linux-kernel - [PATCH v2 1/2] KVM: x86: Remove unnecessory assignment to uret->data

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Message-Id: <20220311102643.807507-2-zhenzhong.duan@intel.com>
Date:   Fri, 11 Mar 2022 18:26:42 +0800
From:   Zhenzhong Duan <zhenzhong.duan@...el.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     pbonzini@...hat.com, seanjc@...gle.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org
Subject: [PATCH v2 1/2] KVM: x86: Remove unnecessory assignment to uret->data

While update_transition_efer() doesn't unconditionally set uret->data,
which on the surface makes this look suspect, but it's safe because
uret->data is consumed if and only if uret->load_into_hardware is
true, and it's (a) set to false if uret->data isn't updated and
(b) uret->data is guaranteed to be updated before it's set to true.

Drop the local "msr" and use "vmx" directly instead of redoing to_vmx().

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...el.com>
---
 arch/x86/kvm/vmx/vmx.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index b730d799c26e..cadb3769031c 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2871,21 +2871,17 @@ static void enter_rmode(struct kvm_vcpu *vcpu)
 int vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
 	struct vcpu_vmx *vmx = to_vmx(vcpu);
-	struct vmx_uret_msr *msr = vmx_find_uret_msr(vmx, MSR_EFER);
 
 	/* Nothing to do if hardware doesn't support EFER. */
-	if (!msr)
+	if (!vmx_find_uret_msr(vmx, MSR_EFER))
 		return 0;
 
 	vcpu->arch.efer = efer;
-	if (efer & EFER_LMA) {
-		vm_entry_controls_setbit(to_vmx(vcpu), VM_ENTRY_IA32E_MODE);
-		msr->data = efer;
-	} else {
-		vm_entry_controls_clearbit(to_vmx(vcpu), VM_ENTRY_IA32E_MODE);
+	if (efer & EFER_LMA)
+		vm_entry_controls_setbit(vmx, VM_ENTRY_IA32E_MODE);
+	else
+		vm_entry_controls_clearbit(vmx, VM_ENTRY_IA32E_MODE);
 
-		msr->data = efer & ~EFER_LME;
-	}
 	vmx_setup_uret_msrs(vmx);
 	return 0;
 }
-- 
2.25.1