x86/kvm: Don't enable IRQ when IRQ enabled in kvm_wait

Commit f4e61f0 ("x86/kvm: Fix broken irq restoration in kvm_wait")
replaced "local_irq_restore() when IRQ enabled" with "local_irq_enable()
when IRQ enabled" to suppress a warnning.

Although there is no similar debugging warnning for doing local_irq_enable()
when IRQ enabled as doing local_irq_restore() in the same IRQ situation.  But
doing local_irq_enable() when IRQ enabled is no less broken as doing
local_irq_restore() and we'd better avoid it.

Cc: Mark Rutland <[email protected]>
Cc: Peter Zijlstra (Intel) <[email protected]>
Signed-off-by: Lai Jiangshan <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>

Author: Lai Jiangshan

arch/x86/kernel/kvm.c

@@ -884,10 +884,11 @@ static void kvm_wait(u8 *ptr, u8 val)
 	} else {
 		local_irq_disable();
 
+		/* safe_halt() will enable IRQ */
 		if (READ_ONCE(*ptr) == val)
 			safe_halt();
-
-		local_irq_enable();
+		else
+			local_irq_enable();
 	}
 }