[Qemu-devel] [PATCH v4 0/3] pci: implement upstream master abort protocol

[Marcel Apfelbaum <marcel.a@redhat.com>]

PCI spec requires that a transaction that has not been claimed
by any PCI bus devices will be terminated by the initiator
with "master abort". For read transactions -1(FFFFFFFF) is returned and 
writes are silently dropped.

Implementation:
 - Allowed the MemoryRegion priority to be negative so a subregion will be
   visible on all the addresses not covered by other container subregions.
 - Added a memory region with negative priority that extends over all the
   pci address space. This region catches all the accesses
   to the unassigned pci addresses.
 - The MemoryRegion's ops emulates the master abort scenario.

Note: The code handles only the reads/writes to pci address space
that are done by the cpu.

I am working on implementing the following on top of this series
 - Implement upstream master abort
 - Handling of RECEIVED MASTER ABORT BIT in Stastus register

Changes from v3:
 - Addressed Peter Maydell comments
   - Removed unnecessary changes to priority of MemoryListener
   - Ensured that priority is now signed in all related places
   - Added to memory docs explanation on signed priorities
 - Addresses Michael S. Tsirkin comments
   - Changed the name of the new Memory region to master_abort_mem
   - Made master abort priority INT_MIN instead of -1
 - Removed handling of RECEIVED MASTER ABORT BIT; it will be taken
   care in a different series

Changes from v2:
 - minor: changed nr of patches in the title
 - minor: modified series list

Changes from v1:
 - "pci-unassigned-mem" MemoryRegion resides now in PCIBus and not on
    various Host Bridges
 - "pci-unassgined-mem" does not have a ".valid.accept" field and
    implements read write methods


Marcel Apfelbaum (3):
  memory: allow MemoryRegion's priority field to accept negative values
  docs/memory: Explictly state that MemoryRegion priority is signed
  hw/pci: partially handle pci master abort

 docs/memory.txt          |  4 ++++
 hw/core/sysbus.c         |  4 ++--
 hw/pci/pci.c             | 27 +++++++++++++++++++++++++++
 include/exec/memory.h    |  4 ++--
 include/hw/pci/pci_bus.h |  1 +
 include/hw/sysbus.h      |  2 +-
 memory.c                 |  4 ++--
 7 files changed, 39 insertions(+), 7 deletions(-)

-- 
1.8.3.1