[Xen-devel] Re: [PATCH v2] xen: x86_32: do not enable iterrupts when returning from exception in interrupt context

[Igor Mammedov <imammedo@xxxxxxxxxx>]

On 09/01/2011 06:46 PM, Jeremy Fitzhardinge wrote:
> On 09/01/2011 04:46 AM, Igor Mammedov wrote:
> > If vmalloc page_fault happens inside of interrupt handler with interrupts
> > disabled then on exit path from exception handler when there is no pending
> > interrupts, the following code (arch/x86/xen/xen-asm_32.S:112):
> >
> >         cmpw $0x0001, XEN_vcpu_info_pending(%eax)
> >         sete XEN_vcpu_info_mask(%eax)
> >
> > will enable interrupts even if they has been previously disabled according to
> > eflags from the bounce frame (arch/x86/xen/xen-asm_32.S:99)
> >
> >         testb $X86_EFLAGS_IF>>8, 8+1+ESP_OFFSET(%esp)
> >         setz XEN_vcpu_info_mask(%eax)
> >
> > Solution is in setting XEN_vcpu_info_mask only when it should be set
> > according to
> >         cmpw $0x0001, XEN_vcpu_info_pending(%eax)
> > but not clearing it if there isn't any pending events.
> >
> > Reproducer for bug is attached to RHBZ 707552
> >
> > Signed-off-by: Igor Mammedov<imammedo@xxxxxxxxxx>
> > Signed-off-by: Jeremy Fitzhardinge<jeremy@xxxxxxxx>
> One nit, this should be acked-by or reviewed-by, not signed-off-by,
> since the patch isn't passing through my hands.
>
>      J
I'm new to this stuff, would you like me to re-post it?
Next time will do it right.

-------
Thanks,
   Igor

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