[PATCH v5 0/4] memory: prevent dma-reentracy issues

[Alexander Bulekov]

These patches aim to solve two types of DMA-reentrancy issues:

1.) mmio -> dma -> mmio case
To solve this, we track whether the device is engaged in io by
checking/setting a reentrancy-guard within APIs used for MMIO access.

2.) bh -> dma write -> mmio case
This case is trickier, since we dont have a generic way to associate a
bh with the underlying Device/DeviceState. Thus, this version allows a
device to associate a reentrancy-guard with a bh, when creating it.
(Instead of calling qemu_bh_new, you call qemu_bh_new_guarded)

I replaced most of the qemu_bh_new invocations with the guarded analog,
except for the ones where the DeviceState was not trivially accessible

v4-> v5: 
    - Add corresponding checkpatch checks
    - Save/restore reentrancy-flag when entering/exiting BHs
    - Improve documentation
    - Check object_dynamic_cast return value

v3 -> v4: Instead of changing all of the DMA APIs, instead add an
    optional reentrancy guard to the BH API.

v2 -> v3: Bite the bullet and modify the DMA APIs, rather than
    attempting to guess DeviceStates in BHs.

Alexander Bulekov (4):
  memory: prevent dma-reentracy issues
  async: Add an optional reentrancy guard to the BH API
  checkpatch: add qemu_bh_new/aio_bh_new checks
  hw: replace most qemu_bh_new calls with qemu_bh_new_guarded

 docs/devel/multiple-iothreads.txt |  7 +++++++
 hw/9pfs/xen-9p-backend.c          |  4 +++-
 hw/block/dataplane/virtio-blk.c   |  3 ++-
 hw/block/dataplane/xen-block.c    |  5 +++--
 hw/block/virtio-blk.c             |  5 +++--
 hw/char/virtio-serial-bus.c       |  3 ++-
 hw/display/qxl.c                  |  9 ++++++---
 hw/display/virtio-gpu.c           |  6 ++++--
 hw/ide/ahci.c                     |  3 ++-
 hw/ide/core.c                     |  3 ++-
 hw/misc/imx_rngc.c                |  6 ++++--
 hw/misc/macio/mac_dbdma.c         |  2 +-
 hw/net/virtio-net.c               |  3 ++-
 hw/nvme/ctrl.c                    |  6 ++++--
 hw/scsi/mptsas.c                  |  3 ++-
 hw/scsi/scsi-bus.c                |  3 ++-
 hw/scsi/vmw_pvscsi.c              |  3 ++-
 hw/usb/dev-uas.c                  |  3 ++-
 hw/usb/hcd-dwc2.c                 |  3 ++-
 hw/usb/hcd-ehci.c                 |  3 ++-
 hw/usb/hcd-uhci.c                 |  2 +-
 hw/usb/host-libusb.c              |  6 ++++--
 hw/usb/redirect.c                 |  6 ++++--
 hw/usb/xen-usb.c                  |  3 ++-
 hw/virtio/virtio-balloon.c        |  5 +++--
 hw/virtio/virtio-crypto.c         |  3 ++-
 include/block/aio.h               | 18 ++++++++++++++++--
 include/hw/qdev-core.h            |  7 +++++++
 include/qemu/main-loop.h          |  7 +++++--
 scripts/checkpatch.pl             |  8 ++++++++
 softmmu/memory.c                  | 17 +++++++++++++++++
 softmmu/trace-events              |  1 +
 tests/unit/ptimer-test-stubs.c    |  3 ++-
 util/async.c                      | 18 +++++++++++++++++-
 util/main-loop.c                  |  5 +++--
 util/trace-events                 |  1 +
 36 files changed, 150 insertions(+), 43 deletions(-)

-- 
2.39.0