Re: xen-unstable fails to boot on a system with Ivy Bridge stepping C0 cpu

[Igor Mammedov <imammedo@redhat.com>]

On 11/03/2011 02:10 PM, Tim Deegan wrote:
> At 13:44 +0100 on 03 Nov (1320327869), Igor Mammedov wrote:
>> Hi,
>>
>> I need a help with tracking down following issue:
>>
>> When trying to boot Xen on a system with Ivy Bridge stepping C0 CPU, it is
>> stuck on CPU initialization.
>> I've added some tracing to apic writes/reads and traced it so far to
>> sending INIT IPI.
>>
>> (XEN) HVM: VMX enabled
>> (XEN) HVM: Hardware Assisted Paging detected.
>> (XEN) Setting warm reset code and vector.
>> (XEN) apic_wrmsr (0x280,0x0)
>> (XEN) apic_rdmsr(0x280) = 0x0
>> (XEN) Asserting INIT.
>> (XEN) apic_wrmsr (0x300,0x10000c500)
>>
>> After this ^^^^ write BSP becomes VERY slow and it takes several minutes
>> till it gets to sending STARTUP IPI:
>
> Does reverting 23724:b3434f24b082 help?  Looking at it again I'm not
                  ^^^^^
reverting this c/s won't help, because the same problem exists in older xen
versions 3.x.x that doesn't have this c/s.
Actually I've tried rhel5, suse 4.1 and xen-unstable so far, all of them are
affected.

If we put printk right after sending INIT|ASSERT IPI it will show that BSP
is slowed down by printing 1 character in a several seconds. So deassert
probably is not of an issue here, since this happens on the first INIT to
the first AP.


> sure that the new logic is entirely correct - in particular it no longer
> deasserts the INIT on x2apic systems.
>
> Cheers,
>
> Tim.
>

-- 
Thanks,
  Igor