linux-kernel - [PATCH RESEND] x86/l1tf: Fix build error seen if CONFIG_KVM

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Date:   Wed, 15 Aug 2018 08:38:33 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Ingo Molnar <mingo@...hat.com>, "H . Peter Anvin" <hpa@...or.com>,
        x86@...nel.org, Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Meelis Roos <mroos@...ux.ee>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH RESEND] x86/l1tf: Fix build error seen if CONFIG_KVM_INTEL is disabled

allmodconfig+CONFIG_INTEL_KVM=n results in the following build error.

ERROR: "l1tf_vmx_mitigation" [arch/x86/kvm/kvm.ko] undefined!

Fixes: 5b76a3cff011 ("KVM: VMX: Tell the nested hypervisor to skip L1D flush on vmentry")
Reported-by: Meelis Roos <mroos@...ux.ee>
Cc: Meelis Roos <mroos@...ux.ee>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Guenter Roeck <linux@...ck-us.net>
---
Sorry for the early resend; widening the audience.

This problem affects Chrome OS builds, and I'll need to apply either
this or a similar patch.
Since I would like to avoid applying a patch just to revert it later, any
feedback if this is the correct patch or even the right approach would be
most appreciated.

Thanks,
Guenter

 arch/x86/kernel/cpu/bugs.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 27830880e7a7..cb4a16292aa7 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -664,10 +664,9 @@ void x86_spec_ctrl_setup_ap(void)
 enum l1tf_mitigations l1tf_mitigation __ro_after_init = L1TF_MITIGATION_FLUSH;
 #if IS_ENABLED(CONFIG_KVM_INTEL)
 EXPORT_SYMBOL_GPL(l1tf_mitigation);
-
+#endif
 enum vmx_l1d_flush_state l1tf_vmx_mitigation = VMENTER_L1D_FLUSH_AUTO;
 EXPORT_SYMBOL_GPL(l1tf_vmx_mitigation);
-#endif
 
 static void __init l1tf_select_mitigation(void)
 {
-- 
2.7.4