Hi Paul,
On 20/10/17 09:26, Paul Durrant wrote:
-----Original Message-----
From: Jan Beulich [mailto:jbeul...@suse.com]
Sent: 20 October 2017 07:25
To: Julien Grall <julien.gr...@linaro.org>
Cc: Julien Grall <julien.gr...@arm.com>; Andrew Cooper
<andrew.coop...@citrix.com>; George Dunlap
<george.dun...@citrix.com>; Ian Jackson <ian.jack...@citrix.com>; Paul
Durrant <paul.durr...@citrix.com>; Roger Pau Monne
<roger....@citrix.com>; Wei Liu <wei.l...@citrix.com>; Stefano Stabellini
<sstabell...@kernel.org>; xen-de...@lists.xenproject.org; Konrad Rzeszutek
Wilk <konrad.w...@oracle.com>; Daniel De Graaf <dgde...@tycho.nsa.gov>;
Tim (Xen.org) <t...@xen.org>
Subject: Re: [Xen-devel] [PATCH v12 05/11] x86/mm: add
HYPERVISOR_memory_op to acquire guest resources
On 19.10.17 at 18:21, <julien.gr...@linaro.org> wrote:
Looking a bit more at the resource you can acquire from this hypercall.
Some of them are allocated using alloc_xenheap_page() so not assigned to
a domain.
So I am not sure how you can expect a function set_foreign_p2m_entry to
take reference in that case.
Hmm, with the domain parameter added, DOMID_XEN there (for
Xen heap pages) could identify no references to be taken, if that
was really the intended behavior in that case. However, even for
Xen heap pages life time tracking ought to be done - it is for a
reason that share_xen_page_with_guest() assigns the target
domain as the owner of such pages, as that allows get_page() to
succeed for them.
So, nothing I'm doing here is making anything worse, right? Grant tables are
assigned to the guest, and IOREQ server pages are allocated with
alloc_domheap_page() so nothing is anonymous.
I don't think grant tables is assigned to the guest today. They are
allocated using xenheap_pages() and I can't find
share_xen_page_with_guest().
Anyway, I discussed with Stefano about it. set_foreign_p2m_entry is
going to be left unimplemented on Arm until someone as time to implement
correctly the function.
Cheers,
--
Julien Grall
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