[PATCH v4 1/5] KVM: SVM: Refactor svm_update_lbrv()

[Shivansh Dhiman <shivansh.dhiman@amd.com>]

Rewrite the enable_lbrv computation in svm_update_lbrv() as a series of
'if' statements. Rename nested_vmcb12_has_lbrv() to nested_lbrv_enabled(),
expose it, and use it instead of open-coding the nested LBRV check.

No functional change intended.

Suggested-by: Yosry Ahmed <yosry@kernel.org>
Signed-off-by: Shivansh Dhiman <shivansh.dhiman@amd.com>
Reviewed-by: Yosry Ahmed <yosry@kernel.org>
---
Changelog:
v3 -> v4:
 * Rename nested_vmcb12_has_lbrv() to nested_lbrv_enabled() (Yosry).
 * Collected Reviewed-by from Yosry.

v3:
 * New patch.
 * Refactor the enable_lbrv computation into 'if' statements (Yosry Ahmed).

---
 arch/x86/kvm/svm/nested.c |  8 ++++----
 arch/x86/kvm/svm/svm.c    | 10 +++++++---
 arch/x86/kvm/svm/svm.h    |  1 +
 3 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index c1485c3e691c..52b8d0f9b139 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -736,7 +736,7 @@ static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
 	return 0;
 }
 
-static bool nested_vmcb12_has_lbrv(struct kvm_vcpu *vcpu)
+bool nested_lbrv_enabled(struct kvm_vcpu *vcpu)
 {
 	return guest_cpu_cap_has(vcpu, X86_FEATURE_LBRV) &&
 		(to_svm(vcpu)->nested.ctl.misc_ctl2 & SVM_MISC2_ENABLE_V_LBR);
@@ -812,7 +812,7 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm)
 		vmcb_mark_dirty(vmcb02, VMCB_DR);
 	}
 
-	if (nested_vmcb12_has_lbrv(vcpu)) {
+	if (nested_lbrv_enabled(vcpu)) {
 		/*
 		 * Reserved bits of DEBUGCTL are ignored.  Be consistent with
 		 * svm_set_msr's definition of reserved bits.
@@ -1301,7 +1301,7 @@ static int nested_svm_vmexit_update_vmcb12(struct kvm_vcpu *vcpu)
 	if (guest_cpu_cap_has(vcpu, X86_FEATURE_NRIPS))
 		vmcb12->control.next_rip  = vmcb02->control.next_rip;
 
-	if (nested_vmcb12_has_lbrv(vcpu))
+	if (nested_lbrv_enabled(vcpu))
 		svm_copy_lbrs(&vmcb12->save, &vmcb02->save);
 
 	vmcb12->control.event_inj	  = 0;
@@ -1379,7 +1379,7 @@ void nested_svm_vmexit(struct vcpu_svm *svm)
 	if (!nested_exit_on_intr(svm))
 		kvm_make_request(KVM_REQ_EVENT, &svm->vcpu);
 
-	if (!nested_vmcb12_has_lbrv(vcpu)) {
+	if (!nested_lbrv_enabled(vcpu)) {
 		svm_copy_lbrs(&vmcb01->save, &vmcb02->save);
 		vmcb_mark_dirty(vmcb01, VMCB_LBR);
 	}
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index ef69a51ab27f..e9f2456982d4 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -880,9 +880,13 @@ void svm_update_lbrv(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_svm *svm = to_svm(vcpu);
 	bool current_enable_lbrv = svm->vmcb->control.misc_ctl2 & SVM_MISC2_ENABLE_V_LBR;
-	bool enable_lbrv = (svm->vmcb->save.dbgctl & DEBUGCTLMSR_LBR) ||
-			    (is_guest_mode(vcpu) && guest_cpu_cap_has(vcpu, X86_FEATURE_LBRV) &&
-			    (svm->nested.ctl.misc_ctl2 & SVM_MISC2_ENABLE_V_LBR));
+	bool enable_lbrv = false;
+
+	if (svm->vmcb->save.dbgctl & DEBUGCTLMSR_LBR)
+		enable_lbrv = true;
+
+	if (is_guest_mode(vcpu) && nested_lbrv_enabled(vcpu))
+		enable_lbrv = true;
 
 	if (enable_lbrv && !current_enable_lbrv)
 		__svm_enable_lbrv(vcpu);
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 716be21fba33..d52010e4de97 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -899,6 +899,7 @@ void nested_copy_vmcb_control_to_cache(struct vcpu_svm *svm,
 void nested_copy_vmcb_save_to_cache(struct vcpu_svm *svm,
 				    struct vmcb_save_area *save);
 void nested_sync_control_from_vmcb02(struct vcpu_svm *svm);
+bool nested_lbrv_enabled(struct kvm_vcpu *vcpu);
 void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb);
 
 
-- 
2.43.0