Xen: Use the ioreq-server API when available

The ioreq-server API added to Xen 4.5 offers better security than
the existing Xen/QEMU interface because the shared pages that are
used to pass emulation request/results back and forth are removed
from the guest's memory space before any requests are serviced.
This prevents the guest from mapping these pages (they are in a
well known location) and attempting to attack QEMU by synthesizing
its own request structures. Hence, this patch modifies configure
to detect whether the API is available, and adds the necessary
code to use the API if it is.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

1 files changed, 29 insertions, 0 deletions

diff --git a/configure b/configure
index 7539645..5ea1014 100755
--- a/configure
+++ b/configure
@@ -1877,6 +1877,32 @@ int main(void) {
   xc_gnttab_open(NULL, 0);
   xc_domain_add_to_physmap(0, 0, XENMAPSPACE_gmfn, 0, 0);
   xc_hvm_inject_msi(xc, 0, 0xf0000000, 0x00000000);
+  xc_hvm_create_ioreq_server(xc, 0, 0, NULL);
+  return 0;
+}
+EOF
+      compile_prog "" "$xen_libs"
+    then
+    xen_ctrl_version=450
+    xen=yes
+
+  elif
+      cat > $TMPC <<EOF &&
+#include <xenctrl.h>
+#include <xenstore.h>
+#include <stdint.h>
+#include <xen/hvm/hvm_info_table.h>
+#if !defined(HVM_MAX_VCPUS)
+# error HVM_MAX_VCPUS not defined
+#endif
+int main(void) {
+  xc_interface *xc;
+  xs_daemon_open();
+  xc = xc_interface_open(0, 0, 0);
+  xc_hvm_set_mem_type(0, 0, HVMMEM_ram_ro, 0, 0);
+  xc_gnttab_open(NULL, 0);
+  xc_domain_add_to_physmap(0, 0, XENMAPSPACE_gmfn, 0, 0);
+  xc_hvm_inject_msi(xc, 0, 0xf0000000, 0x00000000);
   return 0;
 }
 EOF
@@ -4283,6 +4309,9 @@ if test -n "$sparc_cpu"; then
     echo "Target Sparc Arch $sparc_cpu"
 fi
 echo "xen support       $xen"
+if test "$xen" = "yes" ; then
+  echo "xen ctrl version  $xen_ctrl_version"
+fi
 echo "brlapi support    $brlapi"
 echo "bluez  support    $bluez"
 echo "Documentation     $docs"