Re: [PATCH v2 16/17] libxc/xc_dom_arm: Copy ACPI tables to guest space

[Stefano Stabellini <sstabellini@kernel.org>]

On Wed, 6 Jul 2016, Julien Grall wrote:
> Hi Stefano,
> 
> On 05/07/16 18:13, Stefano Stabellini wrote:
> > On Thu, 23 Jun 2016, Julien Grall wrote:
> > > On 23/06/2016 04:17, Shannon Zhao wrote:
> > > > From: Shannon Zhao <shannon.zhao@linaro.org>
> > > > 
> > > > Copy all the ACPI tables to guest space so that UEFI or guest could
> > > > access them.
> > > > 
> > > > Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
> > > > ---
> > > >   tools/libxc/xc_dom_arm.c | 51
> > > > ++++++++++++++++++++++++++++++++++++++++++++++++
> > > >   1 file changed, 51 insertions(+)
> > > > 
> > > > diff --git a/tools/libxc/xc_dom_arm.c b/tools/libxc/xc_dom_arm.c
> > > > index 64a8b67..6a0a5b7 100644
> > > > --- a/tools/libxc/xc_dom_arm.c
> > > > +++ b/tools/libxc/xc_dom_arm.c
> > > > @@ -63,6 +63,47 @@ static int setup_pgtables_arm(struct xc_dom_image
> > > > *dom)
> > > > 
> > > >   /*
> > > > ------------------------------------------------------------------------
> > > > */
> > > > 
> > > > +static int xc_dom_copy_acpi(struct xc_dom_image *dom)
> > > > +{
> > > > +    int rc, i;
> > > > +    uint32_t pages_num = ROUNDUP(dom->acpitable_size, XC_PAGE_SHIFT) >>
> > > > +                         XC_PAGE_SHIFT;
> > > > +    const xen_pfn_t base = GUEST_ACPI_BASE >> XC_PAGE_SHIFT;
> > > > +    xen_pfn_t *p2m;
> > > > +    void *acpi_pages;
> > > > +
> > > > +    p2m = malloc(pages_num * sizeof(*p2m));
> > > > +    for (i = 0; i < pages_num; i++)
> > > > +        p2m[i] = base + i;
> > > > +
> > > > +    rc = xc_domain_populate_physmap_exact(dom->xch, dom->guest_domid,
> > > > +                                          pages_num, 0, 0, p2m);
> > > 
> > > Hmmmm... it looks like this is working because libxl is setting the
> > > maximum
> > > size of the domain with some slack (1MB). However, I guess the slack was
> > > for
> > > something else. Wei, Stefano, Ian, can you confirm?
> > 
> > If I recall correctly, the slack is a magic value coming from the
> > ancient history of toolstacks.
> 
> Does it mean we would need to update the slack to take into account the ACPI
> blob?

Yes, we need to take into account the ACPI blob. Probably not in the
slack but directly in mam_memkb.

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