diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 747d4f9001555fd1cf26c570038cd962919899dc..2839efcfc5ffec2e0c93d8b63e432ccf976cf9cd 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -62,6 +62,11 @@ static void prefix_mapped(struct vsie_page *vsie_page)
 	atomic_andnot(PROG_REQUEST, &vsie_page->scb_s.prog20);
 }
 
+/* test if the prefix is mapped into the gmap shadow */
+static int prefix_is_mapped(struct vsie_page *vsie_page)
+{
+	return !(atomic_read(&vsie_page->scb_s.prog20) & PROG_REQUEST);
+}
 
 /* copy the updated intervention request bits into the shadow scb */
 static void update_intervention_requests(struct vsie_page *vsie_page)
@@ -152,6 +157,7 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 {
 	struct kvm_s390_sie_block *scb_o = vsie_page->scb_o;
 	struct kvm_s390_sie_block *scb_s = &vsie_page->scb_s;
+	unsigned long new_mso;
 	int rc;
 
 	/* make sure we don't have any leftovers when reusing the scb */
@@ -192,9 +198,13 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	scb_s->ictl |= ICTL_ISKE | ICTL_SSKE | ICTL_RRBE;
 	scb_s->icpua = scb_o->icpua;
 
+	new_mso = scb_o->mso & 0xfffffffffff00000UL;
+	/* if the hva of the prefix changes, we have to remap the prefix */
+	if (scb_s->mso != new_mso || scb_s->prefix != scb_o->prefix)
+		prefix_unmapped(vsie_page);
 	 /* SIE will do mso/msl validity and exception checks for us */
 	scb_s->msl = scb_o->msl & 0xfffffffffff00000UL;
-	scb_s->mso = scb_o->mso & 0xfffffffffff00000UL;
+	scb_s->mso = new_mso;
 	scb_s->prefix = scb_o->prefix;
 
 	/* We have to definetly flush the tlb if this scb never ran */
@@ -262,6 +272,9 @@ static int map_prefix(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 	u64 prefix = scb_s->prefix << GUEST_PREFIX_SHIFT;
 	int rc;
 
+	if (prefix_is_mapped(vsie_page))
+		return 0;
+
 	/* mark it as mapped so we can catch any concurrent unmappers */
 	prefix_mapped(vsie_page);
 
@@ -532,6 +545,7 @@ static void release_gmap_shadow(struct vsie_page *vsie_page)
 	if (vsie_page->gmap)
 		gmap_put(vsie_page->gmap);
 	WRITE_ONCE(vsie_page->gmap, NULL);
+	prefix_unmapped(vsie_page);
 }
 
 static int acquire_gmap_shadow(struct kvm_vcpu *vcpu,
@@ -547,6 +561,16 @@ static int acquire_gmap_shadow(struct kvm_vcpu *vcpu,
 	edat = cr0.edat && test_kvm_facility(vcpu->kvm, 8);
 	edat += edat && test_kvm_facility(vcpu->kvm, 78);
 
+	/*
+	 * ASCE or EDAT could have changed since last icpt, or the gmap
+	 * we're holding has been unshadowed. If the gmap is still valid,
+	 * we can safely reuse it.
+	 */
+	if (vsie_page->gmap && gmap_shadow_valid(vsie_page->gmap, asce, edat))
+		return 0;
+
+	/* release the old shadow - if any, and mark the prefix as unmapped */
+	release_gmap_shadow(vsie_page);
 	gmap = gmap_shadow(vcpu->arch.gmap, asce, edat);
 	if (IS_ERR(gmap))
 		return PTR_ERR(gmap);
@@ -578,7 +602,6 @@ static int vsie_run(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
 			rc = do_vsie_run(vcpu, vsie_page);
 			gmap_enable(vcpu->arch.gmap);
 		}
-		release_gmap_shadow(vsie_page);
 
 		if (rc == -EAGAIN)
 			rc = 0;
@@ -667,6 +690,7 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr)
 
 	vsie_page = page_to_virt(page);
 	memset(&vsie_page->scb_s, 0, sizeof(struct kvm_s390_sie_block));
+	release_gmap_shadow(vsie_page);
 	vsie_page->scb_s.ihcpu = 0xffffU;
 	return vsie_page;
 }
@@ -739,6 +763,7 @@ void kvm_s390_vsie_init(struct kvm *kvm)
 /* Destroy the vsie data structures. To be called when a vm is destroyed. */
 void kvm_s390_vsie_destroy(struct kvm *kvm)
 {
+	struct vsie_page *vsie_page;
 	struct page *page;
 	int i;
 
@@ -746,6 +771,8 @@ void kvm_s390_vsie_destroy(struct kvm *kvm)
 	for (i = 0; i < kvm->arch.vsie.page_count; i++) {
 		page = kvm->arch.vsie.pages[i];
 		kvm->arch.vsie.pages[i] = NULL;
+		vsie_page = page_to_virt(page);
+		release_gmap_shadow(vsie_page);
 		/* free the radix tree entry */
 		radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9);
 		__free_page(page);