Merge remote-tracking branch 'remotes/sstabellini/tags/xen-20160905' into staging

Xen 2016/09/05

# gpg: Signature made Mon 05 Sep 2016 19:59:47 BST
# gpg:                using RSA key 0x894F8F4870E1AE90
# gpg: Good signature from "Stefano Stabellini <stefano.stabellini@eu.citrix.com>"
# Primary key fingerprint: D04E 33AB A51F 67BA 07D3  0AEA 894F 8F48 70E1 AE90

* remotes/sstabellini/tags/xen-20160905:
  xen: use native disk xenbus protocol if possible
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/block/xen_disk.c

@@ -976,14 +976,16 @@ static int blk_connect(struct XenDevice *xendev)
         blkdev->feature_persistent = !!pers;
     }
 
-    blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
-    if (blkdev->xendev.protocol) {
-        if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_32) == 0) {
-            blkdev->protocol = BLKIF_PROTOCOL_X86_32;
-        }
-        if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_64) == 0) {
-            blkdev->protocol = BLKIF_PROTOCOL_X86_64;
-        }
+    if (!blkdev->xendev.protocol) {
+        blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
+    } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_NATIVE) == 0) {
+        blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
+    } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_32) == 0) {
+        blkdev->protocol = BLKIF_PROTOCOL_X86_32;
+    } else if (strcmp(blkdev->xendev.protocol, XEN_IO_PROTO_ABI_X86_64) == 0) {
+        blkdev->protocol = BLKIF_PROTOCOL_X86_64;
+    } else {
+        blkdev->protocol = BLKIF_PROTOCOL_NATIVE;
     }
 
     blkdev->sring = xengnttab_map_grant_ref(blkdev->xendev.gnttabdev,