[Qemu-devel] [PATCH RFC v2 0/3] 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 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
  hw/pci: add MemoryRegion ops for unassigned pci addresses
  hw/pci-host: catch acesses to unassigned pci addresses

 hw/pci-host/piix.c        |  8 ++++++++
 hw/pci-host/q35.c         | 19 ++++++++++++++++---
 hw/pci/pci.c              | 18 ++++++++++++++++++
 include/exec/memory.h     |  6 +++---
 include/hw/pci-host/q35.h |  1 +
 include/hw/pci/pci.h      |  3 +++
 memory.c                  |  2 +-
 7 files changed, 50 insertions(+), 7 deletions(-)

-- 
1.8.3.1