[PATCH 08/12] KVM: x86/mmu: Use IS_ENABLED() to avoid RETPOLINE for TDP page faults

From: Sean Christopherson
Date: Fri Apr 22 2022 - 23:49:07 EST


Use IS_ENABLED() instead of an #ifdef to activate the anti-RETPOLINE fast
path for TDP page faults. The generated code is identical, and the #ifdef
makes it dangerously difficult to extend the logic (guess who forgot to
add an "else" inside the #ifdef and ran through the page fault handler
twice).

No functional or binary change intented.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu_internal.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index c0c85cbfa159..9caa747ee033 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -248,10 +248,10 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
.req_level = PG_LEVEL_4K,
.goal_level = PG_LEVEL_4K,
};
-#ifdef CONFIG_RETPOLINE
- if (fault.is_tdp)
+
+ if (IS_ENABLED(CONFIG_RETPOLINE) && fault.is_tdp)
return kvm_tdp_page_fault(vcpu, &fault);
-#endif
+
return vcpu->arch.mmu->page_fault(vcpu, &fault);
}

--
2.36.0.rc2.479.g8af0fa9b8e-goog