There is a special dance the OS has to perform in order to do it. In short, the OS calls EWB instruction, which makes CPU read the page from EPC, encrypt it, an

There is a special dance the OS has to perform in order to do it. In short, the OS calls EWB instruction, which makes CPU read the page from EPC, encrypt it, and write it to normal memory. To load it back, OS executes the ELDB instruction, which decrypts it and writes to EPC. There is slightly more to it due to version array, which is used to prevent replay attacks, but in general, paging in and out is completely fine in SGX.