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

[Shannon Zhao <zhaoshenglong@xxxxxxxxxx>]

On 2016/7/6 18:12, Stefano Stabellini wrote:
> 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@xxxxxxxxxx>
>>>>> > > > > 
>>>>> > > > > Copy all the ACPI tables to guest space so that UEFI or guest 
>>>>> > > > > could
>>>>> > > > > access them.
>>>>> > > > > 
>>>>> > > > > Signed-off-by: Shannon Zhao <shannon.zhao@xxxxxxxxxx>
>>>>> > > > > ---
>>>>> > > > >   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.
Sorry, I'm not sure understand this. I found the b_info->max_memkb but
didn't find the slack you said. And how to fix this? Update
b_info->max_memkb or the slack?

Thanks,
-- 
Shannon


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