Re: [Xen-devel] [PATCH v4 6/6] domain: use PGC_extra domheap page for shared_info

["Durrant, Paul" <pdurrant@xxxxxxxxxxxx>]

> -----Original Message-----
> From: paul@xxxxxxx <paul@xxxxxxx>
> Sent: 09 March 2020 09:35
> To: xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: Durrant, Paul <pdurrant@xxxxxxxxxxxx>; Paul Durrant <paul@xxxxxxx>; 
> Stefano Stabellini
> <sstabellini@xxxxxxxxxx>; Julien Grall <julien@xxxxxxx>; Volodymyr Babchuk
> <Volodymyr_Babchuk@xxxxxxxx>; Andrew Cooper <andrew.cooper3@xxxxxxxxxx>; 
> George Dunlap
> <george.dunlap@xxxxxxxxxx>; Ian Jackson <ian.jackson@xxxxxxxxxxxxx>; Jan 
> Beulich <jbeulich@xxxxxxxx>;
> Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; Wei Liu <wl@xxxxxxx>
> Subject: [PATCH v4 6/6] domain: use PGC_extra domheap page for shared_info
> 
> 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>

I realise I forgot to fold in the new dump function for shared_info (needed 
since it will no longer feature in the dump of xen pages) so I will send a v5 
of this series shortly.

  Paul

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