On Tuesday, 2023-05-16 at 04:40:02 -04, Alexander Bulekov wrote:
> engaged_in_io could be unset by an MR with re-entrancy checks disabled.
> Ensure that only MRs that can set the engaged_in_io flag can unset it.
>
> Closes: https://gitlab.com/qemu-project/qemu/-/issues/1563
> Reported-by: Thomas Huth <thuth@redhat.com>
> Signed-off-by: Alexander Bulekov <alxndr@bu.edu>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
> ---
> softmmu/memory.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index b7b3386e9d..26424f1d78 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -534,6 +534,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
> unsigned access_size;
> unsigned i;
> MemTxResult r = MEMTX_OK;
> + bool reentrancy_guard_applied = false;
>
> if (!access_size_min) {
> access_size_min = 1;
> @@ -552,6 +553,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
> return MEMTX_ACCESS_ERROR;
> }
> mr->dev->mem_reentrancy_guard.engaged_in_io = true;
> + reentrancy_guard_applied = true;
> }
>
> /* FIXME: support unaligned access? */
> @@ -568,7 +570,7 @@ static MemTxResult access_with_adjusted_size(hwaddr addr,
> access_mask, attrs);
> }
> }
> - if (mr->dev) {
> + if (mr->dev && reentrancy_guard_applied) {
> mr->dev->mem_reentrancy_guard.engaged_in_io = false;
> }
> return r;
> --
> 2.39.0