[PATCH -next] x86/kvm: Fix build with CONFIG_SMP disabled

[Wang ShaoBo]

When CONFIG_SMP is disabled, build failed like this:

arch/x86/kernel/kvm.c: In function ‘kvm_alloc_cpumask’:
arch/x86/kernel/kvm.c:823:35: error: ‘kvm_send_ipi_mask_allbutself’
 undeclared (first use in this function); did you mean ‘apic_send_IPI_allbutself’?
  apic->send_IPI_mask_allbutself = kvm_send_ipi_mask_allbutself;
                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
                                   apic_send_IPI_allbutself
arch/x86/kernel/kvm.c:823:35: note: each undeclared identifier
 is reported only once for each function it appears in

It is because the declaration of kvm_send_ipi_mask_allbutself() is guarded
by CONFIG_SMP. kvm_send_ipi_mask_allbutself() do not need do anything at
this time.

Signed-off-by: Wang ShaoBo <bobo.shaobowang@xxxxxxxxxx>
---
 arch/x86/kernel/kvm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index a44398d2bc44..47d65864e29c 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -611,6 +611,13 @@ static int kvm_cpu_down_prepare(unsigned int cpu)
 	local_irq_enable();
 	return 0;
 }
+
+#else /* !CONFIG_SMP */
+
+static void kvm_send_ipi_mask_allbutself(const struct cpumask *mask, int vector)
+{
+}
+
 #endif
 
 static void kvm_flush_tlb_others(const struct cpumask *cpumask,
-- 
2.25.1