kvm_s390_lo...to_effective(9)

💫 kvm_s390_logical_to_effective(9) 💫

ok so we're in the Kernel API Manual today bestie, and this little function is genuinely iconic — it's the glow-up translator for s390 guest addresses. let's get into it 🎀

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✨ NAME ✨

kvm_s390_logical_to_effective — convert guest logical to effective address

like, it takes your guest's logical address and hands you back the effective one. it's giving translator era 💅

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🌸 SYNOPSIS 🌸

unsigned long kvm_s390_logical_to_effective (struct kvm_vcpu *vcpu ,
unsigned long ga );

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🦋 ARGUMENTS 🦋

• vcpu — guest virtual cpu. the main character of this whole operation 💖
• ga — guest logical address. the address we're about to makeover ✨

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👑 DESCRIPTION 👑

ok so here's the tea ☕ — this function converts a guest vcpu logical address into a guest vcpu effective address by applying the rules of the vcpu's addressing mode, and that mode is defined by PSW bits 31 and 32 (extendended/basic addressing mode). yes bestie, the addressing mode lives in the PSW, that's just how it is 🫶

and depending on what addressing mode the vcpu is in, some of those upper bits of ga get zeroed out, and whatever's left is what you get back:

• upper 40 bits get zeroed in 24 bit addressing mode 💀
• upper 33 bits get zeroed in 31 bit addressing mode 🌈
• no bits get zeroed in 64 bit addressing mode — full address, no notes, main character energy 👑

the remaining bits are returned. periodt. 🎀

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💜 SEE ALSO 💜

Kernel file ./arch/s390/kvm/s390/gaccess.h, plus the whole friend group:

• kvm_s390_real_to_abs(9)
• _kvm_s390_logical_to_effective(9)
• put_guest_lc(9)
• write_guest_lc(9)
• read_guest_lc(9)
• write_guest_with_key(9)
• write_guest(9)
• read_guest_with_key(9)
• read_guest(9)
• read_guest_instr(9)
• write_guest_abs(9)
• read_guest_abs(9)
• write_guest_real(9)
• read_guest_real(9)

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💫 and that's the whole page, bestie 💫

this little gem lives in ./arch/s390/kvm/s390, dropped October 2026, and it answers to the name kvm_s390_lo...to_effective(9) (yes the header truncates it like that, we don't make the rules 😭). mwah, go zero some bits responsibly 🍓🧚💜