[PATCH] KVM: SVM: Macrofy SEV=n versions of sev_xxx_guest()

[PATCH] KVM: SVM: Macrofy SEV=n versions of sev_xxx_guest()

[Sean Christopherson]

Define sev_{,es_,snp_}guest() as "false" when SEV is disabled via Kconfig,
i.e. when CONFIG_KVM_AMD_SEV=n.  Despite the helpers being __always_inline,
gcc-12 is somehow incapable of realizing that the return value is a
compile-time constant and generates sub-optimal code.

Opportunistically clump the paths together to reduce the amount of
ifdeffery.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/svm/svm.h | 17 +++++------------
 1 file changed, 5 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 43fa6a16eb19..2f5d8b105eb0 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -358,39 +358,32 @@ static __always_inline struct kvm_sev_info *to_kvm_sev_info(struct kvm *kvm)
 	return &to_kvm_svm(kvm)->sev_info;
 }
 
+#ifdef CONFIG_KVM_AMD_SEV
 static __always_inline bool sev_guest(struct kvm *kvm)
 {
-#ifdef CONFIG_KVM_AMD_SEV
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
 
 	return sev->active;
-#else
-	return false;
-#endif
 }
-
 static __always_inline bool sev_es_guest(struct kvm *kvm)
 {
-#ifdef CONFIG_KVM_AMD_SEV
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
 
 	return sev->es_active && !WARN_ON_ONCE(!sev->active);
-#else
-	return false;
-#endif
 }
 
 static __always_inline bool sev_snp_guest(struct kvm *kvm)
 {
-#ifdef CONFIG_KVM_AMD_SEV
 	struct kvm_sev_info *sev = &to_kvm_svm(kvm)->sev_info;
 
 	return (sev->vmsa_features & SVM_SEV_FEAT_SNP_ACTIVE) &&
 	       !WARN_ON_ONCE(!sev_es_guest(kvm));
+}
 #else
-	return false;
+#define sev_guest(kvm) false
+#define sev_es_guest(kvm) false
+#define sev_snp_guest(kvm) false
 #endif
-}
 
 static inline bool ghcb_gpa_is_registered(struct vcpu_svm *svm, u64 val)
 {

base-commit: 4d911c7abee56771b0219a9fbf0120d06bdc9c14
-- 
2.47.0.338.g60cca15819-goog

Re: [PATCH] KVM: SVM: Macrofy SEV=n versions of sev_xxx_guest()

[Sean Christopherson]

On Wed, 27 Nov 2024 15:46:59 -0800, Sean Christopherson wrote:
> Define sev_{,es_,snp_}guest() as "false" when SEV is disabled via Kconfig,
> i.e. when CONFIG_KVM_AMD_SEV=n.  Despite the helpers being __always_inline,
> gcc-12 is somehow incapable of realizing that the return value is a
> compile-time constant and generates sub-optimal code.
> 
> Opportunistically clump the paths together to reduce the amount of
> ifdeffery.
> 
> [...]

Applied to kvm-x86 svm, thanks!

[1/1] KVM: SVM: Macrofy SEV=n versions of sev_xxx_guest()
      https://github.com/kvm-x86/linux/commit/45d522d3ee9c

--
https://github.com/kvm-x86/linux/tree/next