Only one CPU core detected when booting on UEFI

[Xiao-Long Chen <chenxiaolong@cxl.epac.to>]

Hi Xen developers,

I have been having a problem where only one CPU core is being detected.
I'm using a Lenovo W520 with a UEFI firmware and an Intel Core i7
2720qm (4 real cores, 4 virtual cores). When I boot, I see
"Dom0 has maximum 1 VCPUs", or something similar, scroll by.

In addition, only 10 GB out of my 12 GB of memory is recognized and
ACPI is not working properly (CPU frequency scaling and battery info
are not reported).

This problem has been reported before (for the same laptop too) here:
http://lists.xen.org/archives/html/xen-devel/2012-06/msg00087.html but
unfortunately, the person who sent the message didn't reply with more
information.

Here are the outputs of dmesg with and without Xen:

Without Xen: http://paste.kde.org/626222/raw/
With Xen: http://paste.kde.org/626228/raw/

and some information from xl:

xl vcpu-list: http://paste.kde.org/626234/raw/
xl info: http://paste.kde.org/626240/raw/
xl dmesg: http://paste.kde.org/626246/raw/

This is my first time venturing into Xen territory, so please let me
know if there's any other information needed.

I'm not sure if it helps, but I'd also like to point out that I had a
similar problem with Linux back around July 20, 2011, when I got my
computer. I could work around the issue by booting with "noapic". I'm
not sure which kernel version fixed the issue as I booted with that
option for quite a while. The kernel version, at the time, was 3.0.

I am glad to help in any way I can. I'm excited to get Xen working!
I'm confortable with compiling the kernel or xen if necessary.

Thanks in advance!

Xiao-Long Chen