Re: [Xen-devel] [PATCH v4 3/9] xen/arm: Implement set_memory_map hypercall for arm

[Eugene Fedotov <e.fedotov@xxxxxxxxxxx>]

11.10.2013 14:09, Ian Campbell:
> On Fri, 2013-10-11 at 14:06 +0400, Eugene Fedotov wrote:
> > 10.10.2013 14:56, Ian Campbell:
> > > On Fri, 2013-10-04 at 13:43 +0900, Jaeyong Yoo wrote:
> > > > From: Evgeny Fedotov <e.fedotov@xxxxxxxxxxx>
> > > >
> > > > When creating domU in toolstack, pass the guest memory
> > > > map info to the hypervisor, and the hypervisor stores those info in
> > > > arch_domain for later use.
> > > >
> > > > Singed-off-by: Evgeny Fedotov <e.fedotov@xxxxxxxxxxx>
> > > > ---
> > > >    tools/libxc/xc_dom_arm.c     | 12 +++++++-
> > > >    tools/libxc/xc_domain.c      | 44 ++++++++++++++++++++++++++++
> > > >    tools/libxc/xenctrl.h        | 23 +++++++++++++++
> > > >    xen/arch/arm/domain.c        |  3 ++
> > > >    xen/arch/arm/mm.c            | 68 
> > > > ++++++++++++++++++++++++++++++++++++++++++++
> > > >    xen/include/asm-arm/domain.h |  2 ++
> > > >    xen/include/asm-arm/mm.h     |  1 +
> > > >    xen/include/public/memory.h  | 15 ++++++++--
> > > >    xen/include/xsm/dummy.h      |  5 ++++
> > > >    xen/include/xsm/xsm.h        |  5 ++++
> > > >    10 files changed, 175 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
> > > > index df59ffb..20c9095 100644
> > > > --- a/tools/libxc/xc_dom_arm.c
> > > > +++ b/tools/libxc/xc_dom_arm.c
> > > > @@ -166,6 +166,7 @@ int arch_setup_meminit(struct xc_dom_image *dom)
> > > >    {
> > > >        int rc;
> > > >        xen_pfn_t pfn, allocsz, i;
> > > > +    struct dt_mem_info memmap;
> > > >    
> > > >        dom->shadow_enabled = 1;
> > > >    
> > > > @@ -191,7 +192,16 @@ int arch_setup_meminit(struct xc_dom_image *dom)
> > > >                0, 0, &dom->p2m_host[i]);
> > > >        }
> > > >    
> > > > -    return 0;
> > > > +    /* setup guest memory map */
> > > > +    memmap.nr_banks = 2;
> > > > +    memmap.bank[0].start = (dom->rambase_pfn << PAGE_SHIFT_ARM);
> > > > +    memmap.bank[0].size = (dom->total_pages << PAGE_SHIFT_ARM);
> > > > +    /*The end of main memory: magic pages */
> > > > +    memmap.bank[1].start = memmap.bank[0].start + memmap.bank[0].size;
> > > > +    memmap.bank[1].size = NR_MAGIC_PAGES << PAGE_SHIFT_ARM;
> > > Are the 0 and 1 here hardcoded magic numbers?
> > Well, we hardcoded here two memory regions: the first one for RAM, the
> > second one for "magic pages".
> > > > +    return xc_domain_set_memory_map(dom->xch, dom->guest_domid, &memmap);
> > > I think this is using set_memory_map in a different way to it is used
> > > for x86 (where it gives the PV e820 map, a PV version of a BIOS provided
> > > datastructure).
> > Do you mean that using e820 structure for ARM implementation is better
> > than dt_mem_info structure (that has been taken from libdt) and should
> > be used in ARM implementation of get/set memory map?
> I mean on x86 it is used as a way of communicating a memory map (in a
> structure vaguely like an actual defined architecture specific layout,
> the e820), whereas on ARM it is only used by the tools and should not be
> exposed to the guest, since the guest gets its info from the DTB.
>
> > > The guest should get its memory map via DTB not via a PV hypercall. I
> > > know the guest isn't using get_memory_map but I don't think we should
> > > even make it available.
> > OK, this hypercall will be available from dom0 only.
> It'll have to move away from the XENMEM space then.
Can we create new DOMCTL hypercall for get/set memory map?



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