kvm_s390_inject_prog_cond(9)

💅 kvm_s390_inject_prog_cond(9) — the Kernel API Manual page your group chat needed

okay so bestie, welcome to the Kernel API Manual entry for kvm_s390_inject_prog_cond — a function name so long it's basically its own vibe 💀 but don't run, it's actually lowkey adorable once you get what it does. It conditionally injects a program check, and "conditionally" is doing so much work in that sentence, iykyk.

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✨ NAME ✨

kvm_s390_inject_prog_cond — conditionally inject a program check 🎀

🌸 SYNOPSIS 🌸

int kvm_s390_inject_prog_cond (struct kvm_vcpu *vcpu , int rc );

🦋 ARGUMENTS 🦋

• vcpu — the virtual cpu in question, the main character of this whole operation 👑
• rc — the original return/error code, i.e. the receipts from whatever just happened 🧾

💖 DESCRIPTION 💖

So here's the lore: this function is supposed to be used after regular guest access functions failed, and its whole job is to conditionally inject a program check to a vcpu. Not always — conditionally. That distinction is literally the entire point, bestie, don't skip it 🙈

The typical pattern looks like this:

rc = write_guest(vcpu, addr, data, len); if (rc) return kvm_s390_inject_prog_cond(vcpu, rc);

Now the part where you have to actually pay attention 🔥 A negative return code from guest access functions implies an internal error, like e.g. out of memory. When that happens, no program check should be injected to the guest — hard no, do not pass go, do not inject. 🙅‍♀️

A positive value, on the other hand, implies that an exception happened while accessing a guest's memory. In that case, all the data belonging to the corresponding program check has already been stored in vcpu->arch.pgm, and it can be injected with kvm_s390_inject_prog_irq. See how it all connects? It's giving ecosystem 🫶

⭐ RETURN ⭐

• the original rc value if rc was negative (internal error) 😭
• zero if rc was already zero ✌️
• zero or error code from injecting if rc was positive (program check injected to vcpu) 💅

🌈 SEE ALSO 🌈

Kernel file ./arch/s390/kvm/s390/s390.h __kvm_s390_pv_destroy_page(9), kvm_s390_vcpu_crypto_reset_all(9), kvm_s390_vcpu_pci_enable_interp(9)

lowkey go read those too, they're in the same friend group fr fr 🍓

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and that's the whole page, bestie — no cap, you ate that 🧚 sign-off time: this lil masterpiece comes from the Kernel API Manual source at ./arch/s390/kvm/s390, dated October 2026. iconic. periodt. 💜🎀✨