[PATCHv2 3/7] KVM: PPC: BookE: Don't call __ffs() on an empty pending_exceptions bitmap

[Ritesh Harjani (IBM)]

kvmppc_core_check_exceptions() has the same pattern as the Book3S code:
it starts the scan of the pending exception bitmap with
__ffs(*pending) and is called from kvmppc_core_prepare_to_enter() on
every guest entry, so it routinely passes 0 to __ffs(), which is
undefined.

To be safe here, let's use find_first_bit(), which returns the bitmap
size when no bit is set.

Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@xxxxxxxxx>
---
 arch/powerpc/kvm/booke.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c
index 13ad4cf5fa71..9794ee6f7204 100644
--- a/arch/powerpc/kvm/booke.c
+++ b/arch/powerpc/kvm/booke.c
@@ -692,7 +692,7 @@ static void kvmppc_core_check_exceptions(struct kvm_vcpu *vcpu)
 	unsigned long *pending = &vcpu->arch.pending_exceptions;
 	unsigned int priority;
 
-	priority = __ffs(*pending);
+	priority = find_first_bit(pending, BITS_PER_BYTE * sizeof(*pending));
 	while (priority < BOOKE_IRQPRIO_MAX) {
 		if (kvmppc_booke_irqprio_deliver(vcpu, priority))
 			break;
-- 
2.39.5