Re: [Xen-devel] Question about xenpage_list

[Tamas K Lengyel <tamas.k.lengyel@xxxxxxxxx>]

On Wed, Aug 28, 2019 at 9:35 AM Jan Beulich <jbeulich@xxxxxxxx> wrote:
>
> On 28.08.2019 17:28, Tamas K Lengyel wrote:
> > Hi all,
> > I'm trying to track down how a call in common/grant_table.c to
> > share_xen_page_with_guest will actually populate that page into the
> > guest's physmap. Immediately after the call the page doesn't seem to
> > be present in the physmap, as share_xen_page_with_guest will just add
> > the page to the domain's xenpage_list linked-list:
> >
> >         unsigned long mfn;
> >         unsigned long gfn;
> >
> >         share_xen_page_with_guest(virt_to_page(gt->shared_raw[i]), d, 
> > SHARE_rw);
> >
> >         mfn = virt_to_mfn(gt->shared_raw[i]);
> >         gfn = mfn_to_gmfn(d, mfn);
> >
> >         gdprintk(XENLOG_INFO, "Sharing %lx -> %lx with domain %u\n",
> > gfn, mfn, d->domain_id);
> >
> > This results in the following:
> >
> > (XEN) grant_table.c:1820:d0v0 Sharing ffffffffffffffff -> 42c71e with 
> > domain 1
> >
> > AFAICT the page only gets populated into the physmap once the domain
> > gets unpaused. If I let the domain run and then pause it I can see
> > that the page is in the guest's physmap (by looping through all the
> > entries in its EPT):
> >
> > (XEN) mem_sharing.c:1636:d0v0 0xf2000 -> 0x42c71e is a grant mapping
> > shared with the guest
>
> This should be the result of the domain having made a respective
> XENMAPSPACE_grant_table request, shouldn't it?
>

Do you mean the guest itself or the toolstack?

Tamas

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