kvm_s390_cpus_to_pv(9)

💖 kvm_s390_cpus_to_pv(9) 💖

okay bestie, welcome to the Kernel API Manual — yes this is a real function name and yes it's a whole mouthful, we love that for us. it's kvm_s390_cpus_to_pv, and it's lowkey the glow-up button for vCPUs ✨

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🌸 NAME 🌸

kvm_s390_cpus_to_pv — converts all the non-protected vCPUs in a protected VM into protected ones. like a makeover but for virtual CPUs, no cap 💅

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🎀 SYNOPSIS 🎀

int kvm_s390_cpus_to_pv (struct kvm *kvm , u16 *rc , u16 *rrc );

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🦋 ARGUMENTS 🦋

• kvm — the VM whose protected vCPUs are getting converted. it's the main character here, obviously 👑
• rc — holds the return value for the RC field of the UVC, specifically in case of error 🙈
• rrc — same energy, but for the RRC field of the UVC, also in case of error. the two of them are literally a matching set 🫶

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✨ DESCRIPTION ✨

it goes in and converts everything over to protected mode. and if something goes wrong? it tries to undo the conversion in case of error. like, bestie said "nvm" and hits reverse 😭 it tries — that's the energy.

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🔥 RETURN 🔥

• 0 — slay, it worked 💖
• otherwise -EIO — it did not work, and that's the whole story 💀

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🌈 SEE ALSO 🌈

go peek at the kernel file ./arch/s390/kvm/s390/s390.c — that's where the magic lives 🧚

and these iconic siblings, all in the (9) section:

• kvm_s390_update_topology_change_report(9)
• kvm_s390_cpus_from_pv(9)
• kvm_arch_vcpu_pre_fault_memory(9)
• kvm_test_age_gfn(9)
• kvm_age_gfn(9)
• kvm_unmap_gfn_range(9)

iykyk 🍓

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fr fr, double-check your pointers before you call this — rc and rrc are there for the error case and you'll want them filled in properly.

okay that's the whole page, love u, go forth and convert those vCPUs 💜

sign-off time: this one came from ./arch/s390/kvm/s390, dated October 2026, and it's kvm_s390_cpus_to_pv(9) in the Kernel API Manual — take care of her 🎀🌟