Currently, the vGIC is not able to cope with hardware PPIs routed to guests.
One of the solutions to this problem is to skip any device that uses PPI
source completely while building the domain itself.

This patch goes through all the interrupt sources of a device and skip it
if one of the interrupts sources is a PPI. It fixes XEN boot on i.MX8MQ by
skipping the PMU node.

Suggested-by:  Julien Grall <julien.grall@arm.com>
Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>
---
Changes since v2:
    * Update subject-line for the patch.
    * Fix commit message.
    * Add proper comments for changes.

Changes since v1:
    * Added comment for PPIs range.
---
 xen/arch/arm/domain_build.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index d983677..53935f8 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1353,7 +1353,7 @@ static int __init handle_node(struct domain *d, struct kernel_info *kinfo,
         { /* sentinel */ },
     };
     struct dt_device_node *child;
-    int res;
+    int res, i, nirq, irq_id;
     const char *name;
     const char *path;
 
@@ -1400,6 +1400,24 @@ static int __init handle_node(struct domain *d, struct kernel_info *kinfo,
     }
 
     /*
+     * The vGIC does not support routing hardware PPIs to guest. So
+     * we need to skip any node using PPIs.
+     */
+    nirq = dt_number_of_irq(node);
+
+    for ( i = 0 ; i < nirq ; i++ )
+    {
+        irq_id = platform_get_irq(node, i);
+
+        /* PPIs ranges from ID 16 to 31 */
+        if ( irq_id >= 16 && irq_id < 32 )
+        {
+            dt_dprintk(" Skip it(using PPIs)\n");
+            return 0;
+        }
+    }
+
+    /*
      * Xen is using some path for its own purpose. Warn if a node
      * already exists with the same path.
      */
-- 
2.7.4


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Hi Amit,

On 6/23/19 1:56 PM, Amit Singh Tomar wrote:
> Currently, the vGIC is not able to cope with hardware PPIs routed to guests.
> One of the solutions to this problem is to skip any device that uses PPI
> source completely while building the domain itself.
> 
> This patch goes through all the interrupt sources of a device and skip it
> if one of the interrupts sources is a PPI. It fixes XEN boot on i.MX8MQ by
> skipping the PMU node.
> 
> Suggested-by:  Julien Grall <julien.grall@arm.com>
> Signed-off-by: Amit Singh Tomar <amittomer25@gmail.com>

With one minor change (see below):

Acked-by: Julien Grall <julien.grall@arm.com>


> @@ -1400,6 +1400,24 @@ static int __init handle_node(struct domain *d, struct kernel_info *kinfo,
>       }
>   
>       /*
> +     * The vGIC does not support routing hardware PPIs to guest. So
> +     * we need to skip any node using PPIs.
> +     */
> +    nirq = dt_number_of_irq(node);
> +
> +    for ( i = 0 ; i < nirq ; i++ )
> +    {
> +        irq_id = platform_get_irq(node, i);
> +
> +        /* PPIs ranges from ID 16 to 31 */
> +        if ( irq_id >= 16 && irq_id < 32 )
> +        {
> +            dt_dprintk(" Skip it(using PPIs)\n");

NIT: missing space after "it". I can fix this on commit.

Cheers,

-- 
Julien Grall

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