From: Claudio Imbrenda <imbrenda@linux.ibm.com>
Date: Tue, 2 Jun 2026 14:23:51 +0000 (+0200)
Subject: KVM: s390: vsie: Fix rmap handling in _do_shadow_crste()
X-Git-Url: http://git.ipfire.org/gitweb/index.cgi?a=commitdiff_plain;h=6af5563e827913d3e14dbf12eefd5af4aa592739;p=thirdparty%2Fkernel%2Flinux.git

KVM: s390: vsie: Fix rmap handling in _do_shadow_crste()

Fix _do_shadow_crste() to also apply a mask on the reverse address, to
prevent spurious entries from being created, like already done in
gmap_protect_rmap().

Fixes: e38c884df921 ("KVM: s390: Switch to new gmap")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Message-ID: <20260602142356.169458-6-imbrenda@linux.ibm.com>
---

diff --git a/arch/s390/kvm/gaccess.c b/arch/s390/kvm/gaccess.c
index 4f8d5592c9a9..20e28b183c1a 100644
--- a/arch/s390/kvm/gaccess.c
+++ b/arch/s390/kvm/gaccess.c
@@ -1466,15 +1466,17 @@ static int _do_shadow_crste(struct gmap *sg, gpa_t raddr, union crste *host, uni
 			    struct guest_fault *f, bool p)
 {
 	union crste newcrste, oldcrste;
-	gfn_t gfn;
+	unsigned long mask;
+	gfn_t r_gfn;
 	int rc;
 
 	lockdep_assert_held(&sg->kvm->mmu_lock);
 	lockdep_assert_held(&sg->parent->children_lock);
 
-	gfn = f->gfn & (is_pmd(*table) ? _SEGMENT_FR_MASK : _REGION3_FR_MASK);
+	mask = is_pmd(*table) ? _SEGMENT_FR_MASK : _REGION3_FR_MASK;
+	r_gfn = gpa_to_gfn(raddr) & mask;
 	scoped_guard(spinlock, &sg->host_to_rmap_lock)
-		rc = gmap_insert_rmap(sg, gfn, gpa_to_gfn(raddr), host->h.tt);
+		rc = gmap_insert_rmap(sg, f->gfn & mask, r_gfn, host->h.tt);
 	if (rc)
 		return rc;
 
@@ -1497,8 +1499,7 @@ static int _do_shadow_crste(struct gmap *sg, gpa_t raddr, union crste *host, uni
 		return -EAGAIN;
 
 	newcrste = _crste_fc1(f->pfn, oldcrste.h.tt, 0, !p);
-	gfn = gpa_to_gfn(raddr);
-	while (!dat_crstep_xchg_atomic(table, READ_ONCE(*table), newcrste, gfn, sg->asce))
+	while (!dat_crstep_xchg_atomic(table, READ_ONCE(*table), newcrste, r_gfn, sg->asce))
 		;
 	return 0;
 }