Re: [Xen-devel] (XEN) traps.c:3071: GPF (0000): ffff82d0801d76b2 -> ffff82d080222806

[Stefan Bader <stefan.bader@xxxxxxxxxxxxx>]

On 03.11.2014 11:51, Andrew Cooper wrote:
> On 03/11/14 09:45, Stefan Bader wrote:
>> I see the message from the subject on my Intel box whenever a guest (iirc 
>> even
>> dom0) starts up. It is not fatal and everything seems ok. I am just curious
>> about what might trigger this. The addresses look to be inside the hypervisor
>> code. I was wondering whether there is a simple way to figure out what this
>> relates to (likely need to look at the objdump of the unstripped hv module).
>>
>> Or has someone already looked into this and knows what likely is the cause?
>>
>> -Stefan
> 
> Specifically, the message indicates <type of fault>: faulting address ->
> fixup address
> 
> It is probably a wrmsr, and a higher logging level will indicate this. 
> My gut feeling is that it is dom0 attempting to load microcode using the
> native method.
> 
> ~Andrew
> 

The faulting address in my case seems to be rdmsr_save (xen-4.4.1 base), the
fixup address somewhere unspecific in hvm.c (not sure whether that makes sense
coming from a dom0 startup). I will have to re-compile this with the gdprintk
enabled to see which MSR that was.

rdmsr_normal:
            /* Everyone can read the MSR space. */
            /* gdprintk(XENLOG_WARNING,"Domain attempted RDMSR %p.\n",
                        _p(regs->ecx));*/
            if ( rdmsr_safe(regs->ecx, msr_content) )
                goto fail;

Though likely related to the following WRMSRs following (the addresses differ
from the subject I wasn't sure from where exactly I took the others and these
are with 4.4.1 and directly after boot):

(XEN) traps.c:3071: GPF (0000): ffff82d08018ef10 -> ffff82d080222685
(XEN) traps.c:3071: GPF (0000): ffff82d08018ef10 -> ffff82d080222685
(XEN) traps.c:3071: GPF (0000): ffff82d08018ef10 -> ffff82d080222685
(XEN) traps.c:3071: GPF (0000): ffff82d08018ef10 -> ffff82d080222685
(XEN) traps.c:2514:d0 Domain attempted WRMSR 0000000000000610 from 0x004281c2001
a8168 to 0x004281c200148168.
(XEN) traps.c:2514:d0 Domain attempted WRMSR 0000000000000610 from 0x004281c2001
a8168 to 0x004281c2001a0168.
(XEN) traps.c:2514:d0 Domain attempted WRMSR 0000000000000610 from 0x004281c2001
a8168 to 0x004201c2001a8168.
(XEN) traps.c:3071: GPF (0000): ffff82d08018ef10 -> ffff82d080222685
(XEN) traps.c:2514:d0 Domain attempted WRMSR 00000000000001b2 from 0x00000000000
00000 to 0x0000000000009600.

The 0x1b2 seems to be thermal interrupt control. Cannot find the 0x610 right now
(need to refresh my docs)...

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