/usr/share/vim/vim80/autoload/xml/ is in vim-runtime 2:8.0.1453-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/vim/vim80/autoload/xml/html32.vim
/usr/share/vim/vim80/autoload/xml/html401f.vim
/usr/share/vim/vim80/autoload/xml/html401s.vim
/usr/share/vim/vim80/autoload/xml/html401t.vim
/usr/share/vim/vim80/autoload/xml/html40f.vim
/usr/share/vim/vim80/autoload/xml/html40s.vim
/usr/share/vim/vim80/autoload/xml/html40t.vim
/usr/share/vim/vim80/autoload/xml/xhtml10f.vim
/usr/share/vim/vim80/autoload/xml/xhtml10s.vim
/usr/share/vim/vim80/autoload/xml/xhtml10t.vim
/usr/share/vim/vim80/autoload/xml/xhtml11.vim
/usr/share/vim/vim80/autoload/xml/xsd.vim
/usr/share/vim/vim80/autoload/xml/xsl.vim