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xen-ia64-devel
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
>
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