> -----Original Message----- > From: Julien Grall [mailto:julien.gr...@linaro.org] > Sent: 20 October 2017 11:00 > To: Paul Durrant <paul.durr...@citrix.com>; 'Jan Beulich' > <jbeul...@suse.com> > 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>; 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 > > 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. > >> > >
Hi Julien, > > 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(). The guest would not be able to map them if they were not assigned in some way! See the code block at http://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=xen/common/grant_table.c;hb=HEAD#l1716 It calls gnttab_create_shared_page() which is what calls through to 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. > That makes sense. Do you still have any issues with this patch apart from the cosmetic ones you spotted in the header? Cheers, Paul > Cheers, > > -- > Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
