On 04/20/09 10:26, Avi Kivity wrote:
Gerd Hoffmann wrote:
The xen pv-on-hvm drivers use an msr to indicate "please place the
hypercall page here". Handling that in kernel isn't an option IMHO.
The contents of the hypercall page are vendor specific. This can be
handled from userspace (though ideally we'd abstract the cpu vendor
away).
Well, xenner doesn't do vmcalls, so the page isn't vendor specific. It
looks different for 32bit / 64bit guests though. And it actually can be
multiple pages (with one msr write per page). So the interface for
in-kernel handling would be more complex than "here is a hypercall page
for you".
> The Hyper-V hypercall page is more problematic, as it's specified to
> be an overlay; the page doesn't have to exist in guest RAM.
In userspace it should be easy to handle though as qemu can just create
a new memory slot, right?
cheers,
Gerd
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