On 08/19/2012 12:27 PM, Avi Kivity wrote:
On 08/17/2012 08:53 AM, Gerd Hoffmann wrote:
Hi,
It might be instruction emulator bug in KVM. Attached is the trace.
qemu-2047 [000] d..2 261.999076: kvm_entry: vcpu 0 qemu-2047 [000] ...1 261.999077: kvm_emulate_insn:f0000:6201:fb (real) qemu-2047 [000] d..2 261.999078: kvm_entry: vcpu 0 ##### CPU 3 buffer started #### qemu-2047 [003] ...1 411.367592: kvm_emulate_insn: 20000:26c:cb (prot16) qemu-2047 [003] ...1 411.367593: kvm_inj_exception: #GP (0x844) qemu-2047 [003] d..2 411.367594: kvm_entry: vcpu 0
This looks suspious. vcpu migration issue? Or just something missing in the trace?
Looks like tracing with a too-small buffer size. I generally trace using
trace-cmd record -e kvm -b 100000
and with fingers crossed.
The RET FAR instruction failure (which trace-cmd report decodes) is probably not the original failure.
In fact it is, we mis-emulated stack operations when SS.B=0 but the address size was 32-bits, and there are bits set in the top 16 bits of ESP.
Why ESP has bits set in the top 16 bits is another question. Is seabios polluting those bits?