I recently upgrade a HP server from one used CPU socket (4 cores + HT = 8 cores) to 2 used CPU sockets (16 cores).
However, I'm only able to assign 8 cores to a VM. When setting 16 it defaults back to 8 in the "new VM wizard", and when changing it from an existing VM it displays a red warning: "More VCPUs than physical CPUs may lead to reducded VM performance". Clicking ok still defaults it to 8 cores instead of 16.
My xenhost (dom0) however does have 16 CPUs allocated and actually recognises them.
I'm wondering why I am unable to add more than 8 vCPUs to a machine.
Prior to doing the server upgrade I was able to allocate 8 vCPUs as well, so it can't be HT related.