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KVM: s390: vsie: Fix nested guest memory shadowing

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Fix _do_shadow_pte() to use the correct pointer (guest pte instead of
nested guest) to set up the new pte.

Add a check to return -EOPNOTSUPP if the mapping for the nested guest
is writeable but the same page in the guest is only read-only.

Fixes: e38c884df9 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
This commit is contained in:
Claudio Imbrenda 2026-03-26 14:17:15 +01:00
parent 0f2b760a17
commit fd7bc612cf
1 changed files with 15 additions and 6 deletions
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21
arch/s390/kvm/gaccess.c
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@ -1436,13 +1436,19 @@ static int _do_shadow_pte(struct gmap *sg, gpa_t raddr, union pte *ptep_h, union
if (!pgste_get_trylock(ptep_h, &pgste))
return -EAGAIN;
newpte = _pte(f->pfn, f->writable, !p, 0);
newpte.s.d |= ptep->s.d;
newpte.s.sd |= ptep->s.sd;
newpte.h.p &= ptep->h.p;
pgste = _gmap_ptep_xchg(sg->parent, ptep_h, newpte, pgste, f->gfn, false);
pgste.vsie_notif = 1;
newpte = _pte(f->pfn, f->writable, !p, ptep_h->s.s);
newpte.s.d |= ptep_h->s.d;
newpte.s.sd |= ptep_h->s.sd;
newpte.h.p &= ptep_h->h.p;
if (!newpte.h.p && !f->writable) {
rc = -EOPNOTSUPP;
} else {
pgste = _gmap_ptep_xchg(sg->parent, ptep_h, newpte, pgste, f->gfn, false);
pgste.vsie_notif = 1;
}
pgste_set_unlock(ptep_h, pgste);
if (rc)
return rc;
newpte = _pte(f->pfn, 0, !p, 0);
if (!pgste_get_trylock(ptep, &pgste))
@ -1477,6 +1483,9 @@ static int _do_shadow_crste(struct gmap *sg, gpa_t raddr, union crste *host, uni
newcrste.h.p &= oldcrste.h.p;
newcrste.s.fc1.vsie_notif = 1;
newcrste.s.fc1.prefix_notif = oldcrste.s.fc1.prefix_notif;
newcrste.s.fc1.s = oldcrste.s.fc1.s;
if (!newcrste.h.p && !f->writable)
return -EOPNOTSUPP;
} while (!_gmap_crstep_xchg_atomic(sg->parent, host, oldcrste, newcrste, f->gfn, false));
newcrste = _crste_fc1(f->pfn, oldcrste.h.tt, 0, !p);