KVM: s390: Fix gmap_link()

The slow path of the fault handler ultimately called gmap_link(), which
assumed the fault was a major fault, and blindly called dat_link().

In case of minor faults, things were not always handled properly; in
particular the prefix and vsie marker bits were ignored.

Move dat_link() into gmap.c, renaming it accordingly. Once moved, the
new _gmap_link() function will be able to correctly honour the prefix
and vsie markers.

This will cause spurious unshadows in some uncommon cases.

Fixes: 94fd9b16cc67 ("KVM: s390: KVM page table management functions: lifecycle management")
Fixes: a2c17f9270cc ("KVM: s390: New gmap code")
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>

diff --git a/arch/s390/kvm/dat.c b/arch/s390/kvm/dat.c
index 4d44c0f9ad45c597bdd7ca7357444160b3477589..7b8d70fe406ded6499098f75515c8be9df482d13 100644 (file)
--- a/arch/s390/kvm/dat.c
+++ b/arch/s390/kvm/dat.c
@@ -997,54 +997,6 @@ bool dat_test_age_gfn(union asce asce, gfn_t start, gfn_t end)
        return _dat_walk_gfn_range(start, end, asce, &test_age_ops, 0, NULL) > 0;
 }
 
-int dat_link(struct kvm_s390_mmu_cache *mc, union asce asce, int level,
-            bool uses_skeys, struct guest_fault *f)
-{
-       union crste oldval, newval;
-       union pte newpte, oldpte;
-       union pgste pgste;
-       int rc = 0;
-
-       rc = dat_entry_walk(mc, f->gfn, asce, DAT_WALK_ALLOC_CONTINUE, level, &f->crstep, &f->ptep);
-       if (rc == -EINVAL || rc == -ENOMEM)
-               return rc;
-       if (rc)
-               return -EAGAIN;
-
-       if (WARN_ON_ONCE(unlikely(get_level(f->crstep, f->ptep) > level)))
-               return -EINVAL;
-
-       if (f->ptep) {
-               pgste = pgste_get_lock(f->ptep);
-               oldpte = *f->ptep;
-               newpte = _pte(f->pfn, f->writable, f->write_attempt | oldpte.s.d, !f->page);
-               newpte.s.sd = oldpte.s.sd;
-               oldpte.s.sd = 0;
-               if (oldpte.val == _PTE_EMPTY.val || oldpte.h.pfra == f->pfn) {
-                       pgste = __dat_ptep_xchg(f->ptep, pgste, newpte, f->gfn, asce, uses_skeys);
-                       if (f->callback)
-                               f->callback(f);
-               } else {
-                       rc = -EAGAIN;
-               }
-               pgste_set_unlock(f->ptep, pgste);
-       } else {
-               oldval = READ_ONCE(*f->crstep);
-               newval = _crste_fc1(f->pfn, oldval.h.tt, f->writable,
-                                   f->write_attempt | oldval.s.fc1.d);
-               newval.s.fc1.sd = oldval.s.fc1.sd;
-               if (oldval.val != _CRSTE_EMPTY(oldval.h.tt).val &&
-                   crste_origin_large(oldval) != crste_origin_large(newval))
-                       return -EAGAIN;
-               if (!dat_crstep_xchg_atomic(f->crstep, oldval, newval, f->gfn, asce))
-                       return -EAGAIN;
-               if (f->callback)
-                       f->callback(f);
-       }
-
-       return rc;
-}
-
 static long dat_set_pn_crste(union crste *crstep, gfn_t gfn, gfn_t next, struct dat_walk *walk)
 {
        union crste newcrste, oldcrste;

diff --git a/arch/s390/kvm/dat.h b/arch/s390/kvm/dat.h
index 22dafc775335ff0e96817d8b519d76fa298c544a..efedcf96110cc7afdbcec76bf194dc5df95b6b4d 100644 (file)
--- a/arch/s390/kvm/dat.h
+++ b/arch/s390/kvm/dat.h
@@ -540,8 +540,6 @@ int dat_set_slot(struct kvm_s390_mmu_cache *mc, union asce asce, gfn_t start, gf
                 u16 type, u16 param);
 int dat_set_prefix_notif_bit(union asce asce, gfn_t gfn);
 bool dat_test_age_gfn(union asce asce, gfn_t start, gfn_t end);
-int dat_link(struct kvm_s390_mmu_cache *mc, union asce asce, int level,
-            bool uses_skeys, struct guest_fault *f);
 
 int dat_perform_essa(union asce asce, gfn_t gfn, int orc, union essa_state *state, bool *dirty);
 long dat_reset_cmma(union asce asce, gfn_t start_gfn);

diff --git a/arch/s390/kvm/gmap.c b/arch/s390/kvm/gmap.c
index 956be4c01797fc446b44bf88b95f36faa9a8a094..03e15b5e0b9a8aa940ebc68db7d750d5c6fa4d83 100644 (file)
--- a/arch/s390/kvm/gmap.c
+++ b/arch/s390/kvm/gmap.c
@@ -631,10 +631,60 @@ static inline bool gmap_1m_allowed(struct gmap *gmap, gfn_t gfn)
        return test_bit(GMAP_FLAG_ALLOW_HPAGE_1M, &gmap->flags);
 }
 
+static int _gmap_link(struct kvm_s390_mmu_cache *mc, struct gmap *gmap, int level,
+                     struct guest_fault *f)
+{
+       union crste oldval, newval;
+       union pte newpte, oldpte;
+       union pgste pgste;
+       int rc = 0;
+
+       rc = dat_entry_walk(mc, f->gfn, gmap->asce, DAT_WALK_ALLOC_CONTINUE, level,
+                           &f->crstep, &f->ptep);
+       if (rc == -ENOMEM)
+               return rc;
+       if (KVM_BUG_ON(rc == -EINVAL, gmap->kvm))
+               return rc;
+       if (rc)
+               return -EAGAIN;
+       if (KVM_BUG_ON(get_level(f->crstep, f->ptep) > level, gmap->kvm))
+               return -EINVAL;
+
+       if (f->ptep) {
+               pgste = pgste_get_lock(f->ptep);
+               oldpte = *f->ptep;
+               newpte = _pte(f->pfn, f->writable, f->write_attempt | oldpte.s.d, !f->page);
+               newpte.s.sd = oldpte.s.sd;
+               oldpte.s.sd = 0;
+               if (oldpte.val == _PTE_EMPTY.val || oldpte.h.pfra == f->pfn) {
+                       pgste = gmap_ptep_xchg(gmap, f->ptep, newpte, pgste, f->gfn);
+                       if (f->callback)
+                               f->callback(f);
+               } else {
+                       rc = -EAGAIN;
+               }
+               pgste_set_unlock(f->ptep, pgste);
+       } else {
+               do {
+                       oldval = READ_ONCE(*f->crstep);
+                       newval = _crste_fc1(f->pfn, oldval.h.tt, f->writable,
+                                           f->write_attempt | oldval.s.fc1.d);
+                       newval.s.fc1.sd = oldval.s.fc1.sd;
+                       if (oldval.val != _CRSTE_EMPTY(oldval.h.tt).val &&
+                           crste_origin_large(oldval) != crste_origin_large(newval))
+                               return -EAGAIN;
+               } while (!gmap_crstep_xchg_atomic(gmap, f->crstep, oldval, newval, f->gfn));
+               if (f->callback)
+                       f->callback(f);
+       }
+
+       return rc;
+}
+
 int gmap_link(struct kvm_s390_mmu_cache *mc, struct gmap *gmap, struct guest_fault *f)
 {
        unsigned int order;
-       int rc, level;
+       int level;
 
        lockdep_assert_held(&gmap->kvm->mmu_lock);
 
@@ -646,9 +696,7 @@ int gmap_link(struct kvm_s390_mmu_cache *mc, struct gmap *gmap, struct guest_fau
                else if (order >= get_order(_SEGMENT_SIZE) && gmap_1m_allowed(gmap, f->gfn))
                        level = TABLE_TYPE_SEGMENT;
        }
-       rc = dat_link(mc, gmap->asce, level, uses_skeys(gmap), f);
-       KVM_BUG_ON(rc == -EINVAL, gmap->kvm);
-       return rc;
+       return _gmap_link(mc, gmap, level, f);
 }
 
 static int gmap_ucas_map_one(struct kvm_s390_mmu_cache *mc, struct gmap *gmap,