linux-kernel - [PATCH v1 04/11] KVM: x86: use u16 for logical VCPU mask in lapic

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Message-Id: <20160630205429.16480-5-rkrcmar@redhat.com>
Date:	Thu, 30 Jun 2016 22:54:22 +0200
From:	Radim Krčmář <rkrcmar@...hat.com>
To:	linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	"Lan, Tianyu" <tianyu.lan@...el.com>,
	Igor Mammedov <imammedo@...hat.com>,
	Jan Kiszka <jan.kiszka@....de>, Peter Xu <peterx@...hat.com>
Subject: [PATCH v1 04/11] KVM: x86: use u16 for logical VCPU mask in lapic

for_all_bits() never were type safe, so we don't lose safety when
casting u16 * to unsigned long * and u16 is the size we want to avoid
mishaps when sending the pointer to functions that operate only on 16
bits.

Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
---
 arch/x86/kvm/lapic.c | 18 ++++++++----------
 1 file changed, 8 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index eed5af46e619..4296bb7353ff 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -694,7 +694,7 @@ static void kvm_apic_disabled_lapic_found(struct kvm *kvm)
  */
 static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, struct kvm_lapic *src,
 		struct kvm_lapic_irq *irq, struct kvm_apic_map *map,
-		struct kvm_lapic ***dst, unsigned long *bitmap)
+		struct kvm_lapic ***dst, u16 *bitmap)
 {
 	int i, lowest;
 	bool x2apic_ipi;
@@ -723,9 +723,7 @@ static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, struct kvm_lapic
 		return true;
 	}
 
-	*bitmap = 0;
-	if (!kvm_apic_map_get_logical_dest(map, irq->dest_id, dst,
-				(u16 *)bitmap))
+	if (!kvm_apic_map_get_logical_dest(map, irq->dest_id, dst, bitmap))
 		return false;
 
 	if (!kvm_lowest_prio_delivery(irq))
@@ -733,7 +731,7 @@ static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, struct kvm_lapic
 
 	if (!kvm_vector_hashing_enabled()) {
 		lowest = -1;
-		for_each_set_bit(i, bitmap, 16) {
+		for_each_set_bit(i, (unsigned long *)bitmap, 16) {
 			if (!(*dst)[i])
 				continue;
 			if (lowest < 0)
@@ -747,7 +745,7 @@ static inline bool kvm_apic_map_get_dest_lapic(struct kvm *kvm, struct kvm_lapic
 			return true;
 
 		lowest = kvm_vector_to_index(irq->vector, hweight16(*bitmap),
-				bitmap, 16);
+				(unsigned long *)bitmap, 16);
 
 		if (!(*dst)[lowest]) {
 			kvm_apic_disabled_lapic_found(kvm);
@@ -765,7 +763,7 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 		struct kvm_lapic_irq *irq, int *r, struct dest_map *dest_map)
 {
 	struct kvm_apic_map *map;
-	unsigned long bitmap;
+	u16 bitmap;
 	struct kvm_lapic **dst = NULL;
 	int i;
 	bool ret;
@@ -782,7 +780,7 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
 
 	ret = kvm_apic_map_get_dest_lapic(kvm, src, irq, map, &dst, &bitmap);
 	if (ret)
-		for_each_set_bit(i, &bitmap, 16) {
+		for_each_set_bit(i, (unsigned long *)&bitmap, 16) {
 			if (!dst[i])
 				continue;
 			if (*r < 0)
@@ -812,7 +810,7 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,
 			struct kvm_vcpu **dest_vcpu)
 {
 	struct kvm_apic_map *map;
-	unsigned long bitmap;
+	u16 bitmap;
 	struct kvm_lapic **dst = NULL;
 	bool ret = false;
 
@@ -824,7 +822,7 @@ bool kvm_intr_is_single_vcpu_fast(struct kvm *kvm, struct kvm_lapic_irq *irq,
 
 	if (kvm_apic_map_get_dest_lapic(kvm, NULL, irq, map, &dst, &bitmap) &&
 			hweight16(bitmap) == 1) {
-		unsigned long i = find_first_bit(&bitmap, 16);
+		unsigned long i = find_first_bit((unsigned long *)&bitmap, 16);
 
 		if (dst[i]) {
 			*dest_vcpu = dst[i]->vcpu;
-- 
2.9.0