Re: [PATCH] ns16550: MMIO r/o ranges are maintained at page granularity

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 30/08/2021 14:05, Jan Beulich wrote:
> Passing byte granular values will not have the intended effect. Address
> the immediate issue, but I don't think what we do is actually
> sufficient: At least some devices allow access to their registers via
> either I/O ports or MMIO. In such aliasing cases we'd need to protect
> the MMIO range even when we use I/O port accesses to drive the port.
>
> Note that this way we may write-protect MMIO ranges of unrelated devices
> as well. To deal with this, faults resulting from this would need
> handling, to emulate the accesses outside of the protected range. (An
> alternative would be to relocate the BAR, but I'm afraid this might end
> up even more challenging.)
>
> Fixes: c9f8e0aee507 ("ns16550: Add support for UART present in Broadcom TruManage 
> capable NetXtreme chips")
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>

Cheers,

--
Julien Grall