[PATCH v1 1/3] KVM: s390: Silence potential warnings in _gmap_crstep_xchg_atomic()

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

While dat_crstep_xchg_atomic() is marked as __must_check, in this
particular case the return value should be ignored.

Add an explicit (void) cast to silence potential compiler warnings, and
a comment to explain why it is ok to do so.

Fixes: d1adc098ce08 ("KVM: s390: Fix _gmap_crstep_xchg_atomic()")
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
CC: stable@vger.kernel.org # 7.1
---
 arch/s390/kvm/gmap.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kvm/gmap.h b/arch/s390/kvm/gmap.h
index 5374f21aaf8d..4e6979783e16 100644
--- a/arch/s390/kvm/gmap.h
+++ b/arch/s390/kvm/gmap.h
@@ -279,7 +279,11 @@ static inline bool __must_check _gmap_crstep_xchg_atomic(struct gmap *gmap, unio
 			gmap_handle_vsie_unshadow_event(gmap, gfn);
 		else
 			_gmap_handle_vsie_unshadow_event(gmap, gfn);
-		dat_crstep_xchg_atomic(crstep, oldcrste, newcrste, gfn, gmap->asce);
+		/*
+		 * Ignore the result, it's just a best effort clearing of the
+		 * vsie_notif bit. The caller will have to try again regardless.
+		 */
+		(void)dat_crstep_xchg_atomic(crstep, oldcrste, newcrste, gfn, gmap->asce);
 		return false;
 	}
 	if (!oldcrste.s.fc1.d && newcrste.s.fc1.d && !newcrste.s.fc1.s)
-- 
2.54.0