KVM: SVM: Condition sev_enabled and sev_es_enabled on CONFIG_KVM_AMD_…

…SEV=y

Define sev_enabled and sev_es_enabled as 'false' and explicitly #ifdef
out all of sev_hardware_setup() if CONFIG_KVM_AMD_SEV=n.  This kills
three birds at once:

  - Makes sev_enabled and sev_es_enabled off by default if
    CONFIG_KVM_AMD_SEV=n.  Previously, they could be on by default if
    CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=y, regardless of KVM SEV
    support.

  - Hides the sev and sev_es modules params when CONFIG_KVM_AMD_SEV=n.

  - Resolves a false positive -Wnonnull in __sev_recycle_asids() that is
    currently masked by the equivalent IS_ENABLED(CONFIG_KVM_AMD_SEV)
    check in svm_sev_enabled(), which will be dropped in a future patch.

Reviewed by: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210422021125.3417167-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/svm/sev.c

@@ -44,13 +44,18 @@
 #define MISC_CG_RES_SEV_ES MISC_CG_RES_TYPES
 #endif
 
+#ifdef CONFIG_KVM_AMD_SEV
 /* enable/disable SEV support */
 static bool sev_enabled = IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT);
 module_param_named(sev, sev_enabled, bool, 0444);
 
 /* enable/disable SEV-ES support */
 static bool sev_es_enabled = IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT);
 module_param_named(sev_es, sev_es_enabled, bool, 0444);
+#else
+#define sev_enabled false
+#define sev_es_enabled false
+#endif /* CONFIG_KVM_AMD_SEV */
 
 static u8 sev_enc_bit;
 static int sev_flush_asids(void);
@@ -1817,11 +1822,12 @@ 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;
 
-	if (!IS_ENABLED(CONFIG_KVM_AMD_SEV) || !sev_enabled || !npt_enabled)
+	if (!sev_enabled || !npt_enabled)
 		goto out;
 
 	/* Does the CPU support SEV? */
@@ -1885,6 +1891,7 @@ void __init sev_hardware_setup(void)
 out:
 	sev_enabled = sev_supported;
 	sev_es_enabled = sev_es_supported;
+#endif
 }
 
 void sev_hardware_teardown(void)