From Longman Dictionary of Contemporary Englishbe all smiles/innocence/sweetness etcbe all smiles/innocence/sweetness etcto be showing a lot of a particular quality or type of behaviour The mayor and mayoress were all smiles and kisses during the grand ceremony. → all
Examples from the Corpus
be all smiles/innocence/sweetness etc• In the resulting calm Tam and his brother resurfaced and were all smiles.• When he entered the kitchen, bringing a great gust of cold air with him, he was all smiles.• Instead, this way, they were all innocence, all planning.• Fakhru was all smiles and had his son by the throat.• But the next day Zara and Johnson were all smiles as they enjoyed a day out at a pub.• Your eyes are all innocence, but your lips are pure fire.• And the sporty victim herself was all smiles, too. 