On 04/20/09 13:27, Avi Kivity wrote:
Gerd Hoffmann wrote:
Well, xenner doesn't do vmcalls, so the page isn't vendor specific.
Well, for true pv (not pv-on-hvm) it wouldn't use the MSR, would it?
Yes, the MSR is used for pv-on-hvm only.
So it isn't relevant for Xenner?
It is. I still plan to merge xenner into qemu, and also support
xenstyle pv-on-hvm drivers.
That said, I'd like to be able to emulate the Xen HVM hypercalls. But in
any case, they hypercall implementation has to be in the kernel,
No. With Xenner the xen hypercall emulation code lives in guest address
space.
so I
don't see why the MSR shouldn't be.
I don't care that much, but /me thinks it would be easier to handle in
userspace ...
Especially if we need to support
tricky bits like continuations.
Is there any reason to? I *think* xen does it for better scheduling
latency. But with xen emulation sitting in guest address space we can
schedule the guest at will anyway.
Same MSR, multiple writes (page number in the low bits).
Nasty. The hypervisor has to remember all of the pages, so it can update
them for live migration.
Xenner doesn't need update-on-migration, so there is no need at all to
remember this. At the end of the day it is just memcpy(guest, data,
PAGESIZE) triggered by wrmsr.
cheers,
Gerd
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