[RFC 8/8] xen/arm: acpi: route all unused IRQs to DOM0

[Julien Grall <julien.grall@arm.com>]

It is not possible to know which IRQs will be used by DOM0 when ACPI is
inuse. The approach implemented by this patch, will route all unused
IRQs to DOM0 before it has booted.

The number of IRQs routed is based on the maximum SPIs supported by the
hardware (up to ~1000). However, some of them might not be wired. So we
would allocate resource for nothing.

For each IRQ routed, Xen is allocating memory for irqaction (40 bytes)
and irq_guest (16 bytes). So in the worst case scenario ~54KB of memory
will be allocated. Given that ACPI will mostly be used by server, I
think it is a small drawback.

map_irq_to_domain is slightly reworked to remove the dependency on
device-tree. So the function can be also be used for ACPI and will
avoid code duplication.

Signed-off-by: Julien Grall <julien.grall@arm.com>
---
 xen/arch/arm/domain_build.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 00dc07a..76d503d 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -953,11 +953,10 @@ static int make_timer_node(const struct domain *d, void *fdt,
     return res;
 }
 
-static int map_irq_to_domain(const struct dt_device_node *dev,
-                             struct domain *d, unsigned int irq)
+static int map_irq_to_domain(struct domain *d, unsigned int irq,
+                             bool_t need_mapping, const char *devname)
 
 {
-    bool_t need_mapping = !dt_device_for_passthrough(dev);
     int res;
 
     res = irq_permit_access(d, irq);
@@ -977,7 +976,7 @@ static int map_irq_to_domain(const struct dt_device_node *dev,
          */
         vgic_reserve_virq(d, irq);
 
-        res = route_irq_to_guest(d, irq, irq, dt_node_name(dev));
+        res = route_irq_to_guest(d, irq, irq, devname);
         if ( res < 0 )
         {
             printk(XENLOG_ERR "Unable to map IRQ%"PRId32" to dom%d\n",
@@ -997,6 +996,7 @@ static int map_dt_irq_to_domain(const struct dt_device_node *dev,
     struct domain *d = data;
     unsigned int irq = dt_irq->irq;
     int res;
+    bool_t need_mapping = !dt_device_for_passthrough(dev);
 
     if ( irq < NR_LOCAL_IRQS )
     {
@@ -1015,7 +1015,7 @@ static int map_dt_irq_to_domain(const struct dt_device_node *dev,
         return res;
     }
 
-    res = map_irq_to_domain(dev, d, irq);
+    res = map_irq_to_domain(d, irq, need_mapping, dt_node_name(dev));
 
     return 0;
 }
@@ -1152,7 +1152,7 @@ static int handle_device(struct domain *d, struct dt_device_node *dev)
             return res;
         }
 
-        res = map_irq_to_domain(dev, d, res);
+        res = map_irq_to_domain(d, res, need_mapping, dt_node_name(dev));
         if ( res )
             return res;
     }
@@ -1411,13 +1411,10 @@ static int acpi_permit_spi_access(struct domain *d)
         if ( desc->action != NULL)
             continue;
 
-        res = irq_permit_access(d, i);
+        /* XXX: Shall we use a proper devname? */
+        res = map_irq_to_domain(d, i, true, "ACPI");
         if ( res )
-        {
-            printk(XENLOG_ERR "Unable to permit to dom%u access to IRQ %u\n",
-                   d->domain_id, i);
             return res;
-        }
     }
 
     return 0;
-- 
1.9.1


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