Re: [Xen-devel] PVH hypercall interface

[Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>]

On Mon, Aug 08, 2016 at 01:19:43PM +0200, Roger Pau Monne wrote:
> On Mon, Aug 08, 2016 at 11:42:03AM +0100, Andrew Cooper wrote:
> > On 08/08/16 11:21, Marek Marczykowski-Górecki wrote:
> > > Hi,
> > >
> > > What hypercalls are available for PVH guests?
> > 
> > First of all, be aware that there is currently some chaos in the
> > codebase which is soon to be resolved.
> > 
> > What you are looking for is HVMLite, which will likely be renamed to PVH
> > once it is complete.  Original PVH will then be filed in /dev/null,
> > leaving only a set of lessons in git history.
> > 
> > > How is it different for HVM guests?
> > 
> > HVMLite guests are just HVM guests without qemu.
> > 
> > Roger (CC'd) is leading the effort.  You select an HVMLite guest by
> > choosing device-model = None in the xl configuration file, rather than
> > setting pvh=1
> > 
> > > Is it documented somewhere?
> > 
> > There are patches on the list.
> > 
> > Also, docs/misc/hvmlite.markdown
> > 
> > > For example I'd expect that do_mmu_update is available only for PV
> > > guests, but looking at the code I can't find anything preventing other
> > > guest types from using it (no, some obscure conditions deep in execution
> > > path doesn't count).
> > 
> > HVM guests use the hvm_hypercall_table, not the hypercall tables in entry.S
> 
> They have access to the same set of hypercalls as HVM guests, in fact the 
> hypercall table is shared between HVM and HVMlite guests (to become PVH, 
> just using HVMlite here to avoid confusion). Classic PVH guests had their 
> own hypercall table, but as Andrew said you should not look at those.

Thanks for the explanation. What is the current state of HVMlite? I see
"none" is valid value for "device_model_version" already, but if I try
to start such guest, it fails at x86_compat call (tries to boot it as PV
guest). I guess it's because of missing kernel support. Is "[PATCH v2
00/11] HVMlite domU support" sent in Feb the latest version available?
When it is planned to have it in vanilla kernel?


-- 
Best Regards,
Marek Marczykowski-Górecki
Invisible Things Lab
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?

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