xen: is_hvm_{domain,vcpu} should evaluate to false when !CONFIG_HVM

Turn them into static inline functions which evaluate to false when
CONFIG_HVM is not set. ARM won't be broken because ARM guests are set
to PV type in the hypervisor.

But ARM has plan to switch to HVM guest type inside the hypervisor, so
preemptively introduce CONFIG_HVM for ARM here.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <julien.grall@arm.com>

xen/arch/arm/Kconfig

@@ -52,6 +52,9 @@ config HAS_ITS
         prompt "GICv3 ITS MSI controller support" if EXPERT = "y"
         depends on GICV3 && !NEW_VGIC
 
+config HVM
+        def_bool y
+
 config NEW_VGIC
 	bool
 	prompt "Use new VGIC implementation"

xen/include/xen/sched.h

@@ -879,8 +879,17 @@ void watchdog_domain_destroy(struct domain *d);
 
 #define is_pv_domain(d) ((d)->guest_type == guest_type_pv)
 #define is_pv_vcpu(v)   (is_pv_domain((v)->domain))
-#define is_hvm_domain(d) ((d)->guest_type == guest_type_hvm)
-#define is_hvm_vcpu(v)   (is_hvm_domain(v->domain))
+
+static inline bool is_hvm_domain(const struct domain *d)
+{
+    return IS_ENABLED(CONFIG_HVM) ? d->guest_type == guest_type_hvm : false;
+}
+
+static inline bool is_hvm_vcpu(const struct vcpu *v)
+{
+    return is_hvm_domain(v->domain);
+}
+
 #define is_pinned_vcpu(v) ((v)->domain->is_pinned || \
                            cpumask_weight((v)->cpu_hard_affinity) == 1)
 #ifdef CONFIG_HAS_PASSTHROUGH