lkml.org 
[lkml]   [2007]   [Sep]   [15]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateSat, 15 Sep 2007 12:33:41 -0500
FromAnthony Liguori <>
SubjectRe: [kvm-devel] [PATCH] Refactor hypercall infrastructure
Zachary Amsden wrote:
> On Fri, 2007-09-14 at 16:44 -0500, Anthony Liguori wrote:
>
> 
>> So then each module creates a hypercall page using this magic MSR and 
>> the hypervisor has to keep track of it so that it can appropriately 
>> change the page on migration.  The page can only contain a single 
>> instruction or else it cannot be easily changed (or you have to be able 
>> to prevent the guest from being migrated while in the hypercall page).
>>
>> We're really talking about identical models.  Instead of an MSR, the #GP 
>> is what tells the hypervisor to update the instruction.  The nice thing 
>> about this is that you don't have to keep track of all the current 
>> hypercall page locations in the hypervisor.
>> 
>
> I agree, multiple hypercall pages is insane.  I was thinking more of a
> single hypercall page, fixed in place by the hypervisor, not the kernel.
>
> Then each module can read an MSR saying what VA the hypercall page is
> at, and the hypervisor can simply flip one page to switch architectures.
> 

That requires a memory hole though.  In KVM, we don't have a memory hole.

Regards,

Anthony Liguori

> Zach
>
> 

-
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: 2007-09-15 19:37    [from the cache]
©2003-2008