[PATCH v5 19/31] KVM: s390: gmap: Move prefix handling to kvm/s390
From: Steffen Eiden
Date: Fri Jul 31 2026 - 09:16:32 EST
Move code handling prefix page tracking from kvm/gmap to kvm/s390. This
enables other KVM implementations to use gmap without implementing
prefix handling. The prefix tracking is turned on if
KVM_S390_GUEST_HAS_PREFIX is defined.
No functional changes.
Signed-off-by: Steffen Eiden <seiden@xxxxxxxxxxxxx>
---
arch/s390/include/asm/kvm_host_s390.h | 2 ++
arch/s390/kvm/gmap/dat.c | 48 ---------------------------
arch/s390/kvm/gmap/dat.h | 1 -
arch/s390/kvm/gmap/gmap.c | 28 ----------------
arch/s390/kvm/gmap/gmap.h | 12 +------
arch/s390/kvm/gmap/prefix.h | 39 ++++++++++++++++++++++
arch/s390/kvm/s390/dat.c | 48 +++++++++++++++++++++++++++
arch/s390/kvm/s390/gmap.c | 29 ++++++++++++++++
8 files changed, 119 insertions(+), 88 deletions(-)
create mode 100644 arch/s390/kvm/gmap/prefix.h
diff --git a/arch/s390/include/asm/kvm_host_s390.h b/arch/s390/include/asm/kvm_host_s390.h
index 9e4d7ed53078..cfd95df60130 100644
--- a/arch/s390/include/asm/kvm_host_s390.h
+++ b/arch/s390/include/asm/kvm_host_s390.h
@@ -32,6 +32,8 @@
#define KVM_INTERNAL_MEM_SLOTS 1
+#define KVM_S390_GUEST_HAS_PREFIX
+
/*
* These seem to be used for allocating ->chip in the routing table, which we
* don't use. 1 is as small as we can get to reduce the needed memory. If we
diff --git a/arch/s390/kvm/gmap/dat.c b/arch/s390/kvm/gmap/dat.c
index 1ac6457de498..6252a7cd81a8 100644
--- a/arch/s390/kvm/gmap/dat.c
+++ b/arch/s390/kvm/gmap/dat.c
@@ -777,51 +777,3 @@ 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;
}
-static long dat_set_pn_crste(union crste *crstep, gfn_t gfn, gfn_t next, struct dat_walk *walk)
-{
- union crste newcrste, oldcrste;
- int *n = walk->priv;
-
- do {
- oldcrste = READ_ONCE(*crstep);
- if (!oldcrste.h.fc || oldcrste.h.i || oldcrste.h.p)
- return 0;
- if (oldcrste.s.fc1.prefix_notif)
- break;
- newcrste = oldcrste;
- newcrste.s.fc1.prefix_notif = 1;
- } while (!dat_crstep_xchg_atomic(crstep, oldcrste, newcrste, gfn, walk->asce));
- *n = 2;
- return 0;
-}
-
-static long dat_set_pn_pte(union pte *ptep, gfn_t gfn, gfn_t next, struct dat_walk *walk)
-{
- int *n = walk->priv;
- union pgste pgste;
-
- pgste = pgste_get_lock(ptep);
- if (!ptep->h.i && !ptep->h.p) {
- pgste.prefix_notif = 1;
- *n += 1;
- }
- pgste_set_unlock(ptep, pgste);
- return 0;
-}
-
-int dat_set_prefix_notif_bit(union asce asce, gfn_t gfn)
-{
- static const struct dat_walk_ops ops = {
- .pte_entry = dat_set_pn_pte,
- .pmd_entry = dat_set_pn_crste,
- .pud_entry = dat_set_pn_crste,
- };
-
- int n = 0;
-
- _dat_walk_gfn_range(gfn, gfn + 2, asce, &ops, DAT_WALK_IGN_HOLES, &n);
- if (n != 2)
- return -EAGAIN;
- return 0;
-}
-
diff --git a/arch/s390/kvm/gmap/dat.h b/arch/s390/kvm/gmap/dat.h
index e6fd201ec9b9..fb412bd07685 100644
--- a/arch/s390/kvm/gmap/dat.h
+++ b/arch/s390/kvm/gmap/dat.h
@@ -538,7 +538,6 @@ void dat_set_ptval(struct page_table *table, struct ptval_param param, unsigned
int dat_set_slot(struct kvm_s390_mmu_cache *mc, union asce asce, gfn_t start, gfn_t end,
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_perform_essa(union asce asce, gfn_t gfn, int orc, union essa_state *state, bool *dirty);
diff --git a/arch/s390/kvm/gmap/gmap.c b/arch/s390/kvm/gmap/gmap.c
index c4ed40ea3475..07915278ee98 100644
--- a/arch/s390/kvm/gmap/gmap.c
+++ b/arch/s390/kvm/gmap/gmap.c
@@ -24,11 +24,6 @@
#include "s390.h"
#include "faultin.h"
-static inline bool kvm_s390_is_in_sie(struct kvm_vcpu *vcpu)
-{
- return vcpu->arch.sie_block->prog0c & PROG_IN_SIE;
-}
-
static int gmap_limit_to_type(gfn_t limit)
{
if (!limit)
@@ -256,29 +251,6 @@ int s390_replace_asce(struct gmap *gmap)
return 0;
}
-bool _gmap_unmap_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end, bool hint)
-{
- struct kvm *kvm = gmap->kvm;
- struct kvm_vcpu *vcpu;
- gfn_t prefix_gfn;
- unsigned long i;
-
- if (is_shadow(gmap))
- return false;
- kvm_for_each_vcpu(i, vcpu, kvm) {
- /* Match against both prefix pages */
- prefix_gfn = gpa_to_gfn(kvm_s390_get_prefix(vcpu));
- if (prefix_gfn < end && gfn <= prefix_gfn + 1) {
- if (hint && kvm_s390_is_in_sie(vcpu))
- return false;
- VCPU_EVENT(vcpu, 2, "gmap notifier for %llx-%llx",
- gfn_to_gpa(gfn), gfn_to_gpa(end));
- kvm_s390_sync_request(KVM_REQ_REFRESH_GUEST_PREFIX, vcpu);
- }
- }
- return true;
-}
-
struct clear_young_pte_priv {
struct gmap *gmap;
bool young;
diff --git a/arch/s390/kvm/gmap/gmap.h b/arch/s390/kvm/gmap/gmap.h
index c9cab8f60f62..28ab585db7e1 100644
--- a/arch/s390/kvm/gmap/gmap.h
+++ b/arch/s390/kvm/gmap/gmap.h
@@ -11,6 +11,7 @@
#define ARCH_KVM_GMAP_GMAP_H
#include "dat.h"
+#include "prefix.h"
/**
* enum gmap_flags - Flags of a gmap.
@@ -83,7 +84,6 @@ struct gmap_cache {
for (pos = (head); n = pos ? pos->next : NULL, pos; pos = n)
int s390_replace_asce(struct gmap *gmap);
-bool _gmap_unmap_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end, bool hint);
bool gmap_age_gfn(struct gmap *gmap, gfn_t start, gfn_t end);
bool gmap_unmap_gfn_range(struct gmap *gmap, struct kvm_memory_slot *slot, gfn_t start, gfn_t end);
int gmap_try_fixup_minor(struct gmap *gmap, struct guest_fault *fault);
@@ -157,16 +157,6 @@ static inline void gmap_handle_vsie_unshadow_event(struct gmap *parent, gfn_t gf
_gmap_handle_vsie_unshadow_event(parent, gfn);
}
-static inline bool gmap_mkold_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end)
-{
- return _gmap_unmap_prefix(gmap, gfn, end, true);
-}
-
-static inline bool gmap_unmap_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end)
-{
- return _gmap_unmap_prefix(gmap, gfn, end, false);
-}
-
/**
* pte_needs_unshadow() -- Check if the pte operations triggers unshadowing.
* @oldpte: the previous value for the guest pte.
diff --git a/arch/s390/kvm/gmap/prefix.h b/arch/s390/kvm/gmap/prefix.h
new file mode 100644
index 000000000000..f83b6c2c4afa
--- /dev/null
+++ b/arch/s390/kvm/gmap/prefix.h
@@ -0,0 +1,39 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef ARCH_KVM_GMAP_PREFIX_H
+#define ARCH_KVM_GMAP_PREFIX_H
+
+#include "asm/dat-bits.h"
+#include <linux/types.h>
+#include <linux/kvm_types.h>
+#include <linux/kvm_host.h>
+
+struct gmap;
+union asce;
+
+#ifdef KVM_S390_GUEST_HAS_PREFIX
+bool _gmap_unmap_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end, bool hint);
+int dat_set_prefix_notif_bit(union asce asce, gfn_t gfn);
+#else
+static inline bool _gmap_unmap_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end, bool hint)
+{
+ return true;
+}
+
+static inline int dat_set_prefix_notif_bit(union asce asce, gfn_t gfn)
+{
+ return 0;
+}
+#endif /* KVM_S390_GUEST_HAS_PREFIX */
+
+static inline bool gmap_mkold_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end)
+{
+ return _gmap_unmap_prefix(gmap, gfn, end, true);
+}
+
+static inline bool gmap_unmap_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end)
+{
+ return _gmap_unmap_prefix(gmap, gfn, end, false);
+}
+
+#endif /* ARCH_KVM_GMAP_PREFIX_H */
diff --git a/arch/s390/kvm/s390/dat.c b/arch/s390/kvm/s390/dat.c
index ff2d6c1cf90e..a56b1523e6e4 100644
--- a/arch/s390/kvm/s390/dat.c
+++ b/arch/s390/kvm/s390/dat.c
@@ -504,3 +504,51 @@ int dat_set_cmma_bits(struct kvm_s390_mmu_cache *mc, union asce asce, gfn_t gfn,
}
return _dat_walk_gfn_range(gfn, gfn + count, asce, &ops, DAT_WALK_IGN_HOLES, &state);
}
+
+static long dat_set_pn_crste(union crste *crstep, gfn_t gfn, gfn_t next, struct dat_walk *walk)
+{
+ union crste newcrste, oldcrste;
+ int *n = walk->priv;
+
+ do {
+ oldcrste = READ_ONCE(*crstep);
+ if (!oldcrste.h.fc || oldcrste.h.i || oldcrste.h.p)
+ return 0;
+ if (oldcrste.s.fc1.prefix_notif)
+ break;
+ newcrste = oldcrste;
+ newcrste.s.fc1.prefix_notif = 1;
+ } while (!dat_crstep_xchg_atomic(crstep, oldcrste, newcrste, gfn, walk->asce));
+ *n = 2;
+ return 0;
+}
+
+static long dat_set_pn_pte(union pte *ptep, gfn_t gfn, gfn_t next, struct dat_walk *walk)
+{
+ int *n = walk->priv;
+ union pgste pgste;
+
+ pgste = pgste_get_lock(ptep);
+ if (!ptep->h.i && !ptep->h.p) {
+ pgste.prefix_notif = 1;
+ *n += 1;
+ }
+ pgste_set_unlock(ptep, pgste);
+ return 0;
+}
+
+int dat_set_prefix_notif_bit(union asce asce, gfn_t gfn)
+{
+ static const struct dat_walk_ops ops = {
+ .pte_entry = dat_set_pn_pte,
+ .pmd_entry = dat_set_pn_crste,
+ .pud_entry = dat_set_pn_crste,
+ };
+
+ int n = 0;
+
+ _dat_walk_gfn_range(gfn, gfn + 2, asce, &ops, DAT_WALK_IGN_HOLES, &n);
+ if (n != 2)
+ return -EAGAIN;
+ return 0;
+}
diff --git a/arch/s390/kvm/s390/gmap.c b/arch/s390/kvm/s390/gmap.c
index 83def0ed2284..b744992f0af1 100644
--- a/arch/s390/kvm/s390/gmap.c
+++ b/arch/s390/kvm/s390/gmap.c
@@ -3,6 +3,7 @@
#include <linux/kvm_host.h>
#include <asm/gmap_helpers.h>
#include <gmap.h>
+#include <prefix.h>
#include "s390.h"
static int _gmap_enable_skeys(struct gmap *gmap)
@@ -82,3 +83,31 @@ void _gmap_set_cmma_all(struct gmap *gmap, bool dirty)
} while (gfn);
}
+static inline bool kvm_s390_is_in_sie(struct kvm_vcpu *vcpu)
+{
+ return vcpu->arch.sie_block->prog0c & PROG_IN_SIE;
+}
+
+bool _gmap_unmap_prefix(struct gmap *gmap, gfn_t gfn, gfn_t end, bool hint)
+{
+ struct kvm *kvm = gmap->kvm;
+ struct kvm_vcpu *vcpu;
+ gfn_t prefix_gfn;
+ unsigned long i;
+
+ if (is_shadow(gmap))
+ return false;
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ /* Match against both prefix pages */
+ prefix_gfn = gpa_to_gfn(kvm_s390_get_prefix(vcpu));
+ if (prefix_gfn < end && gfn <= prefix_gfn + 1) {
+ if (hint && kvm_s390_is_in_sie(vcpu))
+ return false;
+ VCPU_EVENT(vcpu, 2, "gmap notifier for %llx-%llx",
+ gfn_to_gpa(gfn), gfn_to_gpa(end));
+ kvm_s390_sync_request(KVM_REQ_REFRESH_GUEST_PREFIX, vcpu);
+ }
+ }
+ return true;
+}
+
--
2.53.0