Commit fd7bc612 authored by Claudio Imbrenda's avatar Claudio Imbrenda
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KVM: s390: vsie: Fix nested guest memory shadowing 



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: e38c884d ("KVM: s390: Switch to new gmap")
Signed-off-by: default avatarClaudio Imbrenda <imbrenda@linux.ibm.com>
parent 0f2b760a

arch/s390/kvm/gaccess.c

+15 −6
Original line number Diff line number Diff line
@@ -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;

	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);