It's a far/long jump, which sets loads the code segment descriptor using the selector specified.
jmp to a code segment selector which is the same as the existing
CS value reloads the descriptor.
See the Intel Software Developer's Manual Section 126.96.36.199 "Far Control Transfer Instructions" and the description of the JMP instruction:
In protected mode, the JMP instruction also allows jumps to a call gate, a task gate, and a task-state segment.
The JMP and CALL instructions (see Section 7.3.8, “Control Transfer Instructions”) both accept a far pointer as a destination to transfer program control to a segment other than the segment currently being pointed to by the CS register.
Far Jumps in Protected Mode. When the processor is operating in protected mode, the JMP instruction can be used
to perform the following three types of far jumps:
• A far jump to a conforming or non-conforming code segment.
• A far jump through a call gate.
• A task switch.