Re: [PATCH 1/2] xen/arm: Defer request_irq on secondary CPUs after local_irq_enable

[Julien Grall <julien@xxxxxxx>]

Hi Henry,

The CC list doesn't seem to contain the other maintainers. Please use 
the scripts provided in the repo (such scripts/add_maintainers.pl) to 
generate the CC.
On 05/05/2022 03:54, Henry Wang wrote:
> With the enhanced ASSERT_ALLOC_CONTEXT, calling request_irq before
> local_irq_enable on secondary cores will lead to
>
> (XEN) Xen call trace:
> (XEN) [<000000000021d86c>] alloc_xenheap_pages+0x74/0x194 (PC)
> (XEN) [<000000000021d864>] alloc_xenheap_pages+0x6c/0x194 (LR)
> (XEN) [<0000000000229e90>] xmalloc_tlsf.c#xmalloc_pool_get+0x1c/0x28
> (XEN) [<000000000022a270>] xmem_pool_alloc+0x21c/0x448
> (XEN) [<000000000022a8dc>] _xmalloc+0x8c/0x290
> (XEN) [<000000000026b57c>] request_irq+0x40/0xb8
> (XEN) [<0000000000272780>] init_timer_interrupt+0x74/0xcc
> (XEN) [<000000000027212c>] start_secondary+0x1b4/0x238
> (XEN) [<0000000084000200>] 0000000084000200
> (XEN)
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 4:
> (XEN) Assertion '!in_irq() && (local_irq_is_enabled() ||
> num_online_cpus() <= 1)' failed at common/page_alloc.c:2212
> (XEN) ****************************************
>
> on systems without a big enough pool for xmalloc() to cater the
> requested size.
Can you explain in the commit message, why this is OK to move the code 
after enabling interrupts?
> Reported-by: Wei Chen <Wei.Chen@xxxxxxx>
> Suggested-by: Julien Grall <jgrall@xxxxxxxxxx>
> Signed-off-by: Henry Wang <Henry.Wang@xxxxxxx>
> Change-Id: Iebdde81f52785b0c6e037c981ff68922db016d08
> ---
>   xen/arch/arm/smpboot.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/xen/arch/arm/smpboot.c b/xen/arch/arm/smpboot.c
> index 7bfd0a73a7..a057e85ac1 100644
> --- a/xen/arch/arm/smpboot.c
> +++ b/xen/arch/arm/smpboot.c
> @@ -361,9 +361,6 @@ void start_secondary(void)
>   
>       init_secondary_IRQ();
>   
> -    init_maintenance_interrupt();
> -    init_timer_interrupt();
> -
>       set_current(idle_vcpu[cpuid]);
>   
>       setup_cpu_sibling_map(cpuid);
> @@ -380,6 +377,10 @@ void start_secondary(void)
>       cpumask_set_cpu(cpuid, &cpu_online_map);
>   
>       local_irq_enable();
> +
> +    init_maintenance_interrupt();
> +    init_timer_interrupt();
> +
>       local_abort_enable();
>   
>       check_local_cpu_errata();
Cheers,

--
Julien Grall