[...]

quoted

Btw, I heard from Tianyu from Intel, you said there was a x2apic bug
in kvm forum and the bug maybe in kvm, I guess I meet the same bug
when run a windows guest(server version of windows 7, 2008 or 2012) w/
x2apic enabled in guest and -machine q35,kernel_irqchip=spit -device
intel-iommu, intremap=on in the QEMU command line.

Does it happen when you are running less than 8 VCPUs (max APIC ID < 8)?
QEMU always enabled x2APIC support in IOMMU (EIME) even though it
doesn't work under some configurations.

I'm digging  into the bug currently. :）

Regards,
Wanpeng Li