Re: [Xen-devel] [PATCH v2 for-4.9] xen/arm: Don't unflatten DT when booting with ACPI

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 21 Apr 2017, Punit Agrawal wrote:
> 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>
> Reviewed-by: Julien Grall <julien.grall@xxxxxxx>


Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>

and committed


> ---
> v1 -> v2
> * Changed tab to spaces
> * Added tag
> ---
>  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..046905f6c3 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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