On Mon, Sep 18, 2017 at 05:27:52PM +0100, Julien Grall wrote: > The implementation of get_paged_frame is currently different whether the > architecture support sharing memory or paging memory. Both > version are extremely similar so it is possible to consolidate in a > single implementation. > > The main difference is the x86 version will allow grant on foreign page > when using HVM/PVH whilst Arm does not. At the moment, on x86 foreign pages > are only allowed for PVH Dom0. It seems that foreign pages should never > be granted so deny them > > The check for shared/paged memory are now gated with the respective ifdef. > Potentially, dummy p2m_is_shared/p2m_is_paging could be implemented for > Arm. > > Signed-off-by: Julien Grall <julien.gr...@arm.com> > > --- > > Cc: Andrew Cooper <andrew.coop...@citrix.com> > Cc: George Dunlap <george.dun...@eu.citrix.com> > Cc: Ian Jackson <ian.jack...@eu.citrix.com> > Cc: Jan Beulich <jbeul...@suse.com> > Cc: Konrad Rzeszutek Wilk <konrad.w...@oracle.com> > Cc: Stefano Stabellini <sstabell...@kernel.org> > Cc: Tim Deegan <t...@xen.org> > Cc: Wei Liu <wei.l...@citrix.com> > > Changes in v2: > - Deny grant on foreign page (aligned with the ARM code) > - Use #ifdef rather than #if defined > - Update commit message > - Fix typo in the title > > get_page_from_gfn will be able to get reference on foreign page and as > per my understanding will allow to grant page on foreign memory. > > This was not allowed with a simple get_page(...) on the ARM > implementation (no sharing nor paging supprot) but is allowed on the x86 > implementation due to get_page_from_gfn. > > On x86, foreign pages are currently only allowed for PVH dom0, so I > think it is not a big deal for now. > > On Arm, foreign pages can be present on any domain. So this patch would > permit grant on foreing pages. > > This patch will deny granting foreign pages. Jan Beulich is happy with > it. Any other opinions?
Won't this break QEMU running in stub domains? I haven't tested it, but I'm afraid QEMU running in a stub domain might try to grant a foreign frame. Ie: the emulated network code in QEMU might try to grant a foreign frame in order to forward operations from emulated devices to PV frontends. Roger. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
