Implement the ability to record the exit code from the entrypoint in userspace #312
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Contributor
slp
commented
Apr 9, 2025
slp
commented
slp
requested review from
jakecorrenti,
MatiasVara,
mtjhrc and
tylerfanelli
as code owners
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Fixes #306, containers/crun#1694 and containers/crun#1688 |
nohajc
reviewed
Apr 9, 2025
mtjhrc
requested changes
Apr 10, 2025
For the container use case, we need to relay the exit code from userspace in the microVM all the way to the process using libkrun to launch the VMM. Since ioctls are passed mostly unmodified from userspace in the guest to the virtio-fs device, we can use them as a mechanism for transporting this information without requiring any specific support in the guest's kernel. Here we create an AtomicI32 and wire it up between virtio-fs and Vmm, using it as exit code if userspace has set it to some value other than i32::MAX. Otherwise, we keep using the vCPU exit code, as we did before. Signed-off-by: Sergio Lopez <[email protected]>
We already fixed this for Linux a while ago, do the same for the macOS implementation. Signed-off-by: Sergio Lopez <[email protected]>
Use the newly added exit code recording feature in virtio-fs to record the exit code from workload's entrypoint. We need to stop ignoring SIGCHLD, as otherwise waitpid doesn't record the exit code of our child, which also means we need to do a waitpid on every children to ensure we aren't leaving zombie processes. Signed-off-by: Sergio Lopez <[email protected]>
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I think I've addressed all the feedback. |
tylerfanelli
previously approved these changes
Apr 22, 2025
mtjhrc
requested changes
Apr 23, 2025
For consistency for the container isolation use case, let's use in init the same exit codes as chroot and podman do: 125: "init" cannot set up the environment inside the microVM. 126: "init" can find the executable to be run inside the microVM but cannot not execute it. 127: "init" cannot find the executable to be run inside the microVM. Co-authored-by: Matej Hrica <[email protected]> Signed-off-by: Sergio Lopez <[email protected]>
tylerfanelli
approved these changes
Apr 24, 2025
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