported configuration: unknown CPU feature: kvm-poll-control