[Xen-devel] [PATCH] xen/arm: Don't unflatten DT when booting with ACPI

[Punit Agrawal <punit.agrawal@xxxxxxx>]

Unflattening the device tree when booting with "acpi=force" leads to the
following stack trace on AMD Seattle platform -

(XEN) Xen call trace:
(XEN)    [<0000000000204bfc>] dt_irq_translate+0x48/0x58 (PC)
(XEN)    [<0000000000204f5c>] dt_device_get_irq+0x34/0x38 (LR)
(XEN)    [<0000000000251a08>] platform_get_irq+0x14/0x44
(XEN)    [<00000000002952bc>] smmu.c#arm_smmu_dt_init+0x190/0x100c
(XEN)    [<0000000000299310>] device_init+0xa8/0xdc
(XEN)    [<00000000002950f0>] iommu_hardware_setup+0x34/0x68
(XEN)    [<0000000000294ef0>] iommu_setup+0x48/0x1c8
(XEN)    [<000000000029cecc>] start_xen+0xb94/0xd34
(XEN)    [<00000083fbba91dc>] 00000083fbba91dc

The problem arises due to the unflattened device tree being
unconditionally used in iommu_hardware_setup().

Let's re-arrange the code without changing boot order to unflatten the
device tree only when acpi is disabled.

Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxx>
---
 xen/arch/arm/setup.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
index 92a2de6b70..4d62ea8157 100644
--- a/xen/arch/arm/setup.c
+++ b/xen/arch/arm/setup.c
@@ -753,16 +753,18 @@ void __init start_xen(unsigned long boot_phys_offset,
     /* Parse the ACPI tables for possible boot-time configuration */
     acpi_boot_table_init();
 
+    end_boot_allocator();
+
+    vm_init();
+
     if ( acpi_disabled )
+    {
         printk("Booting using Device Tree\n");
+       dt_unflatten_host_device_tree();
+    }
     else
         printk("Booting using ACPI\n");
 
-    end_boot_allocator();
-
-    vm_init();
-    dt_unflatten_host_device_tree();
-
     init_IRQ();
 
     platform_init();
-- 
2.11.0


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