RE: [Xen-ia64-devel] [PATCH] About fault handle in nested interrupt

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

OK, though an extra page fault happens, it looks clearer.

Thanks,
Kevin

>-----Original Message-----
>From: Magenheimer, Dan (HP Labs Fort Collins) [mailto:dan.magenheimer@xxxxxx]
>Sent: 2005年11月29日 7:47
>To: Tian, Kevin; xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>Subject: RE: [Xen-ia64-devel] [PATCH] About fault handle in nested interrupt
>
>Agreed, faults in Xen should never be reflected to a
>guest, so this is a bug.  Should we use BUG_ON or
>panic, instead of panic_domain?
>
>> -----Original Message-----
>> From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>> [mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf
>> Of Tian, Kevin
>> Sent: Wednesday, November 23, 2005 11:19 PM
>> To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>> Subject: [Xen-ia64-devel] [PATCH] About fault handle in
>> nested interrupt
>>
>> Hi, Dan,
>>      When looking at the unaligned issue raised by Kanno, I think
>> there's an issue to handle nested fault happened in the hypervisor.
>>
>>      Take above unaligned fault for example. One bogus structure is
>> allocated unaligned, and then Xen tries to access that unaligned
>> structure. Unaligned fault happens within Xen, and finally
>> flow goes to
>> ia64_handle_reflection. There's a check upon ipsr.cpl to see whether
>> fault from Xen itself. If true, only a warning is printed out and
>> subsequent lines will still be executed just as fault from guest.
>> Finally reflect_interruption is called and pt_regs.iip is changed to
>> unaligned offset within guest IVT table.
>>
>>      Actually you can see from this flow that everything will get
>> messed after fault is injected into guest, since incorrect register
>> contents of Xen are recovered to guest. This will bring developer much
>> confusion about when/where things go wrong exactly, since more faults
>> will be raised due to above incorrect injection.
>>
>>      Normally the faults reflected back to guest directly shouldn't
>> happen within Xen, or else that means a bug and we need panic and dump
>> the stack at that point immediately. This can make people easier to
>> track bugs. ;-)
>>
>> Signed-off-by Kevin Tian <Kevin.tian@xxxxxxxxx>
>>
>> Thanks,
>> Kevin
>>

_______________________________________________
Xen-ia64-devel mailing list
Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-ia64-devel