[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Xen-devel] Can't boot as Xen dom0 due to commit fe055896



On 15/12/16 17:46, Borislav Petkov wrote:
> On Thu, Dec 15, 2016 at 05:12:04PM +0100, Juergen Gross wrote:
>> with today's kernel the system isn't coming up when booted as Xen dom0:
> 
> Remind me again pls, is dom0 even supposed to load microcode? Isn't the
> hypervisor supposed to apply microcode?
> 
>> Looking into the state of cpu 1 I find the following backtrace (created
>> manually by looking up addresses from a stack dump retrieved from the
>> hypervisor):
>>
>> find_cpio_data()
>> find_microcode_in_initrd()
>> __load_ucode_intel()
>> load_ucode_intel_ap()
>> cpu_init()
>> cpu_bringup()
>> cpu_bringup_and_idle()
>>
>> It seems as if load_ucode_intel_ap() is looping. You introduced a
>> possibly endless loop in it with commit fe055896.
> 
> Are you sure you mean:
> 
>   fe055896c040 ("x86/microcode: Merge the early microcode loader")
> 
> because that commit is a year old.

OMG. Sorry, somehow I managed to read the date of that patch wrong.

> So from looking at the *current* code:
> 
>       if (apply_microcode_early(&uci, true)) {
> 
> fails probably because MSR_IA32_UCODE_REV doesn't get read properly due
> to virtualized MSRs, bla, yadda yadda...

I'll check.

BTW: Adding a retry count doesn't help. Just tried.

> But before we debug this further, I'd like to make sure I'm debugging
> the proper thing and not some situation again where xen wasn't even
> supposed to run the microcode loader but it does it anyway...

I guess this might be the case.


Juergen


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel

 


Rackspace

Lists.xenproject.org is hosted with RackSpace, monitoring our
servers 24x7x365 and backed by RackSpace's Fanatical Support®.