Re: [Xen-devel] 64 bit Intel HVM Weirdness - setjmp\longjump fp exception in Xen, not on real hardware or AMD HVM

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Well, what would you expect the changelog to say? It's fixed in the
xen-3.4-testing.hg repository by changeset 19697, which is a backport of
xen-unstable.hg:19953.

 -- Keir

On 01/11/2009 19:32, "Allan Graves" <allan.graves@xxxxxxxxxx> wrote:

> Keir -
> 
> Hmm... according to /sys/hypervisor/version, I'm running 3.4.0.
> 
> Is there a reasonable chance this is fixed in 3.4.1?  I haven't seen
> anything in the changelogs...
> 
> 
> Allan
> 
> 
> 
> Keir Fraser wrote:
>> What version of Xen are you using? This bug may be fixed in Xen 3.3.2 and
>> Xen 3.4.1.
>> 
>>  -- Keir
>> 
>> On 30/10/2009 01:23, "Allan Graves" <allan.graves@xxxxxxxxxx> wrote:
>> 
>>   
>>> (Please excuse double posting - I was told xen-users was not the right
>>> list, to put it on xen-devel, as it was not a technical support query,
>>> but an issue.)
>>> 
>>> 
>>> The following program will crash with a fp exception on an INTEL 64 bit
>>> HVM domU only:
>>> #include <setjmp.h>
>>> jmp_buf env; main() { if(setjmp(env)) return; longjmp(env, 1); }
>>> 
>>> 
>>> This can be seen using both Linux and Windows 64 bit Guests.
>>> 
>>> 
>>> My machine is a Core 2 Duo with both VT-D and VT-X extensions enabled.
>>> Unfortunately, this is blocking our usage of 64 bit HVM Windows guests.
>>> 
>>> A similar issue was reported in KVM and recently fixed, some of their
>>> analysis is below:
>>> --------------------------------------------------
>>>     
>>>>>> It seems that the problem can be reproduced by compiling the
>>>>>> following simple program using cygwin's gcc. The program crashes on
>>>>>> w2k3-amd64 on kvm-83 on core2-duo, and it does not crash on the
>>>>>> same w2k3-amd64 installation on kvm-83 on AMD Phenom.
>>>>>> 
>>>>>> #include <setjmp.h>
>>>>>> 
>>>>>> jmp_buf env; main() { if(setjmp(env)) return; longjmp(env, 1); }
>>>>>> 
>>>>>> The problem seems to be in the instruction ``mov gs,ax'' (Intel
>>>>>> syntax) in the longjmp() code. If I let the virtual machine execute
>>>>>> the instruction, the program crashes. However, if I step over the
>>>>>> instruction using the vs2008 debugger, the program completes
>>>>>> without crashing. Thus, I think that this is the instruction that
>>>>>> Avi is looking for, but I don't know how to proceed from here.
>>>>>> -------------------------------------------------------
>>>>>>           
>>> http://markmail.org/message/owy3x7pf6oywdx5e#query:+page:1+mid:spz6vmdothb2n
>>> jf
>>> b+state:results
>>> 
>>> 
>>> 
>>> Anyone have a solution to this? :)
>>> 
>>> Allan
>>> 
>>> 
>>> 
>>> 
>>> 
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>>> http://lists.xensource.com/xen-devel
>>>     
>> 
>> 
>>   



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