Merge remote-tracking branch 'remotes/aperard/tags/pull-xen-20190319' into staging

Xen queue

Fix a bug on FreeBSD when doing a migration.

# gpg: Signature made Tue 19 Mar 2019 15:40:55 GMT
# gpg:                using RSA key F80C006308E22CFD8A92E7980CF5572FD7FB55AF
# gpg:                issuer "anthony.perard@citrix.com"
# gpg: Good signature from "Anthony PERARD <anthony.perard@gmail.com>" [marginal]
# gpg:                 aka "Anthony PERARD <anthony.perard@citrix.com>" [marginal]
# gpg: WARNING: This key is not certified with sufficiently trusted signatures!
# gpg:          It is not certain that the signature belongs to the owner.
# Primary key fingerprint: 5379 2F71 024C 600F 778A  7161 D8D5 7199 DF83 42C8
#      Subkey fingerprint: F80C 0063 08E2 2CFD 8A92  E798 0CF5 572F D7FB 55AF

* remotes/aperard/tags/pull-xen-20190319:
  xen-mapcache: use MAP_FIXED flag so the mmap address hint is always honored
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>

hw/i386/xen/xen-mapcache.c

@@ -184,9 +184,14 @@ static void xen_remap_bucket(MapCacheEntry *entry,
         pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
     }
 
+    /*
+     * If the caller has requested the mapping at a specific address use
+     * MAP_FIXED to make sure it's honored.
+     */
     if (!dummy) {
         vaddr_base = xenforeignmemory_map2(xen_fmem, xen_domid, vaddr,
-                                           PROT_READ | PROT_WRITE, 0,
+                                           PROT_READ | PROT_WRITE,
+                                           vaddr ? MAP_FIXED : 0,
                                            nb_pfn, pfns, err);
         if (vaddr_base == NULL) {
             perror("xenforeignmemory_map2");
@@ -198,7 +203,8 @@ static void xen_remap_bucket(MapCacheEntry *entry,
          * mapping immediately due to certain circumstances (i.e. on resume now)
          */
         vaddr_base = mmap(vaddr, size, PROT_READ | PROT_WRITE,
-                          MAP_ANON | MAP_SHARED, -1, 0);
+                          MAP_ANON | MAP_SHARED | (vaddr ? MAP_FIXED : 0),
+                          -1, 0);
         if (vaddr_base == MAP_FAILED) {
             perror("mmap");
             exit(-1);