Re: [Xen-devel] Xen-4.3 - curious crash

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 29.01.14 at 09:51, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> On Wed, 2014-01-29 at 08:43 +0000, Jan Beulich wrote:
>> An interrupt not properly restoring EFLAGS.IF (or actually one not
>> properly restoring all of EFLAGS) would be very odd. About as odd
>> as a cosmic radiation induced bit flip resulting in some other
>> misbehavior.
> 
> Isn't it also the affect of a missing spin_unlock(_irqrestore)? Or does
> something else catch that first?

A missing plain spin_unlock() wouldn't have any effect of IF. And
a missing spin_unlock_irqrestore() would have an effect on IF in
the interrupt handler, but with the return being through an IRET
something would need to actively modify the flags on the stack
that IRET uses in order to affect the interrupted code's EFLAGS.

Jan


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