xen/arm: route_irq_to_guest: Check validity of the IRQ

Currently Xen only supports SPIs routing for guest, add a function
is_assignable_irq to check if we can assign a given IRQ to the guest.

Secondly, make sure the vIRQ is not the greater than the number of IRQs
configured in the vGIC and it's an SPI.

Thirdly, when the IRQ is already assigned to the domain, check the user
is not asking to use a different vIRQ than the one already bound.

Finally, desc->arch.type which contains the IRQ type (i.e level/edge) must
be correctly configured before. The misconfiguration can happen when:
    - the device has been blacklisted for the current platform
    - the IRQ has not been described in the device tree

Also, use XENLOG_G_ERR in the error message within the function as it will
be later called from a guest.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index beb746ae79615eb5242524693a8ea5fd1895cf22..4c3e38141d1544aa876fce8e28a2df9ffea6f9be 100644 (file)
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -387,6 +387,16 @@ err:
     return rc;
 }
 
+bool_t is_assignable_irq(unsigned int irq)
+{
+    /* For now, we can only route SPIs to the guest */
+    return ((irq >= NR_LOCAL_IRQS) && (irq < gic_number_lines()));
+}
+
+/*
+ * Route an IRQ to a specific guest.
+ * For now only SPIs are assignable to the guest.
+ */
 int route_irq_to_guest(struct domain *d, unsigned int virq,
                        unsigned int irq, const char * devname)
 {
@@ -396,6 +406,28 @@ int route_irq_to_guest(struct domain *d, unsigned int virq,
     unsigned long flags;
     int retval = 0;
 
+    if ( virq >= vgic_num_irqs(d) )
+    {
+        printk(XENLOG_G_ERR
+               "the vIRQ number %u is too high for domain %u (max = %u)\n",
+               irq, d->domain_id, vgic_num_irqs(d));
+        return -EINVAL;
+    }
+
+    /* Only routing to virtual SPIs is supported */
+    if ( virq < NR_LOCAL_IRQS )
+    {
+        printk(XENLOG_G_ERR "IRQ can only be routed to an SPI");
+        return -EINVAL;
+    }
+
+    if ( !is_assignable_irq(irq) )
+    {
+        printk(XENLOG_G_ERR "the IRQ%u is not routable\n", irq);
+        return -EINVAL;
+    }
+    desc = irq_to_desc(irq);
+
     action = xmalloc(struct irqaction);
     if ( !action )
         return -ENOMEM;
@@ -416,8 +448,18 @@ int route_irq_to_guest(struct domain *d, unsigned int virq,
 
     spin_lock_irqsave(&desc->lock, flags);
 
-    /* If the IRQ is already used by someone
-     *  - If it's the same domain -> Xen doesn't need to update the IRQ desc
+    if ( desc->arch.type == DT_IRQ_TYPE_INVALID )
+    {
+        printk(XENLOG_G_ERR "IRQ %u has not been configured\n", irq);
+        retval = -EIO;
+        goto out;
+    }
+
+    /*
+     * If the IRQ is already used by someone
+     *  - If it's the same domain -> Xen doesn't need to update the IRQ desc.
+     *  For safety check if we are not trying to assign the IRQ to a
+     *  different vIRQ.
      *  - Otherwise -> For now, don't allow the IRQ to be shared between
      *  Xen and domains.
      */
@@ -426,13 +468,22 @@ int route_irq_to_guest(struct domain *d, unsigned int virq,
         struct domain *ad = irq_get_domain(desc);
 
         if ( test_bit(_IRQ_GUEST, &desc->status) && d == ad )
+        {
+            if ( irq_get_guest_info(desc)->virq != virq )
+            {
+                printk(XENLOG_G_ERR
+                       "d%u: IRQ %u is already assigned to vIRQ %u\n",
+                       d->domain_id, irq, irq_get_guest_info(desc)->virq);
+                retval = -EBUSY;
+            }
             goto out;
+        }
 
         if ( test_bit(_IRQ_GUEST, &desc->status) )
-            printk(XENLOG_ERR "ERROR: IRQ %u is already used by domain %u\n",
+            printk(XENLOG_G_ERR "IRQ %u is already used by domain %u\n",
                    irq, ad->domain_id);
         else
-            printk(XENLOG_ERR "ERROR: IRQ %u is already used by Xen\n", irq);
+            printk(XENLOG_G_ERR "IRQ %u is already used by Xen\n", irq);
         retval = -EBUSY;
         goto out;
     }

diff --git a/xen/include/asm-arm/irq.h b/xen/include/asm-arm/irq.h
index f00eb111a36651f6dd2461e86dee40fef331f2fa..71b39e707966bf7f8069d633f87a7d1998077ef0 100644 (file)
--- a/xen/include/asm-arm/irq.h
+++ b/xen/include/asm-arm/irq.h
@@ -37,6 +37,8 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, int is_fiq);
 
 #define domain_pirq_to_irq(d, pirq) (pirq)
 
+bool_t is_assignable_irq(unsigned int irq);
+
 void init_IRQ(void);
 void init_secondary_IRQ(void);