linux-kernel - [PATCH] KVM: nVMX: allow compiling with W=1

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Date:   Thu, 27 Feb 2020 21:49:52 -0500
From:   "Valdis Klētnieks" <valdis.kletnieks@...edu>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>
cc:     x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] KVM: nVMX: allow compiling with W=1

Compile error with CONFIG_KVM_INTEL=y and W=1:

  CC      arch/x86/kvm/vmx/vmx.o
arch/x86/kvm/vmx/vmx.c:68:32: error: 'vmx_cpu_id' defined but not used [-Werror=unused-const-variable=]
   68 | static const struct x86_cpu_id vmx_cpu_id[] = {
      |                                ^~~~~~~~~~
cc1: all warnings being treated as errors

When building with =y, the MODULE_DEVICE_TABLE macro doesn't generate a
reference to the structure (or any code at all).  This makes W=1 compiles
unhappy.

Wrap both in a #ifdef to avoid the issue.

Signed-off-by: Valdis Kletnieks <valdis.kletnieks@...edu>

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 40a1467d1655..5c2fc2177b0d 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -65,11 +65,13 @@
 MODULE_AUTHOR("Qumranet");
 MODULE_LICENSE("GPL");
 
+#ifdef MODULE
 static const struct x86_cpu_id vmx_cpu_id[] = {
 	X86_FEATURE_MATCH(X86_FEATURE_VMX),
 	{}
 };
 MODULE_DEVICE_TABLE(x86cpu, vmx_cpu_id);
+#endif
 
 bool __read_mostly enable_vpid = 1;
 module_param_named(vpid, enable_vpid, bool, 0444);