[Bug 2112578] Re: riscv64: KVM does not release harts

I built upstream kernel 6.14.9 with above matches. They solve my
problem.

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https://bugs.launchpad.net/bugs/2112578

Title:
riscv64: KVM does not release harts

Status in linux package in Ubuntu:
New
Status in qemu package in Ubuntu:
Invalid

Bug description:
In the 6.14.0-13-generic kernel there seems to be a problem with KVM.

On my amd64 machine I am running a riscv64 machine using QEMU 10 with
16 cores. Inside the VM I spin up a further machine with 2 cores. Once
KVM emulation is started the load of my amd64 machine rises to > 14/16
cores for qemu-system-riscv64. KVM seems not to release cores that
were ever used. Top in 1st VM shows 0.25 cores used for 2nd VM.

The usage on my amd64 machine only drops when unloading the kvm module in the first VM.
---
ProblemType: Bug
ApportVersion: 2.32.0-0ubuntu5
Architecture: riscv64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC0: zfsdt 2105 F.... wireplumber
/dev/snd/seq: zfsdt 2103 F.... pipewire
CasperMD5json:
{
"result": "skip"
}
CurrentDesktop: XFCE
DistroRelease: Ubuntu 25.10
InstallationDate: Installed on 2025-03-17 (80 days ago)
InstallationMedia: Ubuntu-Server 25.04 "Plucky Puffin" - Daily riscv64 (20250316)
Lsusb:
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 0627:0001 Adomax Technology Co., Ltd QEMU Tablet
Bus 001 Device 003: ID 0627:0001 Adomax Technology Co., Ltd QEMU Tablet
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
MachineType: QEMU QEMU Virtual Machine
Package: linux (not installed)
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
ProcFB: 0 virtio_gpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.14.0-13-generic root=UUID=af336ba2-ea81-4dd5-bada-b3e8e7fb1c58 ro crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
ProcVersionSignature: Ubuntu 6.14.0-13.13.2-generic 6.14.0
PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon.
RelatedPackageVersions:
linux-restricted-modules-6.14.0-13-generic N/A
linux-backports-modules-6.14.0-13-generic N/A
linux-firmware 20250317.git1d4c88ee-0ubuntu1
RfKill:

Tags: questing
Uname: Linux 6.14.0-13-generic riscv64
UpgradeStatus: Upgraded to questing on 2025-05-17 (19 days ago)
UserGroups: N/A
_MarkForUpload: True
acpidump:

dmi.bios.date: 05/13/2025
dmi.bios.release: 0.0
dmi.bios.vendor: Ubuntu distribution of EDK II
dmi.bios.version: 2025.02-8
dmi.chassis.type: 1
dmi.chassis.vendor: QEMU
dmi.chassis.version: virt
dmi.modalias: dmi:bvnUbuntudistributionofEDKII:bvr2025.02-8:bd05/13/2025:br0.0:svnQEMU:pnQEMUVirtualMachine:pvrvirt:cvnQEMU:ct1:cvrvirt:sku:
dmi.product.name: QEMU Virtual Machine
dmi.product.version: virt
dmi.sys.vendor: QEMU

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