powerpc/64/interrupt: Fix false warning in context tracking due to idle state

Commit 17147677 ("context_tracking: Convert state to atomic_t")
added a CONTEXT_IDLE state which can be encountered by interrupts from
kernel mode in the idle thread, causing a false positive warning.

Fixes: 17147677 ("context_tracking: Convert state to atomic_t")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220926054305.2671436-2-npiggin@gmail.com

arch/powerpc/include/asm/interrupt.h

@@ -195,7 +195,8 @@ static inline void interrupt_enter_prepare(struct pt_regs *regs)
 		 * so avoid recursion.
 		 */
 		if (TRAP(regs) != INTERRUPT_PROGRAM) {
-			CT_WARN_ON(ct_state() != CONTEXT_KERNEL);
+			CT_WARN_ON(ct_state() != CONTEXT_KERNEL &&
+				   ct_state() != CONTEXT_IDLE);
 			if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG))
 				BUG_ON(is_implicit_soft_masked(regs));
 		}