RE: [PATCH RFC V3 00/29] Support of Virtual CPU Hotplug for ARMv8 Arch

[Salil Mehta]

Hi Gavin,

Thanks for further information.

>  From: Gavin Shan <gshan@redhat.com>
>  Sent: Thursday, August 8, 2024 12:41 AM
>  To: Salil Mehta <salil.mehta@huawei.com>; qemu-devel@nongnu.org;
>  qemu-arm@nongnu.org; mst@redhat.com
>  
>  Hi Salil,
>  
>  On 8/7/24 11:27 PM, Salil Mehta wrote:
>  >
>  > Let me figure out this. Have you also included the below patch along
>  > with the architecture agnostic patch-set accepted in this Qemu cycle?
>  >
>  > https://lore.kernel.org/all/20240801142322.3948866-3-peter.maydell@lin
>  > aro.org/
>  >
>  
>  There are no vCPU fd to be parked and unparked when the core dump
>  happenes. I tried it, but didn't help. I added more debugging messages and
>  the core dump is triggered in the following path. It seems 'cpu-
>  >sve_vq.map' isn't correct since it's populated in CPU realization path, and
>  those non-cold-booted CPUs aren't realized in the booting stage.


Ah, I've to fix the SVE support. I'm already working on it and will be part of
the RFC V4.

Have you tried booting VM by disabling the SVE support?


>  
>  # dmesg | grep "Scalable Vector Extension"
>  [    0.117121] CPU features: detected: Scalable Vector Extension
>  
>  # start_vm
>  ===> machvirt_init: create CPU object (idx=0, type=[host-arm-cpu])
>  cpu_common_initfn arm_cpu_initfn aarch64_cpu_initfn
>  aarch64_cpu_instance_init aarch64_host_initfn arm_cpu_post_init ===>
>  machvirt_init: realize CPU object (idx=0) virt_cpu_pre_plug
>  arm_cpu_realizefn cpu_common_realizefn virt_cpu_plug ===>
>  machvirt_init: create CPU object (idx=1, type=[host-arm-cpu])
>  cpu_common_initfn arm_cpu_initfn aarch64_cpu_initfn
>  aarch64_cpu_instance_init aarch64_host_initfn arm_cpu_post_init
>  kvm_arch_init_vcpu: Error -22 from kvm_arm_sve_set_vls()
>  qemu-system-aarch64: Failed to initialize host vcpu 1 Aborted (core
>  dumped)

Yes, sure. 

Thanks
Salil.


>  
>  Thanks,
>  Gavin
>  
>  >>
>  >>   With this series and latest upstream Linux kernel (host), I ran into 
> core
>  >>   dump as below.
>  >>   I'm not sure if it's a known issue or not.
>  >>
>  >>   # uname -r
>  >>   6.11.0-rc2-gavin+
>  >>   # /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64 -
>  accel
>  >>   kvm \
>  >>      -machine virt,gic-version=host,nvdimm=on -cpu host                 \
>  >>      -smp maxcpus=2,cpus=1,sockets=2,clusters=1,cores=1,threads=1       \
>  >>      -m 4096M,slots=16,maxmem=128G                                      \
>  >>      -object memory-backend-ram,id=mem0,size=2048M                      \
>  >>      -object memory-backend-ram,id=mem1,size=2048M                      \
>  >>      -numa node,nodeid=0,memdev=mem0,cpus=0-0                           \
>  >>      -numa node,nodeid=1,memdev=mem1,cpus=1-1                           \
>  >>        :
>  >>   qemu-system-aarch64: Failed to initialize host vcpu 1 Aborted (core
>  >>   dumped)
>  >>
>  >>   # gdb /var/lib/systemd/coredump/core.0
>  >>   /home/gavin/sandbox/qemu.main/build/qemu-system-aarch64
>  >>   (gdb) bt
>  >>   #0  0x0000ffff9eec42e8 in __pthread_kill_implementation () at
>  >>   /lib64/libc.so.6
>  >>   #1  0x0000ffff9ee7c73c in raise () at /lib64/libc.so.6
>  >>   #2  0x0000ffff9ee69034 in abort () at /lib64/libc.so.6
>  >>   #3  0x0000aaaac71152c0 in kvm_arm_create_host_vcpu
>  >>   (cpu=0xaaaae4c0cb80)
>  >>        at ../target/arm/kvm.c:1093
>  >>   #4  0x0000aaaac7057520 in machvirt_init (machine=0xaaaae48198c0) at
>  >>   ../hw/arm/virt.c:2534
>  >>   #5  0x0000aaaac6b0d31c in machine_run_board_init
>  >>        (machine=0xaaaae48198c0, mem_path=0x0, errp=0xfffff754ee38) at
>  >>   ../hw/core/machine.c:1576
>  >>   #6  0x0000aaaac6f58d70 in qemu_init_board () at ../system/vl.c:2620
>  >>   #7  0x0000aaaac6f590dc in qmp_x_exit_preconfig
>  (errp=0xaaaac8911120
>  >>   <error_fatal>)
>  >>        at ../system/vl.c:2712
>  >>   #8  0x0000aaaac6f5b728 in qemu_init (argc=82, argv=0xfffff754f1d8) at
>  >>   ../system/vl.c:3758
>  >>   #9  0x0000aaaac6a5315c in main (argc=82, argv=0xfffff754f1d8) at
>  >>   ../system/main.c:47
>  >>
>  >>   Thanks,
>  >>   Gavin
>  >>
>  >
>