The commit 
842f4be95899 ("KVM: VMX: Add a trampoline to fix VMREAD error
handling") removed the declaration of vmread_error() causes a W=1 build
failure with KVM_WERROR=y. Fix it by adding it back.
arch/x86/kvm/vmx/vmx.c:359:17: error: no previous prototype for 'vmread_error' [-Werror=missing-prototypes]
 asmlinkage void vmread_error(unsigned long field, bool fault)
                 ^~~~~~~~~~~~
Signed-off-by: Qian Cai <cai@lca.pw>
Message-Id: <
20200402153955.1695-1-cai@lca.pw>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
 
 
 #define __ex(x) __kvm_handle_fault_on_reboot(x)
 
+asmlinkage void vmread_error(unsigned long field, bool fault);
 __attribute__((regparm(0))) void vmread_error_trampoline(unsigned long field,
                                                         bool fault);
 void vmwrite_error(unsigned long field, unsigned long value);