virtio-fs: wake the VMM when the guest reports an exit code#610
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virtio-fs: wake the VMM when the guest reports an exit code#610yzewei wants to merge 1 commit intocontainers:mainfrom
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When a virtual machine (VM) passes its final exit status via the `KRUN_EXIT_CODE_IOCTL` function on the virtio-fs root filesystem, the host records it in the shared `exit_code` AtomicI32, but does not signal it to the VMM's `EventFd`. The VMM only stops when `exit_evt` becomes readable, so the VM's reported exit status itself does not wake up the `EventManager` and terminate the VM. This is a common bug in virtio-fs/VMM exit interactions, not a code path specific to any particular architecture (but the reset path on x86-64 i8042 is configured as a VMM exit event, masking the problem). User-visible symptoms depend on the architecture/platform: - On platforms without an equivalent rollback mechanism, or where the VM continues to perform reboot/shutdown processing after reporting the exit code, it may continue running even after reporting completion. We observed the latter scenario on LoongArch, where the virtual machine could continue to restart/shut down, eventually leading to a soft lock rather than the VMM exiting immediately. Signed-off-by: Zewei Yang <yangzewei@loongson.cn>
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When a virtual machine (VM) passes its final exit status via the
KRUN_EXIT_CODE_IOCTLfunction on the virtio-fs root filesystem, the host records it in the sharedexit_codeAtomicI32, but does not signal it to the VMM'sEventFd.The VMM only stops when
exit_evtbecomes readable, so the VM's reported exit status itself does not wake up theEventManagerand terminate the VM.This is a common bug in virtio-fs/VMM exit interactions, not a code path specific to any particular architecture (but the reset path on x86-64 i8042 is configured as a VMM exit event, masking the problem). User-visible symptoms depend on the architecture/platform:
We observed the latter scenario on LoongArch, where the virtual machine could continue to restart/shut down, eventually leading to a soft lock rather than the VMM exiting immediately.