linux-kernel - [PATCH 07/10] KVM: SVM: Use guard(mutex) to simplify SNP AP Creation error handling

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Message-ID: <20250219012705.1495231-8-seanjc@google.com>
Date: Tue, 18 Feb 2025 17:27:02 -0800
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, 
	Naveen N Rao <naveen@...nel.org>, Kim Phillips <kim.phillips@....com>, 
	Tom Lendacky <thomas.lendacky@....com>, Alexey Kardashevskiy <aik@....com>
Subject: [PATCH 07/10] KVM: SVM: Use guard(mutex) to simplify SNP AP Creation
 error handling

Use guard(mutex) in sev_snp_ap_creation() and modify the error paths to
return directly instead of jumping to a common exit point.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/sev.c | 22 ++++++----------------
 1 file changed, 6 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 7f6c8fedb235..241cf7769508 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3940,7 +3940,6 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm)
 	struct vcpu_svm *target_svm;
 	unsigned int request;
 	unsigned int apic_id;
-	int ret;
 
 	request = lower_32_bits(svm->vmcb->control.exit_info_1);
 	apic_id = upper_32_bits(svm->vmcb->control.exit_info_1);
@@ -3953,11 +3952,9 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm)
 		return -EINVAL;
 	}
 
-	ret = 0;
-
 	target_svm = to_svm(target_vcpu);
 
-	mutex_lock(&target_svm->sev_es.snp_vmsa_mutex);
+	guard(mutex)(&target_svm->sev_es.snp_vmsa_mutex);
 
 	switch (request) {
 	case SVM_VMGEXIT_AP_CREATE_ON_INIT:
@@ -3965,15 +3962,13 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm)
 		if (vcpu->arch.regs[VCPU_REGS_RAX] != sev->vmsa_features) {
 			vcpu_unimpl(vcpu, "vmgexit: mismatched AP sev_features [%#lx] != [%#llx] from guest\n",
 				    vcpu->arch.regs[VCPU_REGS_RAX], sev->vmsa_features);
-			ret = -EINVAL;
-			goto out;
+			return -EINVAL;
 		}
 
 		if (!page_address_valid(vcpu, svm->vmcb->control.exit_info_2)) {
 			vcpu_unimpl(vcpu, "vmgexit: invalid AP VMSA address [%#llx] from guest\n",
 				    svm->vmcb->control.exit_info_2);
-			ret = -EINVAL;
-			goto out;
+			return -EINVAL;
 		}
 
 		/*
@@ -3987,8 +3982,7 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm)
 			vcpu_unimpl(vcpu,
 				    "vmgexit: AP VMSA address [%llx] from guest is unsafe as it is 2M aligned\n",
 				    svm->vmcb->control.exit_info_2);
-			ret = -EINVAL;
-			goto out;
+			return -EINVAL;
 		}
 
 		target_svm->sev_es.snp_vmsa_gpa = svm->vmcb->control.exit_info_2;
@@ -3999,8 +3993,7 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm)
 	default:
 		vcpu_unimpl(vcpu, "vmgexit: invalid AP creation request [%#x] from guest\n",
 			    request);
-		ret = -EINVAL;
-		goto out;
+		return -EINVAL;
 	}
 
 	target_svm->sev_es.snp_ap_waiting_for_reset = true;
@@ -4014,10 +4007,7 @@ static int sev_snp_ap_creation(struct vcpu_svm *svm)
 		kvm_vcpu_kick(target_vcpu);
 	}
 
-out:
-	mutex_unlock(&target_svm->sev_es.snp_vmsa_mutex);
-
-	return ret;
+	return 0;
 }
 
 static int snp_handle_guest_req(struct vcpu_svm *svm, gpa_t req_gpa, gpa_t resp_gpa)
-- 
2.48.1.601.g30ceb7b040-goog