linux-kernel - [PATCH 6/6] KVM: SVM: Return the local "r" variable from svm_set

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Date:   Tue, 21 Mar 2023 18:14:40 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Nathan Chancellor <nathan@...nel.org>,
        Emanuele Giuseppe Esposito <eesposit@...hat.com>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Jim Mattson <jmattson@...gle.com>
Subject: [PATCH 6/6] KVM: SVM: Return the local "r" variable from svm_set_msr()

Rename "r" to "ret" and actually return it from svm_set_msr() to reduce
the probability of repeating the mistake of commit 723d5fb0ffe4 ("kvm:
svm: Add IA32_FLUSH_CMD guest support"), which set "r" thinking that it
would be propagated to the caller.

Alternatively, the declaration of "r" could be moved into the handling of
MSR_TSC_AUX, but that risks variable shadowing in the future.  A wrapper
for kvm_set_user_return_msr() would allow eliding a local variable, but
that feels like delaying the inevitable.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index b32edaf5a74b..57f241c5a371 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2873,7 +2873,7 @@ static int svm_set_vm_cr(struct kvm_vcpu *vcpu, u64 data)
 static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
-	int r;
+	int ret = 0;
 
 	u32 ecx = msr->index;
 	u64 data = msr->data;
@@ -2995,10 +2995,10 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 		 * guest via direct_access_msrs, and switch it via user return.
 		 */
 		preempt_disable();
-		r = kvm_set_user_return_msr(tsc_aux_uret_slot, data, -1ull);
+		ret = kvm_set_user_return_msr(tsc_aux_uret_slot, data, -1ull);
 		preempt_enable();
-		if (r)
-			return 1;
+		if (ret)
+			break;
 
 		svm->tsc_aux = data;
 		break;
@@ -3056,7 +3056,7 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr)
 	default:
 		return kvm_set_msr_common(vcpu, msr);
 	}
-	return 0;
+	return ret;
 }
 
 static int msr_interception(struct kvm_vcpu *vcpu)
-- 
2.40.0.rc2.332.ga46443480c-goog