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

[Jeremy Fitzhardinge <jeremy@goop.org>]

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@redhat.com>
> Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org>

One nit, this should be acked-by or reviewed-by, not signed-off-by,
since the patch isn't passing through my hands.

    J