crste_needs_unshadow(9)

🎀 NAME 🎀

okay bestie, welcome to crste_needs_unshadow(9) from the Kernel API Manual 🫶 this is the little helper that checks if the crste operations triggers unshadowing. yes, that's the whole vibe ✨

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🦋 SYNOPSIS 🦋

bool crste_needs_unshadow (union crste oldcrste , union crste newcrste );

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💖 ARGUMENTS 💖

• oldcrste — the previous value for the crste. the before pic 📸
• newcrste — the new value for the crste. the glow-up pic ✨

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🔥 DESCRIPTION 🔥

so here's the tea ☕ if the old crste did not have the vsie_notif bit set, return false: the page is not involved in vsie and thus should not trigger an unshadow operation. lowkey minding its own business 💅

conversely, if the bit is set, it can only be g3 memory, since dat tables are never mapped using large pages. that's just how it is, no cap 🧚

similar to the pgste.vsie_gmem case of pte_needs_unshadow, if the protection bit is changing or the new page is invalid, trigger an unshadow event. also trigger an unshadow event if the new crste does not have the vsie_notif bit set. it's giving "watch out, something's shifting" 👀🔥

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🌈 RETURN 🌈

it hands you back true if an unshadow event should be triggered, otherwise false. tiny bool, very main character energy 👑✨

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🎀 SEE ALSO 🎀

• Kernel file ./arch/s390/kvm/gmap/gmap.h, enum gmap_flags(9), pte_needs_unshadow(9), and gmap_is_shadow_valid(9) 🦋

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shoutout to the source/version line ./arch/s390/kvm/gmap and the date October 2026 — that's the footer vibe, bestie 💜💅