libxc: properly account for the page offset when copying ACPI data

Or else ACPI data is always copied at the start of the page pointed by
guest_addr_out, ignoring the page offset.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-and-Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>

tools/libxc/xc_dom_core.c

@@ -1090,8 +1090,9 @@ static int xc_dom_load_acpi(struct xc_dom_image *dom)
                   dom->acpi_modules[i].length,
                   dom->acpi_modules[i].guest_addr_out);
 
-        num_pages = (dom->acpi_modules[i].length + (XC_PAGE_SIZE - 1)) >>
-                       XC_PAGE_SHIFT;
+        num_pages = (dom->acpi_modules[i].length +
+                     (dom->acpi_modules[i].guest_addr_out & ~XC_PAGE_MASK) +
+                     (XC_PAGE_SIZE - 1)) >> XC_PAGE_SHIFT;
         extents = malloc(num_pages * sizeof(*extents));
         if ( !extents )
         {
@@ -1118,6 +1119,9 @@ static int xc_dom_load_acpi(struct xc_dom_image *dom)
             goto err;
         }
 
+        ptr = (uint8_t *)ptr +
+              (dom->acpi_modules[i].guest_addr_out & ~XC_PAGE_MASK);
+
         memcpy(ptr, dom->acpi_modules[i].data, dom->acpi_modules[i].length);
         munmap(ptr, XC_PAGE_SIZE * num_pages);