Re: [Xen-devel] [PATCH 0 of 5] Add support for mapping grant references into HVM guests (+ some cleanup)

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

Hi. Some comments.

- Patch 4 adds a new grant hypercall, but the current
  GNTTABOP_map_grant_ref can be used, I suppose. Why not to use
  gnttab_map_grant_ref::host_addr?

- It seems that the patch 4 touches common code unnecessary.
  it would suffice to touch create_grant_host_mapping() and
  replace_grant_host_mapping() inserting something like
  "if (hvm_domain) return hvm_domain_case()".

Then, your modification will be well separated so that the
possibility for inclusion would increase.

thanks,
  
On Tue, May 19, 2009 at 12:27:02PM +0100, steven.smith@xxxxxxxxxxxxx wrote:
> Add support for mapping grant references into HVM domains, by modifying
> the P2M table.
> 
> The first couple of patches just tidy up the current grant table
> implementation a bit, fixing a couple of bugs in the process, and
> should be fairly uncontroversial.  The fourth patch in the series adds
> a new HVM op to Xen which allows a HVM guest to map a remote domain's
> grant reference into its P2M table, which can then be mapped by the
> pagetables in the usual way.  The final patch adds matching support to
> the Linux unmodified drivers tree, allowing the new operation to
> actually be used, and also adds a couple of very simple test modules.
> 
> This isn't actually terribly useful as it stands, because there are no
> realistic consumers of this interface.  I wrote it mostly for the
> benefit of our closed-source Windows drivers, but that obviously
> doesn't help people on the list very much.  I'm not quite sure what
> the best way of handling this is; it's clearly better for us for
> this stuff to go into xen-unstable, rather than being maintained as an
> out-of-tree patch forever, and it'd be a bit of a waste to force
> anyone else who wanted this functionality to reinvent it, but it seems
> odd to add an interface which has no publicly available consumers.
> 
> 
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-- 
yamahata

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