arm: Guests can trigger a deadlock on Cortex-A77

ISSUE DESCRIPTION

Cortex-A77 cores (r0p0 and r1p0) are affected by erratum 1508412 where software, under certain circumstances, could deadlock a core due to the execution of either a load to device or non-cacheable memory, and either a store exclusive or register read of the Physical Address Register (PAR_EL1) in close proximity.

IMPACT

A (malicious) guest that doesn’t include the workaround for erratum 1508412 could deadlock the core. This will ultimately result to a deadlock of the system.

VULNERABLE SYSTEMS

Systems running all version of Xen are affected.
This bug is specific to Arm Cortex-A77 cores r0p0 and r1p0.