x86/kvm: Don't waste memory if kvmclock is disabled

Even if "no-kvmclock" is passed in cmdline parameter, the guest kernel
still allocates hvclock_mem which is scaled by the number of vCPUs,
let's check kvmclock enable in advance to avoid this memory waste.

Signed-off-by: Wanpeng Li <[e-mail]>
Message-Id: <[e-mail]>
Signed-off-by: Paolo Bonzini <[e-mail]>

arch/x86/kernel/kvmclock.c

···
 
 static int __init kvm_setup_vsyscall_timeinfo(void)
 {
+	if (!kvmclock)
+		return 0;
+
 	kvmclock_init_mem();
 
 #ifdef CONFIG_X86_64