linux-kernel - [PATCH 5.10 001/148] KVM/VMX: Use TEST %REG,%REG instead of CMP $0,%REG in vmenter.S

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Date:   Sat, 23 Jul 2022 11:53:33 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Uros Bizjak <ubizjak@...il.com>,
        Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH 5.10 001/148] KVM/VMX: Use TEST %REG,%REG instead of CMP $0,%REG in vmenter.S

From: Uros Bizjak <ubizjak@...il.com>

commit 6c44221b05236cc65d76cb5dc2463f738edff39d upstream.

Saves one byte in __vmx_vcpu_run for the same functionality.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Uros Bizjak <ubizjak@...il.com>
Message-Id: <20201029140457.126965-1-ubizjak@...il.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/vmx/vmenter.S |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -132,7 +132,7 @@ SYM_FUNC_START(__vmx_vcpu_run)
 	mov (%_ASM_SP), %_ASM_AX
 
 	/* Check if vmlaunch or vmresume is needed */
-	cmpb $0, %bl
+	testb %bl, %bl
 
 	/* Load guest registers.  Don't clobber flags. */
 	mov VCPU_RCX(%_ASM_AX), %_ASM_CX