KVM: VMX: use cmpxchg64

This fixes a compilation failure on 32-bit systems.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -2238,7 +2238,7 @@ static void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
 			new.ndst = (dest << 8) & 0xFF00;
 
 		new.sn = 0;
-	} while (cmpxchg(&pi_desc->control, old.control,
+	} while (cmpxchg64(&pi_desc->control, old.control,
 			   new.control) != old.control);
 }
 
@@ -11730,7 +11730,7 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)
 
 		/* set 'NV' to 'notification vector' */
 		new.nv = POSTED_INTR_VECTOR;
-	} while (cmpxchg(&pi_desc->control, old.control,
+	} while (cmpxchg64(&pi_desc->control, old.control,
 			   new.control) != old.control);
 
 	if (!WARN_ON_ONCE(vcpu->pre_pcpu == -1)) {
@@ -11800,7 +11800,7 @@ static int pi_pre_block(struct kvm_vcpu *vcpu)
 
 		/* set 'NV' to 'wakeup vector' */
 		new.nv = POSTED_INTR_WAKEUP_VECTOR;
-	} while (cmpxchg(&pi_desc->control, old.control,
+	} while (cmpxchg64(&pi_desc->control, old.control,
 			   new.control) != old.control);
 
 	/* We should not block the vCPU if an interrupt is posted for it.  */