linux-kernel - [PATCH v3 06/13] KVM: SVM: Condition sev_enabled and sev_es_enabled on CONFIG_KVM_AMD

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Date:   Fri, 22 Jan 2021 12:21:37 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Borislav Petkov <bp@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH v3 06/13] 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@....com>
Reviewed-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/svm/sev.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index ef2ae734b6bc..2b8ebe2f1caf 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -27,6 +27,7 @@
 
 #define __ex(x) __kvm_handle_fault_on_reboot(x)
 
+#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);
@@ -34,6 +35,10 @@ 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);
@@ -1253,11 +1258,12 @@ void sev_vm_destroy(struct kvm *kvm)
 
 void __init sev_hardware_setup(void)
 {
+#ifdef CONFIG_KVM_AMD_SEV
 	unsigned int eax, ebx, ecx, edx;
 	bool sev_es_supported = false;
 	bool sev_supported = false;
 
-	if (!IS_ENABLED(CONFIG_KVM_AMD_SEV) || !sev_enabled)
+	if (!sev_enabled)
 		goto out;
 
 	/* Does the CPU support SEV? */
@@ -1312,6 +1318,7 @@ void __init sev_hardware_setup(void)
 out:
 	sev_enabled = sev_supported;
 	sev_es_enabled = sev_es_supported;
+#endif
 }
 
 void sev_hardware_teardown(void)
-- 
2.30.0.280.ga3ce27912f-goog