Re: [Xen-devel] Question about xenpage_list

[Jan Beulich <jbeulich@xxxxxxxx>]

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?

Jan

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