Re: [PATCH v3 1/7] memory: associate DMA accesses with the initiator Device

[Peter Xu]

On Fri, Oct 28, 2022 at 03:16:42PM -0400, Alexander Bulekov wrote:
> +    /* Do not allow more than one simultanous access to a device's IO 
> Regions */
> +    if (mr->owner &&
> +            !mr->ram_device && !mr->ram && !mr->rom_device && !mr->readonly) 
> {
> +        dev = (DeviceState *) object_dynamic_cast(mr->owner, TYPE_DEVICE);
> +        if (dev->mem_reentrancy_guard.engaged_in_io) {

Do we need to check dev being non-NULL?  Fundamentally it's about whether
the owner can be not a DeviceState, I believe it's normally true but I
can't tell; at least from memory region API it can be any Object*.

> +            trace_memory_region_reentrant_io(get_cpu_index(), mr, addr, 
> size);
> +            return MEMTX_ERROR;
> +        }
> +        dev->mem_reentrancy_guard.engaged_in_io = true;
> +    }

-- 
Peter Xu