crypto: add support for nettle's native XTS impl

Nettle 3.5.0 will add support for the XTS mode. Use this because long
term we wish to delete QEMU's XTS impl to avoid carrying private crypto
algorithm impls.

Unfortunately this degrades nettle performance from 612 MB/s to 568 MB/s
as nettle's XTS impl isn't so well optimized yet.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/configure b/configure
index d1e9e457ce..452c2dfe4e 100755
--- a/configure
+++ b/configure
@@ -472,6 +472,7 @@ gtk_gl="no"
 tls_priority="NORMAL"
 gnutls=""
 nettle=""
+nettle_xts="no"
 gcrypt=""
 gcrypt_hmac="no"
 gcrypt_xts="no"
@@ -2871,6 +2872,19 @@ if test "$nettle" != "no"; then
             pass="yes"
         fi
     fi
+    if test "$pass" = "yes"
+    then
+        cat > $TMPC << EOF
+#include <nettle/xts.h>
+int main(void) {
+  return 0;
+}
+EOF
+        if compile_prog "$nettle_cflags" "$nettle_libs" ; then
+            nettle_xts=yes
+            qemu_private_xts=no
+        fi
+    fi
     if test "$pass" = "no" && test "$nettle" = "yes"; then
         feature_not_found "nettle" "Install nettle devel >= 2.7.1"
     else
@@ -6346,6 +6360,10 @@ then
    echo "  XTS             $gcrypt_xts"
 fi
 echo "nettle            $nettle $(echo_version $nettle $nettle_version)"
+if test "$nettle" = "yes"
+then
+   echo "  XTS             $nettle_xts"
+fi
 echo "libtasn1          $tasn1"
 echo "PAM               $auth_pam"
 echo "iconv support     $iconv"