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

[Gavin Shan]

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?
>
> 20240801142322.3948866-3-peter.maydell@linaro.org/">https://lore.kernel.org/all/20240801142322.3948866-3-peter.maydell@linaro.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.

# 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)

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
> >