Avi Kivity wrote:
> Gerd Hoffmann wrote:
>>   Hi,
>>
>> I've just noticed that xenner doesn't work for 64bit xen guest kernels
>> on my new shiny barcelona box.  The VM crashes when trying to access the
>> lapic.  lapic setup is done before idt setup, register dump looks like
>> init state, thus it most likely is a triple fault resetting the vcpu.
>> Turning off npt fixes it.
>>
>> xenner maps the lapic to ffff820000000000 (64bit guests) or fe900000
>> (32bit guests).  32bit works fine even with npt enabled.
>>
>> host kernel is fedora 9 with kvm-69 modules.
>>
>> ideas anyone?
> 
> Turn on logging in lapic.c.  See if something turns up.

It doesn't come that far according to kvmtrace.

> If not, the page tables are probably set up incorrectly, but in a way
> that kvm doesn't notice.

Dunno.  Tried kvmtrace and got the results attached without and with
NTP.  Cutted down to the important sequence, starting with the apic MSR
read.  After the msr access there are some page faults (some page table
pages are allocated and used to map the apic, thus likely triggering
shadow pt updates).  Then the apic access (id register).

With npt kvm doesn't see the apic access at all.  Also the TDP_FAULT
line looks fishy to me.  The "virt = ... " isn't a (guest) virtual address.

btw: the iowrite to 0x00ea is console output.

ideas anyone?
  Gerd

-- 
http://kraxel.fedorapeople.org/xenner/