Re: [Xen-devel] [PATCH v3 04/16] hypervisor part of add vmware_port to xl.cfg

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 08/09/14 16:22, Jan Beulich wrote:
>>>> On 08.09.14 at 17:01, <boris.ostrovsky@xxxxxxxxxx> wrote:
>> I wonder whether we should enable #GP intercepts only when we know that 
>> the guest is VMware-aware (which we do as far as I can tell since we 
>> have a config option).
> I didn't look at the patches themselves yes, but I very much expected
> this to now be the case considering discussion on the earlier version.
> If it's not, I'm not even sure looking at the new version is going to be
> of much use...
>
> Jan
>

I find it incredibly hard to believe that VMWare do unconditional #GP
exits, and looking at the Intel manual, you do not actually need to
intercept #GP faults.

The "unconditional I/O exiting" control can be used to cherry-pick
specific IO ports in combination with the IO port bitmap, ahead of the
#GP fault due to a failure of IOPL.  I would expect AMD has a similar
option.

~Andrew


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