[Xen-devel] [RFC 04/19] xen/arm: route_irq_to_guest: Check validity of the IRQ

[Julien Grall <julien.grall@xxxxxxxxxx>]

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

Secondly, make sure the vIRQ (which is currently the same as the pIRQ) is not
the greater that the number of IRQs handle to the vGIC.

Finally, desc->arch.type which contains the IRQ type (i.e level/edge) must
be correctly configured before. The IRQ type won't be configure when:
    - the device has been blacklist for the current platform
    - the IRQ has not been describe in the device tree

I think we can safely assume that a user won't never ask to route
as such IRQ to the guest.

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@xxxxxxxxxx>
---
 xen/arch/arm/irq.c        |   32 +++++++++++++++++++++++++++++---
 xen/include/asm-arm/gic.h |    2 ++
 xen/include/asm-arm/irq.h |    6 ++++++
 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/xen/arch/arm/irq.c b/xen/arch/arm/irq.c
index 9c141bc..4e51fee 100644
--- a/xen/arch/arm/irq.c
+++ b/xen/arch/arm/irq.c
@@ -361,6 +361,10 @@ err:
     return rc;
 }
 
+/* Route an IRQ to a specific guest.
+ * For now the vIRQ is equal to the pIRQ and only SPIs are routabled to
+ * the guest.
+ */
 int route_irq_to_guest(struct domain *d, unsigned int irq,
                        const char * devname)
 {
@@ -369,6 +373,20 @@ int route_irq_to_guest(struct domain *d, unsigned int irq,
     unsigned long flags;
     int retval = 0;
 
+    if ( !is_routable_irq(irq) )
+    {
+        dprintk(XENLOG_G_ERR, "the IRQ%u is not routable\n", irq);
+        return -EINVAL;
+    }
+
+    if ( irq > vgic_num_irqs(d) )
+    {
+        dprintk(XENLOG_G_ERR,
+                "the IRQ number %u is too high for domain %u (max = %u)\n",
+                irq, d->domain_id, vgic_num_irqs(d));
+        return -EINVAL;
+    }
+
     action = xmalloc(struct irqaction);
     if (!action)
         return -ENOMEM;
@@ -379,6 +397,14 @@ int route_irq_to_guest(struct domain *d, unsigned int irq,
 
     spin_lock_irqsave(&desc->lock, flags);
 
+    if ( desc->arch.type == DT_IRQ_TYPE_INVALID )
+    {
+        dprintk(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
      *  - Otherwise -> For now, don't allow the IRQ to be shared between
@@ -392,10 +418,10 @@ int route_irq_to_guest(struct domain *d, unsigned int irq,
             goto out;
 
         if ( desc->status & IRQ_GUEST )
-            printk(XENLOG_ERR "ERROR: IRQ %u is already used by domain %u\n",
-                   irq, ad->domain_id);
+            dprintk(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);
+            dprintk(XENLOG_G_ERR, "IRQ %u is already used by Xen\n", irq);
         retval = -EBUSY;
         goto out;
     }
diff --git a/xen/include/asm-arm/gic.h b/xen/include/asm-arm/gic.h
index 8e37ccf..6e7375c 100644
--- a/xen/include/asm-arm/gic.h
+++ b/xen/include/asm-arm/gic.h
@@ -163,6 +163,8 @@
 #define DT_MATCH_GIC    DT_MATCH_COMPATIBLE("arm,cortex-a15-gic"), \
                         DT_MATCH_COMPATIBLE("arm,cortex-a7-gic")
 
+#define vgic_num_irqs(d)    ((d)->arch.vgic.nr_lines + 32)
+
 extern int domain_vgic_init(struct domain *d);
 extern void domain_vgic_free(struct domain *d);
 
diff --git a/xen/include/asm-arm/irq.h b/xen/include/asm-arm/irq.h
index e567f71..63926a5 100644
--- a/xen/include/asm-arm/irq.h
+++ b/xen/include/asm-arm/irq.h
@@ -37,6 +37,12 @@ void do_IRQ(struct cpu_user_regs *regs, unsigned int irq, 
int is_fiq);
 
 #define domain_pirq_to_irq(d, pirq) (pirq)
 
+static inline bool_t is_routable_irq(unsigned int irq)
+{
+    /* For now, we can only route SPIs to the guest */
+    return (irq >= NR_LOCAL_IRQS);
+}
+
 void init_IRQ(void);
 void init_secondary_IRQ(void);
 
-- 
1.7.10.4


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