From: Paolo Bonzini <pbonzini@redhat.com>
Date: Fri, 3 Mar 2023 13:36:32 +0000 (+0100)
Subject: physmem: add missing memory barrier
X-Git-Tag: v8.0.0-rc0~21^2~2
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=33828ca11da08436e1b32f3e79dabce3061a0427;p=thirdparty%2Fqemu.git

physmem: add missing memory barrier

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index 47143edb4f6..a6efd8e8dd1 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -2927,6 +2927,8 @@ void cpu_register_map_client(QEMUBH *bh)
     qemu_mutex_lock(&map_client_list_lock);
     client->bh = bh;
     QLIST_INSERT_HEAD(&map_client_list, client, link);
+    /* Write map_client_list before reading in_use.  */
+    smp_mb();
     if (!qatomic_read(&bounce.in_use)) {
         cpu_notify_map_clients_locked();
     }
@@ -3116,6 +3118,7 @@ void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
     qemu_vfree(bounce.buffer);
     bounce.buffer = NULL;
     memory_region_unref(bounce.mr);
+    /* Clear in_use before reading map_client_list.  */
     qatomic_mb_set(&bounce.in_use, false);
     cpu_notify_map_clients();
 }