Re: [PATCH v7 5/6] memory: Allow disabling re-entrancy checking per-MR

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

On Monday, 2023-03-13 at 04:24:16 -04, Alexander Bulekov wrote:
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>

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

> ---
>  include/exec/memory.h | 3 +++
>  softmmu/memory.c      | 2 +-
>  2 files changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/include/exec/memory.h b/include/exec/memory.h
> index 6fa0b071f0..5154b123d8 100644
> --- a/include/exec/memory.h
> +++ b/include/exec/memory.h
> @@ -791,6 +791,9 @@ struct MemoryRegion {
>      unsigned ioeventfd_nb;
>      MemoryRegionIoeventfd *ioeventfds;
>      RamDiscardManager *rdm; /* Only for RAM */
> +
> +    /* For devices designed to perform re-entrant IO into their own IO MRs */
> +    bool disable_reentrancy_guard;
>  };
>  
>  struct IOMMUMemoryRegion {
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index 57bf18a257..3018fa2edb 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -544,7 +544,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
>      }
>  
>      /* Do not allow more than one simultanous access to a device's IO Regions */
> -    if (mr->owner &&
> +    if (mr->owner && !mr->disable_reentrancy_guard &&
>          !mr->ram_device && !mr->ram && !mr->rom_device && !mr->readonly) {
>          dev = (DeviceState *) object_dynamic_cast(mr->owner, TYPE_DEVICE);
>          if (dev) {
> -- 
> 2.39.0