setup_apcb(9)

✨ setup_apcb(9) ✨

okay so bestie, we're in the Kernel API Manual today and this one is literally about s390 crypto control blocks 💅 buckle up 🎀

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💖 NAME 💖

setup_apcb — Create a shadow copy of the apcb.

like, it makes a shadow copy. a little twin. main character energy for a data structure 🦋

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🌸 SYNOPSIS 🌸

int setup_apcb (struct kvm_vcpu *vcpu , struct kvm_s390_crypto_cb
*crycb_s , const u32 crycb_gpa , struct kvm_s390_crypto_cb *crycb_h ,
int fmt_o , int fmt_h );

that's the whole signature, no cap. six things go in, an int comes out 🔥

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🫶 ARGUMENTS 🫶

• vcpu — pointer to the virtual CPU. the little virtual guy we're doing all this for 👑
• crycb_s — pointer to shadow crycb. yes bestie, the shadow copy lives here 💜
• crycb_gpa — guest physical address of original guest crycb. like, the address where the real one is chilling 📍
• crycb_h — pointer to the host crycb. the host's own version, iconic 💅
• fmt_o — format of the original guest crycb. just the guest format, don't overthink it 🍓
• fmt_h — format of the host crycb. and this is the host's format 🌸

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🌈 DESCRIPTION 🌈

so what it actually does: it checks the compatibility between the guest and host crycb and calls the appropriate copy function. that's it, that's the vibe check ✨

Return 0 or an error number if the guest and host crycb are incompatible. 😭 like if they don't match, you get an error number back, that's the whole deal. no compatible formats, no shadow copy, periodt 💀

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🦋 SEE ALSO 🦋

• Kernel file ./arch/s390/kvm/s390/vsie.c — that's where the tea is 🫖
• setup_apcb00(9)
• setup_apcb11(9)
• shadow_crycb(9)

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and that's the page bestie, go read the friends too, iykyk 💖

signing off from ./arch/s390/kvm/s390, October 2026 — stay slay, stay compatible ⭐🎀