linux-kernel - [PATCH 3/3] KVM: SVM: Use compound literal in lieu of __maybe

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Date: Mon, 17 Jun 2024 14:04:32 -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, 
	Borislav Petkov <bp@...en8.de>
Subject: [PATCH 3/3] KVM: SVM: Use compound literal in lieu of __maybe_unused
 rdmsr() param

When reading MSR_TSC_AUX, which is effectively a 32-bit value, use a
compound literal to consume/ignore the upper 32 bits instead of a "maybe"
unused local variable.  While (ab)using a compound literal to discard an
unused output is unusual, it's perfectly legal as compound literals are
valid, modifiable l-values in C99 and beyond.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/svm.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index cf285472fea6..69c0dea5cc0d 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -678,11 +678,8 @@ static int svm_hardware_enable(void)
 	 * Since Linux does not change the value of TSC_AUX once set, prime the
 	 * TSC_AUX field now to avoid a RDMSR on every vCPU run.
 	 */
-	if (boot_cpu_has(X86_FEATURE_V_TSC_AUX)) {
-		u32 __maybe_unused msr_hi;
-
-		rdmsr(MSR_TSC_AUX, sev_es_host_save_area(sd)->tsc_aux, msr_hi);
-	}
+	if (boot_cpu_has(X86_FEATURE_V_TSC_AUX))
+		rdmsr(MSR_TSC_AUX, sev_es_host_save_area(sd)->tsc_aux, (u32){0});
 
 	return 0;
 }
-- 
2.45.2.627.g7a2c4fd464-goog