1. 14 Oct, 2017 1 commit
    • Paul Mackerras's avatar
      KVM: PPC: Book3S HV: Handle unexpected interrupts better · 857b99e1
      Paul Mackerras authored
      At present, if an interrupt (i.e. an exception or trap) occurs in the
      code where KVM is switching the MMU to or from guest context, we jump
      to kvmppc_bad_host_intr, where we simply spin with interrupts disabled.
      In this situation, it is hard to debug what happened because we get no
      indication as to which interrupt occurred or where.  Typically we get
      a cascade of stall and soft lockup warnings from other CPUs.
      
      In order to get more information for debugging, this adds code to
      create a stack frame on the emergency stack and save register values
      to it.  We start half-way down the emergency stack in order to give
      ourselves some chance of being able to do a stack trace on secondary
      threads that are already on the emergency stack.
      
      On POWER7 or POWER8, we then just spin, as before, because we don't
      know what state the MMU context is in or what other threads are doing,
      and we can't switch back to host context without coordinating with
      other threads.  On POWER9 we can do better; there we load up the host
      MMU context and jump to C code, which prints an oops message to the
      console and panics.
      Signed-off-by: default avatarPaul Mackerras <paulus@ozlabs.org>
      857b99e1
  2. 12 Oct, 2017 39 commits