Works fine for me under Proxmox, Q35 + 2 CPUs (1 socket, 2 cores, type=host). I suggest you include a serial console log of the failed boot and a dmesg of the working one.
Note that if your VM has no graphics, you _must_ set the serial console at the boot loader prompt, or it will reboot after the entry point message. This is not specific to Q35 hardware though -- BIOS console redirection stops working once the OS boots. -Andrew
