diff options
| -rw-r--r-- | hw/s390x/virtio-ccw.c | 18 |
1 files changed, 10 insertions, 8 deletions
diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c index c1f4bb1d33..3c988a000b 100644 --- a/hw/s390x/virtio-ccw.c +++ b/hw/s390x/virtio-ccw.c @@ -786,9 +786,10 @@ static inline VirtioCcwDevice *to_virtio_ccw_dev_fast(DeviceState *d) static uint8_t virtio_set_ind_atomic(SubchDev *sch, uint64_t ind_loc, uint8_t to_be_set) { - uint8_t ind_old, ind_new; + uint8_t expected, actual; hwaddr len = 1; - uint8_t *ind_addr; + /* avoid multiple fetches */ + uint8_t volatile *ind_addr; ind_addr = cpu_physical_memory_map(ind_loc, &len, true); if (!ind_addr) { @@ -796,14 +797,15 @@ static uint8_t virtio_set_ind_atomic(SubchDev *sch, uint64_t ind_loc, __func__, sch->cssid, sch->ssid, sch->schid); return -1; } + actual = *ind_addr; do { - ind_old = *ind_addr; - ind_new = ind_old | to_be_set; - } while (atomic_cmpxchg(ind_addr, ind_old, ind_new) != ind_old); - trace_virtio_ccw_set_ind(ind_loc, ind_old, ind_new); - cpu_physical_memory_unmap(ind_addr, len, 1, len); + expected = actual; + actual = atomic_cmpxchg(ind_addr, expected, expected | to_be_set); + } while (actual != expected); + trace_virtio_ccw_set_ind(ind_loc, actual, actual | to_be_set); + cpu_physical_memory_unmap((void *)ind_addr, len, 1, len); - return ind_old; + return actual; } static void virtio_ccw_notify(DeviceState *d, uint16_t vector) |