kvm_s390_pv_set_aside(9)

💅 kvm_s390_pv_set_aside — bestie's guide to parking a protected VM

okay so this is kvm_s390_pv_set_aside(9) from the Kernel API Manual, and honestly it's one of those little functions that does so much heavy lifting. Let's get into it 🫶

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🌸 NAME 🌸

kvm_s390_pv_set_aside — literally just sets aside a protected VM so you can tear it down later. That's the whole vibe check. ✨

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🎀 SYNOPSIS 🎀

int kvm_s390_pv_set_aside (struct kvm *kvm , u16 *rc , u16 *rrc );

like, copy that exactly, don't @ me 🙈

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🦋 ARGUMENTS 🦋

• kvm — the VM. the main character, if you will 👑
• rc — the return value for the RC field of the UVCB. very demure, very mindful, just holding that value for you 💅
• rrc — the return value for the RRC field of the UVCB. same energy, different field 🍓

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💖 DESCRIPTION 💖

so what this does is set aside the protected VM for a subsequent teardown — like putting it on hold, no cap. Best part? The VM is able to continue immediately as a non-secure VM. iconic behaviour honestly 😭 And the info you need to properly tear down the protected VM? all set aside, neatly, for later. so organized.

but here's the catch bestie: if another protected VM was already set aside and nobody started its teardown yet, this function will fail. it's giving one-at-a-time, no shortcuts. ⚠️

also, real talk — the CPUs of the protected VM need to be destroyed beforehand. like, before you call this. don't skip that step, fr fr 💀

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🔥 CONTEXT 🔥

kvm->lock needs to be held. yes, you actually have to hold the lock. this is not a drill 🫠

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⭐ RETURN ⭐

• 0 — slay, it worked. success 🎉
• -EINVAL — nope, another protected VM was already set aside 🙈
• -ENOMEM — the system ran out of memory. budget said no 😭

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🌈 SEE ALSO 🌈

• Kernel file ./arch/s390/kvm/s390/pv.c — should_export_before_import(9)
• kvm_s390_pv_make_secure(9)
• kvm_s390_pv_destroy_page(9)
• struct pv_vm_to_be_destroyed(9)
• kvm_s390_pv_dispose_one_leftover(9)
• kvm_s390_pv_deinit_vm(9)
• kvm_s390_pv_deinit_cleanup_all(9)
• kvm_s390_pv_deinit_aside_vm(9)
• kvm_s390_pv_dump_stor_state(9)
• kvm_s390_pv_dump_complete(9)

the whole friend group, honestly 🧚 go read them too, iykyk 🦋

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tl;dr: hold kvm->lock, destroy the CPUs first, and remember only one protected VM can be set aside at a time. the way that this function has RULES. 💅

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and that's the page bestie! 🎀 this one comes from ./arch/s390/kvm/s390, dated October 2026 — go off, s390 kernel devs, you absolute legends 👑✨