Re: [PATCH v6 0/4] memory: prevent dma-reentracy issues

[Darren Kenny <darren.kenny@oracle.com>]

Hi Alex,

Everything looks good to me, I don't have anything else to add:

Reviewed-by: Darren Kenny <darren.kenny@oracle.com>

Thanks,

Darren.

On Saturday, 2023-02-04 at 23:07:33 -05, Alexander Bulekov wrote:
> 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.
>
> v5 -> v6:
>     - Only apply checkpatch checks to code in paths containing "/hw/"
>       (/hw/ and include/hw/)
>     - Fix a bug in a _guarded call added to hw/block/virtio-blk.c
> 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/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 +
>  35 files changed, 147 insertions(+), 41 deletions(-)
>
> -- 
> 2.39.0