RE: [Xen-devel] Regressions in v3.3-rc1 introduced by"xen/granttable: Grant tables V2 implementation"

From: Ian Campbell
Date: Wed Jan 25 2012 - 10:48:18 EST


On Wed, 2012-01-25 at 15:16 +0000, Paul Durrant wrote:
> > -----Original Message-----
> >
> > On HVM for gnttab_shared we make an add_to_physmap call with
> > XENMAPSPACE_grant_table (in gnttab_map). I don't see any support call to
> > do something similar for the status array though and I don't see a
> > XENMAPSPACE_* specifically for that case either in the hypervisor either.
> >
>
> There is no map-space for the status pages. To map them you use the
> standard map space but OR a bit (top bit IIRC) into in the idx. It's a
> bit icky, but that's how it is.

I can't see that happening anywhere in the current Linux tree, there's
only one call to XENMAPSPACE_grant_table and it doesn't set the top bit,
so presumably this is at least part of the problem.

I hope that "top bit" is consistent for 32 and 64 bit domains....

Ian.

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