Revert "core: Only park CPUs in cell_set_loadable if really necessary"

This reverts commit ed4c781.

We do need the parking in order to resume the target cell's CPUs. Since
that commit, duplicate "cell shutdown" caused the target cell to spin
in suspension.

Leave a comment in the code as well to avoid future confusion.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

hypervisor/control.c

@@ -598,14 +598,18 @@ static int cell_set_loadable(struct per_cpu *cpu_data, unsigned long id)
 	if (err)
 		return err;
 
-	if (cell->loadable)
-		goto out_resume;
-
+	/*
+	 * Unconditionally park so that the target cell's CPUs don't stay in
+	 * suspension mode.
+	 */
 	for_each_cpu(cpu, cell->cpu_set) {
 		per_cpu(cpu)->failed = false;
 		arch_park_cpu(cpu);
 	}
 
+	if (cell->loadable)
+		goto out_resume;
+
 	cell->comm_page.comm_region.cell_state = JAILHOUSE_CELL_SHUT_DOWN;
 	cell->loadable = true;