Re: [Qemu-devel] E5-2620v2 - emulation stop error

Radim Krčmář
2015-03-26T15:58:12Z

2015-03-25 20:05-0400, Kevin O'Connor:
> On Thu, Mar 26, 2015 at 02:35:58AM +0300, Andrey Korolyov wrote:
> > Thanks, strangely the reboot is always failing now and always reaching
> > seabios greeting. May be prints straightened up a race (e.g. it is not
> > int19 problem really).
> >
> > object file part:
> >
> > 0000d331 <irq_trampoline_0x19>:
> > irq_trampoline_0x19():
> > /root/seabios-1.8.1/src/romlayout.S:195
> > d331: cd 19 int $0x19
> > d333: cb lretw
>
> [...]
> > Jump to int19 (vector=f000e6f2)
>
> Thanks. So, it dies on the "int $0x19" instruction itself. The
> vector looks correct and I don't see anything in the cpu register
> state that looks wrong. Maybe one of the kvm developers will have an
> idea what could cause a fault there.

The place agrees with the "<cd> 19 cb" part of KVM error output.
Suberror 2 means that we were interrupted while delivering a vector,
here it is disected: (delivering 'vect_info')

vect_info (extra data[0]: 800000ef)
- vector 0xef
- INTR_TYPE_EXT_INTR (0x000)
- no error code (0x000)
- valid (0x80000000)

intr_info (extra data[1]: 80000b0d)
- #GP (0x0d)
- INTR_TYPE_HARD_EXCEPTION (0x300)
- error code on stack (0x800) [Hunk at the bottom exposes it.]
- valid (0x80000000)

Notice the 0xef. My best hypothesis so far is that we fail at resetting
devices, and 0xef is LOCAL_TIMER_VECTOR from Linux before we rebooted.
(The bug happens at the first place that enables interrupts.)

This should be handled without an internal error, though.
(It's possible we are hitting two bugs here ...)

Can you provide KVM event trace as well? (`trace-cmd record -e 'kvm*'`)

Thanks.

---
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 50c675b46901..541a29476a56 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5088,9 +5088,10 @@ static int handle_exception(struct kvm_vcpu *vcpu)
!(is_page_fault(intr_info) && !(error_code & PFERR_RSVD_MASK))) {
vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_SIMUL_EX;
- vcpu->run->internal.ndata = 2;
+ vcpu->run->internal.ndata = 3;
vcpu->run->internal.data[0] = vect_info;
vcpu->run->internal.data[1] = intr_info;
+ vcpu->run->internal.data[2] = error_code;
return 0;
}