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KVM: s390: Fix _gmap_crstep_xchg_atomic()

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The previous incorrect behaviour cleared the vsie_notif bit without
returning false, which allowed shadow crstes to be installed without
the vsie_notif bit.

Return false and do not perform the operation if an unshadow event has
been triggered, but still attempt to clear the vsie_notif bit from the
existing crste.

This will prevent the installation of shadow crstes without vsie_notif
bit and will also prevent the caller from looping forever if it was
not checking for the sg->invalidated flag.

Fixes: b827ef02f4 ("KVM: s390: Remove non-atomic dat_crstep_xchg()")
Fixes: a2c17f9270 ("KVM: s390: New gmap code")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260602142356.169458-3-imbrenda@linux.ibm.com>
This commit is contained in:
Claudio Imbrenda
2026-06-02 16:23:48 +02:00
parent 29e8751c1d
commit d1adc098ce
1 changed files with 3 additions and 0 deletions
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3
arch/s390/kvm/gmap.h
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@@ -273,11 +273,14 @@ static inline bool __must_check _gmap_crstep_xchg_atomic(struct gmap *gmap, unio
gmap_unmap_prefix(gmap, gfn, gfn + align);
}
if (crste_leaf(oldcrste) && crste_needs_unshadow(oldcrste, newcrste)) {
newcrste = oldcrste;
newcrste.s.fc1.vsie_notif = 0;
if (needs_lock)
gmap_handle_vsie_unshadow_event(gmap, gfn);
else
_gmap_handle_vsie_unshadow_event(gmap, gfn);
dat_crstep_xchg_atomic(crstep, oldcrste, newcrste, gfn, gmap->asce);
return false;
}
if (!oldcrste.s.fc1.d && newcrste.s.fc1.d && !newcrste.s.fc1.s)
SetPageDirty(phys_to_page(crste_origin_large(newcrste)));