Re: [PATCH v11 6/9] xen: Add ring 3 vmware_port support

[Don Slutz <dslutz@verizon.com>]

On 06/05/15 06:54, Ian Campbell wrote:
> On Fri, 2015-06-05 at 10:31 +0100, Jan Beulich wrote:
>>> I'm talking about cost-benefits analysis.  What's the benefit of
>>> accepting this patch, and is it worth the cost?
>>
>> The basic idea of allowing guests originally having got installed on
>> VMware to continue their lives on Xen is certainly something worth
>> accepting some cost. It's really hard to judge whether in the case
>> here things go too far (and that would equally apply to the hand
>> crafted instruction decoding done in earlier versions of this series).
> 
> I can see the benefit in having a guest which was installed on vmware be
> able to boot and work on Xen.
> 
> But AIUI this userspace vmware port thing is not needed for that basic
> use case but instead goes farther and enables advanced features like
> clip boards integration, which TBH I think we could consider living
> without (especially considering the costs discussed here).
> 
> It would be really useful to see a comprehensive list of exactly what
> guest ring3 access to the vmware port actually enables i.e. a list of
> specific features which require it.

Ok, I have done some testing.  Here is what I know:

Without ring3 support:

1) VMware tools will not install on linux and windows.
2) open-vm-tools (https://github.com/vmware/open-vm-tools) will not
install (how ever it is not hard to change it to do so, you need to add
a call to iopl(3) need to be added in a few places) on linux

However if VMware tools did get installed on the window disk bits
somehow, the VMware mouse support works.  Linux gets this because Xorg
detects and uses the VMware mouse under IOPL(3).


The following are available via QEMU 2.4 (if the patches get accepted)
and a functioning open-vm-tools:

3) The ability to perform virtual machine power operations gracefully is
missing. (code to access QEMU's from Xen to do this is missing).  I.E.
get windows to shutdown when requested!

4) Execution of VMware provided or user configured scripts in guests
during various power operations.

5) Clock synchronization between guests and hosts or client desktops.

6) Access to VMware guest info variables (code to access QEMU's from Xen
to do this is missing).  This can be used to customize guest operating
systems immediately after powering on virtual machines. It can also be
used to monitor the health of a guest.


   -Don Slutz



> 
> Ian.
>