[Qemu-devel] [PATCH 0/4] target-ppc/spapr: Add FWNMI support in QEMU for PowerKVM guests

[Aravinda Prasad <aravinda@linux.vnet.ibm.com>]

This series of patches add support for FWNMI in PowerKVM guests.

Memory error such as bit flips that cannot be corrected
by hardware is passed on to the kernel for handling
by raising machine check exception (an NMI). Upon such
machine check exception, if the address in error belongs
to guest then KVM causes a guest exit with KVM_EXIT_NMI
exit reason [1].

This patch series adds functionality to pass on such
machine check exception to the guest kernel by suitably
handling KVM_EXIT_NMI exit and building the error log.
This patch series explores the alternate design
discussed in the QEMU mailing list [2], [3].

In earlier design [2] KVM invoked guest's NMI interrupt
vector 0x200 upon machine check exception, while QEMU
patched 0x200 vector to issue hcall to facilitate
building and copying of error log into RTAS space.

The new design simplifies couple of things. Thanks to
David Gibson for the suggestion:

    - Eliminates patching of 0x200 interrupt vector from
      QEMU, hence, trampoline not required
    - Avoids introducing a new private hcall to be called
      from guest's 0x200 vector to enable QEMU to build
      error log
    - Simplifies re-trying by other processors when one
      of the processor is consuming/processing the error
      log.

[1] http://marc.info/?l=kvm-ppc&m=144726114408289
[2] https://lists.nongnu.org/archive/html/qemu-devel/2014-11/msg00813.html
[3] https://lists.nongnu.org/archive/html/qemu-devel/2015-08/msg00898.html

---

Aravinda Prasad (4):
      spapr: Extend rtas-blob
      spapr: Register and handle HCALL to receive updated RTAS region
      spapr: Handle "ibm,nmi-register" and "ibm,nmi-interlock" RTAS calls
      target-ppc: Handle NMI guest exit


 hw/ppc/spapr.c         |    4 ++
 hw/ppc/spapr_hcall.c   |    8 +++++
 hw/ppc/spapr_rtas.c    |   29 +++++++++++++++++
 include/hw/ppc/spapr.h |   11 +++++--
 target-ppc/kvm.c       |   69 +++++++++++++++++++++++++++++++++++++++++
 target-ppc/kvm_ppc.h   |   81 ++++++++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 200 insertions(+), 2 deletions(-)

-- 
Aravinda Prasad