CentOS virt - May 2008 - xen kernel showing only one processor on SMP machine

Hi there,

I'm running an ibm xseries 345/dual Xeon 2.66GHz, 2.6.18-53.1.14.el5xen 
#1 SMP, and cat /proc/cpuinfo shows me only one processor. Apparently 
something strange happening with ACPI. What am I doing wrong? Thank you!
(sorry for the cross post, didn't realize there was a virt list first 
time around!)

Selected bits from dmesg:
-------------------------
Using ACPI (MADT) for SMP configuration information
SMP alternatives: switching to UP code
ACPI: Core revision 20060707
CPU 1 irqstacks, hard=c0728000 soft=c0708000
CPU 2 irqstacks, hard=c0729000 soft=c0709000
CPU 3 irqstacks, hard=c072a000 soft=c070a000
ENABLING IO-APIC IRQs
SMP alternatives: switching to SMP code
Initializing CPU#1
Initializing CPU#2
Brought up 4 CPUs

ACPI Exception (acpi_processor-0681): AE_NOT_FOUND, Processor Device is 
not present [20060707]
ACPI: Getting cpuindex for acpiid 0x3
ACPI Exception (acpi_processor-0681): AE_NOT_FOUND, Processor Device is 
not present [20060707]
ACPI: Getting cpuindex for acpiid 0x1