error_page 500 501 502 503 504 505 = @hhvm_index_error;

location @hhvm_index_error {
root /home/work/webroot/;
set $phpvm zend;
include fastcgi_params;
fastcgi_param SCRIPT_FILENAME /home/work/webroot/$fastcgi_script_name;
fastcgi_pass 127.0.0.1:9000;
}

另外，最好用supervisor 监控下，进程死了，拉起来。当然如果需要监控的地方不多的话，shell监控也挺好的