restrict concept of pIRQ to x86

... by way of a new arch-selectable Kconfig control.

Note that some smaller pieces of code are left without #ifdef, to keep
things better readable. Hence items like ECS_PIRQ, nr_static_irqs, or
domain_pirq_to_irq() remain uniformly.

As to XEN_DOMCTL_irq_permission - this, despite having a uniformly
available wrapper in libxc, is unused on Arm: libxl bypasses those
calls, and the Python and OCamL bindings have no users at all.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>

docs/misc/xen-command-line.pandoc

@@ -1165,7 +1165,7 @@ introduced with the Nehalem architecture.
       intended as an emergency option for people who first chose fast, then
       change their minds to secure, and wish not to reboot.**
 
-### extra_guest_irqs
+### extra_guest_irqs (x86)
 > `= [<domU number>][,<dom0 number>]`
 
 > Default: `32,<variable>`

xen/arch/arm/include/asm/irq.h

@@ -52,7 +52,6 @@ struct arch_irq_desc {
 
 extern const unsigned int nr_irqs;
 #define nr_static_irqs NR_IRQS
-#define arch_hwdom_irqs(domid) NR_IRQS
 
 struct irq_desc;
 struct irqaction;

xen/arch/x86/Kconfig

@@ -26,6 +26,7 @@ config X86
 	select HAS_PASSTHROUGH
 	select HAS_PCI
 	select HAS_PCI_MSI
+	select HAS_PIRQ
 	select HAS_SCHED_GRANULARITY
 	select HAS_UBSAN
 	select HAS_VPCI if HVM

xen/common/Kconfig

@@ -71,6 +71,9 @@ config HAS_IOPORTS
 config HAS_KEXEC
 	bool
 
+config HAS_PIRQ
+	bool
+
 config HAS_PMAP
 	bool
 

xen/common/domain.c

@@ -350,6 +350,8 @@ static int late_hwdom_init(struct domain *d)
 #endif
 }
 
+#ifdef CONFIG_HAS_PIRQ
+
 static unsigned int __read_mostly extra_hwdom_irqs;
 static unsigned int __read_mostly extra_domU_irqs = 32;
 
@@ -364,6 +366,8 @@ static int __init cf_check parse_extra_guest_irqs(const char *s)
 }
 custom_param("extra_guest_irqs", parse_extra_guest_irqs);
 
+#endif /* CONFIG_HAS_PIRQ */
+
 static int __init cf_check parse_dom0_param(const char *s)
 {
     const char *ss;
@@ -683,6 +687,7 @@ struct domain *domain_create(domid_t domid,
     if ( is_system_domain(d) && !is_idle_domain(d) )
         return d;
 
+#ifdef CONFIG_HAS_PIRQ
     if ( !is_idle_domain(d) )
     {
         if ( !is_hardware_domain(d) )
@@ -694,6 +699,7 @@ struct domain *domain_create(domid_t domid,
 
         radix_tree_init(&d->pirq_tree);
     }
+#endif
 
     if ( (err = arch_domain_create(d, config, flags)) != 0 )
         goto fail;
@@ -793,7 +799,9 @@ struct domain *domain_create(domid_t domid,
     {
         evtchn_destroy(d);
         evtchn_destroy_final(d);
+#ifdef CONFIG_HAS_PIRQ
         radix_tree_destroy(&d->pirq_tree, free_pirq_struct);
+#endif
     }
     if ( init_status & INIT_watchdog )
         watchdog_domain_destroy(d);
@@ -1192,7 +1200,9 @@ static void cf_check complete_domain_destroy(struct rcu_head *head)
 
     evtchn_destroy_final(d);
 
+#ifdef CONFIG_HAS_PIRQ
     radix_tree_destroy(&d->pirq_tree, free_pirq_struct);
+#endif
 
     xfree(d->vcpu);
 
@@ -2058,6 +2068,8 @@ long do_vm_assist(unsigned int cmd, unsigned int type)
 }
 #endif
 
+#ifdef CONFIG_HAS_PIRQ
+
 struct pirq *pirq_get_info(struct domain *d, int pirq)
 {
     struct pirq *info = pirq_info(d, pirq);
@@ -2087,6 +2099,8 @@ void cf_check free_pirq_struct(void *ptr)
     call_rcu(&pirq->rcu_head, _free_pirq_struct);
 }
 
+#endif /* CONFIG_HAS_PIRQ */
+
 struct migrate_info {
     long (*func)(void *data);
     void *data;

xen/common/domctl.c

@@ -648,6 +648,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
         }
         break;
 
+#ifdef CONFIG_HAS_PIRQ
     case XEN_DOMCTL_irq_permission:
     {
         unsigned int pirq = op->u.irq_permission.pirq, irq;
@@ -667,6 +668,7 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xen_domctl_t) u_domctl)
             ret = irq_deny_access(d, irq);
         break;
     }
+#endif
 
     case XEN_DOMCTL_iomem_permission:
     {

xen/common/event_channel.c

@@ -566,6 +566,7 @@ static int evtchn_bind_ipi(evtchn_bind_ipi_t *bind)
     return rc;
 }
 
+#ifdef CONFIG_HAS_PIRQ
 
 static void link_pirq_port(int port, struct evtchn *chn, struct vcpu *v)
 {
@@ -591,9 +592,11 @@ static void unlink_pirq_port(struct evtchn *chn, struct vcpu *v)
             chn->u.pirq.prev_port;
 }
 
+#endif /* CONFIG_HAS_PIRQ */
 
 static int evtchn_bind_pirq(evtchn_bind_pirq_t *bind)
 {
+#ifdef CONFIG_HAS_PIRQ
     struct evtchn *chn;
     struct domain *d = current->domain;
     struct vcpu   *v = d->vcpu[0];
@@ -663,6 +666,9 @@ static int evtchn_bind_pirq(evtchn_bind_pirq_t *bind)
     write_unlock(&d->event_lock);
 
     return rc;
+#else /* !CONFIG_HAS_PIRQ */
+    return -EOPNOTSUPP;
+#endif
 }
 
 
@@ -695,6 +701,7 @@ int evtchn_close(struct domain *d1, int port1, bool guest)
     case ECS_UNBOUND:
         break;
 
+#ifdef CONFIG_HAS_PIRQ
     case ECS_PIRQ: {
         struct pirq *pirq = pirq_info(d1, chn1->u.pirq.irq);
 
@@ -704,14 +711,13 @@ int evtchn_close(struct domain *d1, int port1, bool guest)
                 pirq_guest_unbind(d1, pirq);
             pirq->evtchn = 0;
             pirq_cleanup_check(pirq, d1);
-#ifdef CONFIG_X86
             if ( is_hvm_domain(d1) && domain_pirq_to_irq(d1, pirq->pirq) > 0 )
                 unmap_domain_pirq_emuirq(d1, pirq->pirq);
-#endif
         }
         unlink_pirq_port(chn1, d1->vcpu[chn1->notify_vcpu_id]);
         break;
     }
+#endif
 
     case ECS_VIRQ: {
         struct vcpu *v;
@@ -1121,6 +1127,8 @@ int evtchn_bind_vcpu(evtchn_port_t port, unsigned int vcpu_id)
     case ECS_INTERDOMAIN:
         chn->notify_vcpu_id = v->vcpu_id;
         break;
+
+#ifdef CONFIG_HAS_PIRQ
     case ECS_PIRQ:
         if ( chn->notify_vcpu_id == v->vcpu_id )
             break;
@@ -1130,6 +1138,8 @@ int evtchn_bind_vcpu(evtchn_port_t port, unsigned int vcpu_id)
                           cpumask_of(v->processor));
         link_pirq_port(port, chn, v);
         break;
+#endif
+
     default:
         rc = -EINVAL;
         break;

xen/include/xen/sched.h

@@ -439,12 +439,14 @@ struct domain
 
     struct grant_table *grant_table;
 
+#ifdef CONFIG_HAS_PIRQ
     /*
      * Interrupt to event-channel mappings and other per-guest-pirq data.
      * Protected by the domain's event-channel spinlock.
      */
     struct radix_tree_root pirq_tree;
     unsigned int     nr_pirqs;
+#endif
 
     unsigned int     options;         /* copy of createdomain flags */