vmv.x.s
Vector move scalar to integer register
Copies the first element of the source vector register vs2 to the destination integer register xd, sign-extending to XLEN bits if SEW < XLEN.
This is a scalar read instruction that always reads element 0 of vs2, regardless of vstart. The vstart CSR is reset to 0 after execution.
Execution
VectorState state = vector_state();
X[xd] = $signed(V[vs2][state.sew - 1:0]);
CSR[vstart].VALUE = 0;