lkml.org 
[lkml]   [2007]   [Sep]   [14]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateFri, 14 Sep 2007 16:46:30 -0500
FromAnthony Liguori <>
SubjectRe: [kvm-devel] [PATCH] Refactor hypercall infrastructure
Jeremy Fitzhardinge wrote:
> Anthony Liguori wrote:
> 
>> The whole point of using the instruction is to allow hypercalls to be
>> used in many locations.  This has the nice side effect of not
>> requiring a central hypercall initialization routine in the guest to
>> fetch the hypercall page.  A PV driver can be completely independent
>> of any other code provided that it restricts itself to it's hypercall
>> namespace.
>> 
>
> I see.  So you take the fault, disassemble the instruction, see that its
> another CPU's vmcall instruction, and then replace it with the current
> CPU's vmcall?
> 

Yup.

>> Xen is currently using 0/1/2.  I had thought it was only using 0/1. 
>> The intention was not to squash Xen's current CPUID usage so that it
>> would still be possible for Xen to make use of the guest code.  Can we
>> agree that Xen won't squash leaves 3/4 or is it not worth trying to be
>> compatible at this point?
>> 
>
> No, the point is that you're supposed to work out which hypervisor it is
> from the signature in leaf 0, and then the hypervisor can put anything
> it wants in the other leaves.
> 

Yeah, see, the initial goal was to make it possible to use the KVM 
paravirtualizations on other hypervisors.  However, I don't think this 
is really going to be possible in general so maybe it's better to just 
use leaf 0.  I'll let others chime in before sending a new patch.

Regards,

Anthony Liguori

>     J
>
> 

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-09-14 23:49    [from the cache]
©2003-2008