Re: [PATCH v3 3/7] xen/p2m: put reference for level 2 superpage

[Michal Orzel <michal.orzel@amd.com>]

Hi Luca,

On 22/05/2024 09:51, Luca Fancellu wrote:
> 
> 
> From: Penny Zheng <Penny.Zheng@arm.com>
> 
> 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
> 2MB superpages, specifically for helping put extra references for
> foreign superpages.
> 
> Modify relinquish_p2m_mapping as well to take into account preemption
> when type is foreign memory and order is above 9 (2MB).
> 
> Currently 1GB 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@arm.com>
> Signed-off-by: Luca Fancellu <luca.fancellu@arm.com>
Reviewed-by: Michal Orzel <michal.orzel@amd.com>

~Michal