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Re: Core dump happened when starting a VM on arm64 server
From: |
Andrew Jones |
Subject: |
Re: Core dump happened when starting a VM on arm64 server |
Date: |
Thu, 11 Jun 2020 11:14:19 +0200 |
On Thu, Jun 11, 2020 at 04:46:45PM +0800, Haibo Xu wrote:
> Hi,
>
> I met a qemu core dump issue when starting a VM with cpu feature
> "pmu=on" on an arm server.
> The commands to start the machine is:
>
> ./qemu-system-aarch64 \
> -cpu host,pmu=on -M virt,accel=kvm,gic-version=3 -nographic
> -m 2048M \
> -kernel ./Image \
> -initrd /boot/initrd.img-5.6.0-rc2+ \
> -append "root=/dev/vda rw console=ttyAMA0" -nodefaults -serial
> stdio\
> -drive if=none,file=./xenial.rootfs.ext4,id=hd0,format=raw \
> -device virtio-blk-device,drive=hd0
>
>
> And here is the stack dump:
>
> Core was generated by `./qemu-system-aarch64 -cpu host,pmu=on -M
> virt,accel=kvm,gic-version=3 -nograph'.
> Program terminated with signal SIGSEGV, Segmentation fault.
> #0 kvm_ioctl (s=0x0, type=type@entry=44547) at
s=0x0 means cpu->kvm_state is NULL
> The root cause is in the arm_get_pmu() operation which was introduced
> in ae502508f83.
Actually the root cause is d70c996df23f ("target/arm/kvm: Use
CPUState::kvm_state in kvm_arm_pmu_supported()"). ae502508f83 used
the machine kvm_state, not the cpu kvm_state, and that allows pmu=on
to work. d70c996df23f changed that saying that "KVMState is already
accessible via CPUState::kvm_state, use it.", but I'm not sure why,
since kvm_init_vcpu() doesn't run until the vcpu thread is created.
Philippe?
Thanks,
drew