dat_perform_essa(9)

💅 dat_perform_essa(9) — Kernel API Manual

okay so bestie, welcome to dat_perform_essa(9) from the Kernel API Manual ✨ this is the one that does the ESSA actions on the PGSTE, and honestly it's giving main character energy in the s390 KVM gmap world 🦋

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✨ NAME ✨

dat_perform_essa — Perform ESSA actions on the PGSTE. that's it, that's the whole vibe 💅

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🌸 SYNOPSIS 🌸

int dat_perform_essa (union asce asce , gfn_t gfn , int orc , union
       essa_state *state , bool *dirty );

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🎀 ARGUMENTS 🎀

• asce — the asce you're operating on, like this is the thing we're doing the whole moment for 💖
• gfn — the guest page frame to operate on. yes, that guest page frame 🫶
• orc — the specific action to perform, bestie. which one? check the ESSA_SET_* macros, that's where the tea is 🍓
• state — the storage attributes that get returned to the guest ✨
• dirty — returns whether the function dirtied a previously clean entry 👀 lowkey important

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💜 CONTEXT 💜

called with kvm->mmu_lock held. no cap, that's a requirement, not a suggestion 🔥

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⭐ RETURN ⭐

• 1 — if the page state has been altered and the page is to be added to the CBRL 👑
• 0 — if the page state has been altered, but the page is not to be added to the CBRL 🌈
• -1 — if the page state has not been altered and the page is not to be added to the CBRL 💀

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🦋 SEE ALSO 🦋

Kernel file ./arch/s390/kvm/gmap/dat.c — and the whole squad fr fr:

• dat_crstep_xchg_atomic(9)
• dat_entry_walk(9)
• _dat_walk_gfn_range(9)
• dat_test_age_gfn(9)
• dat_set_cmma_bits(9)

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okay that's the whole page, mwah 💋 this lives in ./arch/s390/kvm/gmap and it's stamped October 2026 — iykyk 🧚💜