Re: [Xen-devel] [PATCH v6 5/5] domain: use PGC_extra domheap page for shared_info

[Jan Beulich <jbeulich@xxxxxxxx>]

On 10.03.2020 18:49, paul@xxxxxxx wrote:
> From: Paul Durrant <pdurrant@xxxxxxxxxx>
> 
> Currently shared_info is a shared xenheap page but shared xenheap pages
> complicate future plans for live-update of Xen so it is desirable to,
> where possible, not use them [1]. This patch therefore converts shared_info
> into a PGC_extra domheap page. This does entail freeing shared_info during
> domain_relinquish_resources() rather than domain_destroy() so care is
> needed to avoid de-referencing a NULL shared_info pointer hence some
> extra checks of 'is_dying' are needed.
> 
> NOTE: For Arm, the call to free_shared_info() in arch_domain_destroy() is
>       left in place since it is idempotent and called in the error path for
>       arch_domain_create().
> 
> [1] See 
> https://lists.xenproject.org/archives/html/xen-devel/2020-02/msg02018.html
> 
> Signed-off-by: Paul Durrant <paul@xxxxxxx>
> ---
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien@xxxxxxx>
> Cc: Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Cc: George Dunlap <george.dunlap@xxxxxxxxxx>
> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> Cc: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> Cc: Wei Liu <wl@xxxxxxx>
> 
> v6:
>  - Drop dump_shared_info() but tag the shared info in the 'ExtraPage'
>    dump
> 
> v5:
>  - Incorporate new dump_shared_info() function
> 
> v2:
>  - Addressed comments from Julien
>  - Expanded the commit comment to explain why this patch is wanted
> ---
>  xen/arch/arm/domain.c      |  2 ++

Julien, Stefano? (I'd prefer to commit the entire series in one go,
rather than leaving out just this last patch.)

Jan