Comment 6 for bug 1852168

@Gorka Eguileor
The qemu patch is：
https://github.com/qemu/qemu/commit/78368575a63df3ef95653024fa21a91d441b0c8d

static ssize_t block_crypto_init_func(QCryptoBlock *block,
                                      size_t headerlen,
                                      Error **errp,
                                      void *opaque)
{
    struct BlockCryptoCreateData *data = opaque;
    int ret;

    /* User provided size should reflect amount of space made ★★★★★
     * available to the guest, so we must take account of that ★★★★★
     * which will be used by the crypto header ★★★★★
     */
    data->size += headerlen;