[PATCH 4/4] KVM: SVM: Compile sev.c if and only if CONFIG_KVM_AMD_SEV=y

[Sean Christopherson]

Stop compiling sev.c when CONFIG_KVM_AMD_SEV=n, as the number of #ifdefs
in sev.c is getting ridiculous, and having #ifdefs inside of SEV helpers
is quite confusing.

To minimize #ifdefs in code flows, #idef away only the kvm_x86_ops hooks
and the #VMGEXIT handler, and instead rely on dead code elimination to
take care of functions that are guarded with sev_guest(), sev_es_guest(),
or an IS_ENABLED(CONFIG_KVM_AMD_SEV).

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/x86/kvm/Makefile  |  7 ++++---
 arch/x86/kvm/svm/sev.c | 23 -----------------------
 arch/x86/kvm/svm/svm.c |  6 ++++--
 arch/x86/kvm/svm/svm.h | 23 ++++++++++++++++-------
 4 files changed, 24 insertions(+), 35 deletions(-)

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 475b5fa917a6..744a1ea3ee5c 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -25,9 +25,10 @@ kvm-intel-y		+= vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o \
 kvm-intel-$(CONFIG_X86_SGX_KVM)	+= vmx/sgx.o
 kvm-intel-$(CONFIG_KVM_HYPERV)	+= vmx/hyperv.o vmx/hyperv_evmcs.o
 
-kvm-amd-y		+= svm/svm.o svm/vmenter.o svm/pmu.o svm/nested.o svm/avic.o \
-			   svm/sev.o
-kvm-amd-$(CONFIG_KVM_HYPERV) += svm/hyperv.o
+kvm-amd-y		+= svm/svm.o svm/vmenter.o svm/pmu.o svm/nested.o svm/avic.o
+
+kvm-amd-$(CONFIG_KVM_AMD_SEV)	+= svm/sev.o
+kvm-amd-$(CONFIG_KVM_HYPERV)	+= svm/hyperv.o
 
 ifdef CONFIG_HYPERV
 kvm-y			+= kvm_onhyperv.o
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index a0f270f976aa..e1b356e1f6e8 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -32,22 +32,6 @@
 #include "cpuid.h"
 #include "trace.h"
 
-#ifndef CONFIG_KVM_AMD_SEV
-/*
- * When this config is not defined, SEV feature is not supported and APIs in
- * this file are not used but this file still gets compiled into the KVM AMD
- * module.
- *
- * We will not have MISC_CG_RES_SEV and MISC_CG_RES_SEV_ES entries in the enum
- * misc_res_type {} defined in linux/misc_cgroup.h.
- *
- * Below macros allow compilation to succeed.
- */
-#define MISC_CG_RES_SEV MISC_CG_RES_TYPES
-#define MISC_CG_RES_SEV_ES MISC_CG_RES_TYPES
-#endif
-
-#ifdef CONFIG_KVM_AMD_SEV
 /* enable/disable SEV support */
 static bool sev_enabled = true;
 module_param_named(sev, sev_enabled, bool, 0444);
@@ -59,11 +43,6 @@ module_param_named(sev_es, sev_es_enabled, bool, 0444);
 /* enable/disable SEV-ES DebugSwap support */
 static bool sev_es_debug_swap_enabled = true;
 module_param_named(debug_swap, sev_es_debug_swap_enabled, bool, 0444);
-#else
-#define sev_enabled false
-#define sev_es_enabled false
-#define sev_es_debug_swap_enabled false
-#endif /* CONFIG_KVM_AMD_SEV */
 
 static u8 sev_enc_bit;
 static DECLARE_RWSEM(sev_deactivate_lock);
@@ -2183,7 +2162,6 @@ void __init sev_set_cpu_caps(void)
 
 void __init sev_hardware_setup(void)
 {
-#ifdef CONFIG_KVM_AMD_SEV
 	unsigned int eax, ebx, ecx, edx, sev_asid_count, sev_es_asid_count;
 	bool sev_es_supported = false;
 	bool sev_supported = false;
@@ -2283,7 +2261,6 @@ void __init sev_hardware_setup(void)
 	if (!sev_es_enabled || !cpu_feature_enabled(X86_FEATURE_DEBUG_SWAP) ||
 	    !cpu_feature_enabled(X86_FEATURE_NO_NESTED_DATA_BP))
 		sev_es_debug_swap_enabled = false;
-#endif
 }
 
 void sev_hardware_unsetup(void)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index e036a0852161..13e4151bd297 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -3310,7 +3310,9 @@ static int (*const svm_exit_handlers[])(struct kvm_vcpu *vcpu) = {
 	[SVM_EXIT_RSM]                          = rsm_interception,
 	[SVM_EXIT_AVIC_INCOMPLETE_IPI]		= avic_incomplete_ipi_interception,
 	[SVM_EXIT_AVIC_UNACCELERATED_ACCESS]	= avic_unaccelerated_access_interception,
+#ifdef CONFIG_KVM_AMD_SEV
 	[SVM_EXIT_VMGEXIT]			= sev_handle_vmgexit,
+#endif
 };
 
 static void dump_vmcb(struct kvm_vcpu *vcpu)
@@ -5019,7 +5021,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 	.leave_smm = svm_leave_smm,
 	.enable_smi_window = svm_enable_smi_window,
 #endif
-
+#ifdef CONFIG_KVM_AMD_SEV
 	.mem_enc_ioctl = sev_mem_enc_ioctl,
 	.mem_enc_register_region = sev_mem_enc_register_region,
 	.mem_enc_unregister_region = sev_mem_enc_unregister_region,
@@ -5027,7 +5029,7 @@ static struct kvm_x86_ops svm_x86_ops __initdata = {
 
 	.vm_copy_enc_context_from = sev_vm_copy_enc_context_from,
 	.vm_move_enc_context_from = sev_vm_move_enc_context_from,
-
+#endif
 	.check_emulate_instruction = svm_check_emulate_instruction,
 
 	.apic_init_signal_blocked = svm_apic_init_signal_blocked,
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 8ef95139cd24..80211ac02577 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -663,14 +663,12 @@ void avic_refresh_virtual_apic_mode(struct kvm_vcpu *vcpu);
 
 
 /* sev.c */
-
+#ifdef CONFIG_KVM_AMD_SEV
 #define GHCB_VERSION_MAX	1ULL
 #define GHCB_VERSION_MIN	1ULL
 
-
 extern unsigned int max_sev_asid;
 
-void sev_vm_destroy(struct kvm *kvm);
 int sev_mem_enc_ioctl(struct kvm *kvm, void __user *argp);
 int sev_mem_enc_register_region(struct kvm *kvm,
 				struct kvm_enc_region *range);
@@ -680,20 +678,31 @@ int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd);
 int sev_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd);
 void sev_guest_memory_reclaimed(struct kvm *kvm);
 
-void pre_sev_run(struct vcpu_svm *svm, int cpu);
+int sev_handle_vmgexit(struct kvm_vcpu *vcpu);
+#else
+#define max_sev_asid 0
+#endif
+
+/*
+ * To minimize #ifdefs, declare functions that are called directly, i.e. aren't
+ * reached via kvm_x86_ops or something other function table.  Don't provide
+ * stubs as all calls should be dropped by dead code elimination before linking.
+ */
 void __init sev_set_cpu_caps(void);
 void __init sev_hardware_setup(void);
 void sev_hardware_unsetup(void);
 int sev_cpu_init(struct svm_cpu_data *sd);
+
 void sev_init_vmcb(struct vcpu_svm *svm);
-void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm);
-void sev_free_vcpu(struct kvm_vcpu *vcpu);
-int sev_handle_vmgexit(struct kvm_vcpu *vcpu);
+void pre_sev_run(struct vcpu_svm *svm, int cpu);
 int sev_es_string_io(struct vcpu_svm *svm, int size, unsigned int port, int in);
 void sev_es_vcpu_reset(struct vcpu_svm *svm);
 void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector);
 void sev_es_prepare_switch_to_guest(struct sev_es_save_area *hostsa);
 void sev_es_unmap_ghcb(struct vcpu_svm *svm);
+void sev_vcpu_after_set_cpuid(struct vcpu_svm *svm);
+void sev_vm_destroy(struct kvm *kvm);
+void sev_free_vcpu(struct kvm_vcpu *vcpu);
 
 /* vmenter.S */
 
-- 
2.44.0.rc0.258.g7320e95886-goog


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