linux-kernel - [PATCH v1 1/1] KVM: s390: Don't cast parameter in bit operations

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Date:   Wed, 23 Feb 2022 18:44:20 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Christian Borntraeger <borntraeger@...ux.ibm.com>,
        kvm@...r.kernel.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Subject: [PATCH v1 1/1] KVM: s390: Don't cast parameter in bit operations

While in this particular case it would not be a (critical) issue,
the pattern itself is bad and error prone in case somebody blindly
copies to their code.

Don't cast parameter to unsigned long pointer in the bit operations.
Instead copy to a local variable on stack of a proper type and use.

Fixes: d77e64141e32 ("KVM: s390: implement GISA IPM related primitives")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 arch/s390/include/asm/kvm_host.h | 5 ++++-
 arch/s390/kvm/interrupt.c        | 6 +++---
 2 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a22c9266ea05..f1c4a1b9b360 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -867,7 +867,10 @@ struct kvm_s390_gisa {
 			u8  reserved03[11];
 			u32 airq_count;
 		} g1;
-		struct {
+		struct { /* as a 256-bit bitmap */
+			DECLARE_BITMAP(b, 256);
+		} bitmap;
+		struct { /* as a set of 64-bit words */
 			u64 word[4];
 		} u64;
 	};
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index db933c252dbc..04e055cbd080 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -304,7 +304,7 @@ static inline int gisa_in_alert_list(struct kvm_s390_gisa *gisa)
 
 static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
 {
-	set_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
+	set_bit_inv(IPM_BIT_OFFSET + gisc, gisa->bitmap.b);
 }
 
 static inline u8 gisa_get_ipm(struct kvm_s390_gisa *gisa)
@@ -314,12 +314,12 @@ static inline u8 gisa_get_ipm(struct kvm_s390_gisa *gisa)
 
 static inline void gisa_clear_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
 {
-	clear_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
+	clear_bit_inv(IPM_BIT_OFFSET + gisc, gisa->bitmap.b);
 }
 
 static inline int gisa_tac_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
 {
-	return test_and_clear_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
+	return test_and_clear_bit_inv(IPM_BIT_OFFSET + gisc, gisa->bitmap.b);
 }
 
 static inline unsigned long pending_irqs_no_gisa(struct kvm_vcpu *vcpu)
-- 
2.34.1