Re: [PATCH v3] arm/ioreq: guard interaction data on read/write operations

[Julien Grall <julien@xxxxxxx>]

Hi Andrii,

On 05/10/2023 14:30, Andrii Chepurnyi wrote:
> For read operations, there's a potential issue when the data field
> of the ioreq struct is partially updated in the response. To address
> this, zero data field during read operations. This modification
> serves as a safeguard against implementations that may inadvertently
> partially update the data field in response to read requests.
> For instance, consider an 8-bit read operation. In such cases, QEMU,
> returns the same content of the data field with only 8 bits of
> updated data. This behavior could potentially result in the
> propagation of incorrect or unintended data to ioreq clients.
> During a write access, the Device Model only need to know the content
> of the bits associated with the access size (e.g. for 8-bit, the lower
> 8-bits). During a read access, the Device Model don't need to know any
> value. So restrict the value it can access.
>
> Signed-off-by: Andrii Chepurnyi <andrii_chepurnyi@xxxxxxxx>
Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Unless there are any objections, I will commit the patch tomorrow (Friday).

Cheers,

--
Julien Grall