Re: [Xen-devel] [PATCH v2] arm/p2m: Fix regression during domain shutdown with active mem_access

[Julien Grall <julien.grall@xxxxxxx>]

Hello Tamas,

On 25/01/2017 00:16, Tamas K Lengyel wrote:
> The change in commit 438c5fe4f0c introduced a regression for domains where
> mem_acces is or was active. When relinquish_p2m_mapping attempts to clear
> a page where the order is not 0 the following ASSERT is triggered:
>
>     ASSERT(!p2m->mem_access_enabled || page_order == 0);
>
> This regression was unfortunately not caught during testing in preparation
> for the 4.8 release.
>
> In this patch we adjust the ASSERT to not trip when the domain
> is being shutdown.
>
> Ideally this fix would be part of Xen 4.8.1.
>
> Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxxxxx>
> ---
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
>
> v2: Add dying domain check to assert
> ---
>  xen/arch/arm/p2m.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 09ceb378a5..d9fdfe9a2e 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -993,7 +993,8 @@ static int __p2m_set_entry(struct p2m_domain *p2m,
>       * The radix-tree can only work on 4KB. This is only used when
>       * memaccess is enabled.
Please update the comment to reflect the change in the assert.

>       */
> -    ASSERT(!p2m->mem_access_enabled || page_order == 0);
> +    ASSERT(!p2m->mem_access_enabled || page_order == 0 ||
> +           p2m->domain->is_dying == DOMDYING_dying);
You don't need to check the value of is_dying. p2m->domain->is_dying is 
enough here.
>      /*
>       * The access type should always be p2m_access_rwx when the mapping
>       * is removed.
Cheers,

--
Julien Grall

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