libxl: x86: factor out e820_host_sanitize

This function gets the machine E820 map and sanitize it according to PV
guest configuration.

This will be used in later patch. No functional change introduced in
this patch.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Dario Faggioli <dario.faggioli@citrix.com>
Cc: Ian Campbell <ian.campbell@citrix.com>
Cc: Ian Jackson <ian.jackson@eu.citrix.com>
Cc: Elena Ufimtseva <ufimtseva@gmail.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

tools/libxl/libxl_x86.c

@@ -207,6 +207,27 @@ static int e820_sanitize(libxl_ctx *ctx, struct e820entry src[],
     return 0;
 }
 
+static int e820_host_sanitize(libxl__gc *gc,
+                              libxl_domain_build_info *b_info,
+                              struct e820entry map[],
+                              uint32_t *nr)
+{
+    int rc;
+
+    rc = xc_get_machine_memory_map(CTX->xch, map, *nr);
+    if (rc < 0) {
+        errno = rc;
+        return ERROR_FAIL;
+    }
+
+    *nr = rc;
+
+    rc = e820_sanitize(CTX, map, nr, b_info->target_memkb,
+                       (b_info->max_memkb - b_info->target_memkb) +
+                       b_info->u.pv.slack_memkb);
+    return rc;
+}
+
 static int libxl__e820_alloc(libxl__gc *gc, uint32_t domid,
         libxl_domain_config *d_config)
 {
@@ -223,15 +244,8 @@ static int libxl__e820_alloc(libxl__gc *gc, uint32_t domid,
     if (!libxl_defbool_val(b_info->u.pv.e820_host))
         return ERROR_INVAL;
 
-    rc = xc_get_machine_memory_map(ctx->xch, map, E820MAX);
-    if (rc < 0) {
-        errno = rc;
-        return ERROR_FAIL;
-    }
-    nr = rc;
-    rc = e820_sanitize(ctx, map, &nr, b_info->target_memkb,
-                       (b_info->max_memkb - b_info->target_memkb) +
-                       b_info->u.pv.slack_memkb);
+    nr = E820MAX;
+    rc = e820_host_sanitize(gc, b_info, map, &nr);
     if (rc)
         return ERROR_FAIL;