s1 = ContourPlot3D[x^2 + z^2 == 1, {x, -1, 1}, {y, 0, 1}, {z, -1, 1}]
s2 = ContourPlot3D[
y == 1 + Sqrt[1 - x^2 - z^2], {x, -1, 1}, {y, 1, 2}, {z, -1, 1}]
Show[s1, s2, PlotRange -> All]
s1 = ContourPlot3D[x^2 + z^2 == 1, {x, -1, 1}, {y, 0, 1}, {z, -1, 1}]
s2 = ContourPlot3D[
y == 1 + Sqrt[1 - x^2 - z^2], {x, -1, 1}, {y, 1, 2}, {z, -1, 1}]
Show[s1, s2, PlotRange -> All]