The following restrictions are applicable for write data bypass to control register reads:
- An MVC instruction that writes to a control register (MVC areg, creg; MVC ucst16, creg; or MVCH ucst16, creg), must not be followed by an MVC instruction (MVC creg, areg) that reads the same control register.
- An SLA instruction that writes to a control register (SLA ucst16, LSAn or SLA ucst16, LEAn) must not be followed by an MVC instruction (MVC creg, areg) that reads the same control register.
- An SLA instruction that writes to a control register (SLA ucst16, LSAn or SLA ucst16, LEAn) must not be followed by an MVCH instruction (MVCH creg, areg) that reads the same control register.