Re: Xen HVM regression on certain Intel CPUs

[Keir Fraser <keir.xen@gmail.com>]

On 03/04/2013 13:43, "Jan Beulich" <JBeulich@suse.com> wrote:

>>>> On 03.04.13 at 13:56, Stefan Bader <stefan.bader@canonical.com> wrote:
>> I added some more debugging output to the hypervisor to verify the state of
>> HAP.
>> This showed that while HAP is available on the system, it is not used for the
>> HVM guests. It looks like this would require some flags to be set when
>> creating
>> the guest domains and I assume this is not happening because I have to stay
>> with
>> the xm stack for the libvirt setup for now (requires some repackaging which
>> hasn't been done, yet).
>> 
>> So the guest isn't using HAP but does seem to use some form of paging even if
>> the guest VCPU is not using paging. So I changed the vmx_update_guest_cr()
>> function in that way and that seems to prevent the hangs. Does this look like
>> a
>> reasonable upstream Xen change?
> 
> Yes, it looks appropriate. But I'd like this to be confirmed by the
> authors of the original change and/or the VMX maintainers (added
> to Cc).

It can have my ack straight away.

Acked-by: Keir Fraser <keir@xen.org>

Nonetheless it would be nice to get a VMX maintainer ack too, though I'm
pretty sure this patch is correct.

 -- Keir

> Nevertheless it's very odd to not use HAP on a machine capable
> of it...
> 
> Jan
> 
> 
> 
> 
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