Re: [PATCH v3 2/2] xen/common: Use enhanced ASSERT_ALLOC_CONTEXT in xmalloc()

[Julien Grall <julien@xen.org>]

Hi,

On 07/05/2022 03:54, Henry Wang wrote:
> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
> index e866e0d864..ea59cd1a4a 100644
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -162,13 +162,6 @@
>   static char __initdata opt_badpage[100] = "";
>   string_param("badpage", opt_badpage);
>   
> -/*
> - * Heap allocations may need TLB flushes which may require IRQs to be
> - * enabled (except when only 1 PCPU is online).
> - */
> -#define ASSERT_ALLOC_CONTEXT() \
> -    ASSERT(!in_irq() && (local_irq_is_enabled() || num_online_cpus() <= 1))
> -
FYI, the patch introducing ASSERT_ALLOC_CONTEXT() has been reverted. I 
intend to re-introduce it once your previous patch and the one fixing 
the ITS (not yet formally sent) have been committed.

I have also checked that none of the ASSERTs() would be triggered on my 
x86 setup. So:

Tested-by: Julien Grall <jgrall@amazon.com>
Acked-by: Julien Grall <jgrall@amazon.com>

On a side note (no action expected for you), I noticed that the 
ASSERT()s would only trigger from CPU2 and onwards at least for Arm. 
This is because num_online_cpus() would still be 1 when bringing-up CPU1.

I went through the original discussion and I am not sure why we switched 
from < SYS_STATE_smp_boot to num_online_cpus() (aside that Arm doesn't 
set it). Aynway, this is not a major issue here as this is an ASSERT().

Cheers,

-- 
Julien Grall