linux-kernel - [PATCH] KVM: x86: Optimize local variable in start_sw

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Message-ID: <20240814203345.2234-2-thorsten.blum@toblux.com>
Date: Wed, 14 Aug 2024 22:33:46 +0200
From: Thorsten Blum <thorsten.blum@...lux.com>
To: seanjc@...gle.com,
	pbonzini@...hat.com,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	hpa@...or.com
Cc: kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Thorsten Blum <thorsten.blum@...lux.com>
Subject: [PATCH] KVM: x86: Optimize local variable in start_sw_tscdeadline()

Change the data type of the local variable this_tsc_khz to u32 because
virtual_tsc_khz is also declared as u32.

Since do_div() casts the divisor to u32 anyway, changing the data type
of this_tsc_khz to u32 also removes the following Coccinelle/coccicheck
warning reported by do_div.cocci:

  WARNING: do_div() does a 64-by-32 division, please consider using div64_ul instead

Compile-tested only.

Signed-off-by: Thorsten Blum <thorsten.blum@...lux.com>
---
 arch/x86/kvm/lapic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index a7172ba59ad2..40ff955c1859 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1946,7 +1946,7 @@ static void start_sw_tscdeadline(struct kvm_lapic *apic)
 	u64 ns = 0;
 	ktime_t expire;
 	struct kvm_vcpu *vcpu = apic->vcpu;
-	unsigned long this_tsc_khz = vcpu->arch.virtual_tsc_khz;
+	u32 this_tsc_khz = vcpu->arch.virtual_tsc_khz;
 	unsigned long flags;
 	ktime_t now;
 
-- 
2.45.2