[PATCH v2 1/2] restrict concept of pIRQ to x86

[Jan Beulich <jbeulich@xxxxxxxx>]

... 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.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
---
I'm not really certain about XEN_DOMCTL_irq_permission: With pIRQ-s not
used, the prior pIRQ -> IRQ translation cannot have succeeded on Arm, so
quite possibly the entire domctl is unused there? Yet then how is access
to particular device IRQs being granted/revoked?
---
v2: New.

--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -1120,7 +1120,7 @@ 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>`
--- a/xen/arch/arm/include/asm/irq.h
+++ b/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;
--- a/xen/arch/x86/Kconfig
+++ b/xen/arch/x86/Kconfig
@@ -25,6 +25,7 @@ config X86
        select HAS_PCI
        select HAS_PCI_MSI
        select HAS_PDX
+       select HAS_PIRQ
        select HAS_SCHED_GRANULARITY
        select HAS_UBSAN
        select HAS_VPCI if HVM
--- a/xen/common/Kconfig
+++ b/xen/common/Kconfig
@@ -56,6 +56,9 @@ config HAS_KEXEC
 config HAS_PDX
        bool
 
+config HAS_PIRQ
+       bool
+
 config HAS_PMAP
        bool
 
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -350,6 +350,8 @@ static int late_hwdom_init(struct domain
 #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_g
 }
 custom_param("extra_guest_irqs", parse_extra_guest_irqs);
 
+#endif /* CONFIG_HAS_PIRQ */
+
 /*
  * Release resources held by a domain.  There may or may not be live
  * references to the domain, and it may or may not be fully constructed.
@@ -653,6 +657,7 @@ struct domain *domain_create(domid_t dom
     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) )
@@ -664,6 +669,7 @@ struct domain *domain_create(domid_t dom
 
         radix_tree_init(&d->pirq_tree);
     }
+#endif
 
     if ( (err = arch_domain_create(d, config, flags)) != 0 )
         goto fail;
@@ -755,7 +761,9 @@ struct domain *domain_create(domid_t dom
     {
         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);
@@ -1151,7 +1159,9 @@ static void cf_check complete_domain_des
 
     evtchn_destroy_final(d);
 
+#ifdef CONFIG_HAS_PIRQ
     radix_tree_destroy(&d->pirq_tree, free_pirq_struct);
+#endif
 
     xfree(d->vcpu);
 
@@ -1864,6 +1874,8 @@ long do_vm_assist(unsigned int cmd, unsi
 }
 #endif
 
+#ifdef CONFIG_HAS_PIRQ
+
 struct pirq *pirq_get_info(struct domain *d, int pirq)
 {
     struct pirq *info = pirq_info(d, pirq);
@@ -1893,6 +1905,8 @@ 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;
--- a/xen/common/domctl.c
+++ b/xen/common/domctl.c
@@ -683,11 +683,13 @@ long do_domctl(XEN_GUEST_HANDLE_PARAM(xe
         unsigned int pirq = op->u.irq_permission.pirq, irq;
         int allow = op->u.irq_permission.allow_access;
 
+#ifdef CONFIG_HAS_PIRQ
         if ( pirq >= current->domain->nr_pirqs )
         {
             ret = -EINVAL;
             break;
         }
+#endif
         irq = pirq_access_permitted(current->domain, pirq);
         if ( !irq || xsm_irq_permission(XSM_HOOK, d, irq, allow) )
             ret = -EPERM;
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -555,6 +555,7 @@ static int evtchn_bind_ipi(evtchn_bind_i
     return rc;
 }
 
+#ifdef CONFIG_HAS_PIRQ
 
 static void link_pirq_port(int port, struct evtchn *chn, struct vcpu *v)
 {
@@ -580,9 +581,11 @@ static void unlink_pirq_port(struct evtc
             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];
@@ -639,6 +642,9 @@ static int evtchn_bind_pirq(evtchn_bind_
     write_unlock(&d->event_lock);
 
     return rc;
+#else /* !CONFIG_HAS_PIRQ */
+    return -EOPNOTSUPP;
+#endif
 }
 
 
@@ -671,6 +677,7 @@ int evtchn_close(struct domain *d1, int
     case ECS_UNBOUND:
         break;
 
+#ifdef CONFIG_HAS_PIRQ
     case ECS_PIRQ: {
         struct pirq *pirq = pirq_info(d1, chn1->u.pirq.irq);
 
@@ -680,14 +687,13 @@ int evtchn_close(struct domain *d1, int
                 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;
@@ -1097,6 +1103,8 @@ int evtchn_bind_vcpu(evtchn_port_t port,
     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;
@@ -1106,6 +1114,8 @@ int evtchn_bind_vcpu(evtchn_port_t port,
                           cpumask_of(v->processor));
         link_pirq_port(port, chn, v);
         break;
+#endif
+
     default:
         rc = -EINVAL;
         break;
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -438,12 +438,14 @@ 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 */