Hi James,
On 2/3/23 9:50 PM, James Morse wrote:
[...]
The first patch has already been posted as a fix here:
https://www.spinics.net/lists/linux-ia64/msg21920.html
I've only build tested Loongarch and ia64.
It has been merged to upstream.
If folk want to play along at home, you'll need a copy of Qemu that supports this.
https://github.com/salil-mehta/qemu.git salil/virt-cpuhp-armv8/rfc-v1-port29092022.psci.present
You'll need to fix the numbers of KVM_CAP_ARM_HVC_TO_USER and KVM_CAP_ARM_PSCI_TO_USER
to match your host kernel. Replace your '-smp' argument with something like:
| -smp cpus=1,maxcpus=3,cores=3,threads=1,sockets=1
then feed the following to the Qemu montior;
| (qemu) device_add driver=host-arm-cpu,core-id=1,id=cpu1
| (qemu) device_del cpu1
This series is based on v6.2-rc3, and can be retrieved from:
https://git.kernel.org/pub/scm/linux/kernel/git/morse/linux.git/ virtual_cpu_hotplug/rfc/v1
I give it a try, but the hot-added CPU needs to be put into online
state manually. I'm not sure if it's expected or not.
/home/gavin/sandbox/qemu.main/build/qemu-system-aarch64 \
-accel kvm,dirty-ring-size=65536 \
-machine virt,gic-version=host,nvdimm=on \
-cpu host -smp maxcpus=8,cpus=1,sockets=1,clusters=1,cores=8,threads=1 \
-m 1024M,slots=16,maxmem=64G \
-object memory-backend-ram,id=mem0,size=1024M \
-numa node,nodeid=0,memdev=mem0 \
-L /home/gavin/sandbox/qemu.main/build/pc-bios \
-monitor none -serial mon:stdio -nographic -gdb tcp::1234 \
-bios /home/gavin/sandbox/qemu.main/build/pc-bios/edk2-aarch64-code.fd \
-kernel /home/gavin/sandbox/linux.guest/arch/arm64/boot/Image \
-initrd /home/gavin/sandbox/images/rootfs.cpio.xz \
-append memhp_default_state=online_movable \
:
:
guest# cat /proc/cpuinfo | grep "CPU implementer" | wc -l
1
(qemu) device_add driver=host-arm-cpu,core-id=1,id=cpu1
guest# cat /proc/cpuinfo | grep "CPU implementer" | wc -l
1
guest# echo 1 > /sys/devices/system/cpu/cpu1/online
guest# cat /proc/cpuinfo | grep "CPU implementer" | wc -l
2
(qemu) device_del cpu1
guest# cat /proc/cpuinfo | grep "CPU implementer" | wc -l
1
Note that the QEMU binary is directly built from Salil's repository and
the kernel image is built from v6.3-rc4, plus this patchset excluding the
first patch since it has been merged.
Thanks,
Gavin
