xen: x86_32: do not enable iterrupts when returning from exception in interrupt context
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):
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
CC: stable@kernel.org Signed-off-by: Igor Mammedov <imammedo@redhat.com> Signed-off-by: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>