[Qemu-devel] [PATCH RFC v3 0/2] pci: complete master abort protocol

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

Note: The series is incomplete, for review only

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.

The series deals also with the other aspect of the master abort scenario:
Upon completion the master has to raise RECEIVED MASTER ABORT BIT in
initiator's STATUS register.

Implementation:
 - Allowed the MemoryRegion priority to be negative so a subregion will be
   visible on all the addresses not covered by the parent MemoryRegion
   or other 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:
For the moment the code assumes that all the reads/writes to
pci address space are done by the cpu.

Changes from v2:
 - minor: changed nr of patches int 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 (2):
  memory: allow MemoryRegion's priority field to accept negative values
  hw/pci: handle unassigned pci addresses

 hw/pci/pci.c             | 46 ++++++++++++++++++++++++++++++++++++++++++++++
 include/exec/memory.h    |  6 +++---
 include/hw/pci/pci_bus.h |  1 +
 memory.c                 |  2 +-
 4 files changed, 51 insertions(+), 4 deletions(-)

-- 
1.8.3.1