Re: [PATCH v4.2] xen/p2m: put reference for level 2 superpage

[Julien Grall <julien@xxxxxxx>]

Hi Luca,

On 28/05/2024 13:56, Luca Fancellu wrote:
> From: Penny Zheng <Penny.Zheng@xxxxxxx>
>
> We are doing foreign memory mapping for static shared memory, and
> there is a great possibility that it could be super mapped.
> But today, p2m_put_l3_page could not handle superpages.
>
> This commits implements a new function p2m_put_l2_superpage to handle
> level 2 superpages, specifically for helping put extra references for
> foreign superpages.
>
> Modify relinquish_p2m_mapping as well to take into account preemption
> when we have a level-2 foreign mapping.
>
> Currently level 1 superpages are not handled because Xen is not
> preemptible and therefore some work is needed to handle such superpages,
> for which at some point Xen might end up freeing memory and therefore
> for such a big mapping it could end up in a very long operation.
>
> Signed-off-by: Penny Zheng <penny.zheng@xxxxxxx>
> Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall