Re: [PATCH] hisi_acc_vfio_pci: Remove the deferred_reset logic

[Jason Gunthorpe <jgg@ziepe.ca>]

On Thu, Feb 29, 2024 at 09:11:52AM +0000, Shameer Kolothum wrote:
> The deferred_reset logic was added to vfio migration drivers to prevent
> a circular locking dependency with respect to mm_lock and state mutex.
> This is mainly because of the copy_to/from_user() functions(which takes
> mm_lock) invoked under state mutex. But for HiSilicon driver, the only
> place where we now hold the state mutex for copy_to_user is during the
> PRE_COPY IOCTL. So for pre_copy, release the lock as soon as we have
> updated the data and perform copy_to_user without state mutex. By this,
> we can get rid of the deferred_reset logic.
> 
> Link: https://lore.kernel.org/kvm/20240220132459.GM13330@nvidia.com/
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
> ---
>  .../vfio/pci/hisilicon/hisi_acc_vfio_pci.c    | 48 +++++--------------
>  .../vfio/pci/hisilicon/hisi_acc_vfio_pci.h    |  6 +--
>  2 files changed, 14 insertions(+), 40 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason