linux-kernel - [PATCH for-6.8 4/5] KVM: LoongArch: Streamline control flow of kvm_check

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Date: Wed, 14 Feb 2024 18:15:56 +0800
From: WANG Xuerui <kernel@...0n.name>
To: Paolo Bonzini <pbonzini@...hat.com>,
	Huacai Chen <chenhuacai@...nel.org>
Cc: Tianrui Zhao <zhaotianrui@...ngson.cn>,
	Bibo Mao <maobibo@...ngson.cn>,
	kvm@...r.kernel.org,
	loongarch@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	WANG Xuerui <git@...0n.name>
Subject: [PATCH for-6.8 4/5] KVM: LoongArch: Streamline control flow of kvm_check_cpucfg

From: WANG Xuerui <git@...0n.name>

All the checks currently done in kvm_check_cpucfg can be realized with
early returns, so just do that to avoid extra cognitive burden related
to the return value handling.

The default branch is unreachable because of the earlier validation by
_kvm_get_cpucfg_mask, so mark it as such too to make things clearer.

Signed-off-by: WANG Xuerui <git@...0n.name>
---
 arch/loongarch/kvm/vcpu.c | 23 +++++++++++------------
 1 file changed, 11 insertions(+), 12 deletions(-)

diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index e973500611b4..9e108ffaba30 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -339,24 +339,23 @@ static int kvm_check_cpucfg(int id, u64 val)
 		/* CPUCFG2 features checking */
 		if (val & ~mask)
 			/* The unsupported features should not be set */
-			ret = -EINVAL;
-		else if (!(val & CPUCFG2_LLFTP))
+			return -EINVAL;
+		if (!(val & CPUCFG2_LLFTP))
 			/* The LLFTP must be set, as guest must has a constant timer */
-			ret = -EINVAL;
-		else if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))
+			return -EINVAL;
+		if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))
 			/* Single and double float point must both be set when enable FP */
-			ret = -EINVAL;
-		else if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))
+			return -EINVAL;
+		if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))
 			/* FP should be set when enable LSX */
-			ret = -EINVAL;
-		else if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))
+			return -EINVAL;
+		if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))
 			/* LSX, FP should be set when enable LASX, and FP has been checked before. */
-			ret = -EINVAL;
-		break;
+			return -EINVAL;
+		return 0;
 	default:
-		break;
+		unreachable();
 	}
-	return ret;
 }
 
 static int kvm_get_one_reg(struct kvm_vcpu *vcpu,
-- 
2.43.0