Re: [Xen-devel] [PATCH 0 of 7] Mem event ring setup interface update

[Tim Deegan <tim@xxxxxxx>]

At 01:05 -0500 on 23 Feb (1329959105), Andres Lagar-Cavilla wrote:
> Update the interface for setting up mem event rings (for sharing, mem access 
> or
> paging).
> 
> Remove the "shared page", which was a waste of a whole page for a single event
> channel port value.
> 
> More importantly, both the shared page and the ring page were dom0 user-space
> process pages mapped by the hypervisor. If the dom0 process does not clean up,
> the hypervisor keeps posting events (and holding a map) to a page now 
> belonging
> to another process.
> 
> Solutions proposed:
> - Pass the event channel port explicitly as part of the domctl payload.
> - Reserve a pfn in the guest physmap for a each mem event ring. Set/retrieve
> these pfns via hvm params. Ensure they are set during build and restore, and
> retrieved during save. Ensure these pages don't leak and domains are left 
> zombie.
> 
> In all cases mem events consumers in-tree (xenpaging and xen-access) have been
> updated.
> 
> Updating the interface to deal with these problems requires
> backwards-incompatible changes on both the helper<->libxc and
> libxc<->hypervisor interfaces.
5A> 
> Take advantage of the interface update to plumb setting up of the sharing 
> ring,
> which was missing.
> 
> All patches touch x86/mm hypervisor bits. Patches 1, 3 and 5 are tools patches
> as well.
> 
> Signed-off-by: Andres Lagar-Cavilla <andres@xxxxxxxxxxxxxxxx>

For the Xen parts:
Acked-by: Tim Deegan <tim@xxxxxxx>

Cheers,

Tim.

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