Re: [PATCH v2 22/24] iommu: Allow enabling non-strict mode dynamically

John Garry
2021-07-30T09:27:03Z

On 28/07/2021 16:58, Robin Murphy wrote:
> Allocating and enabling a flush queue is in fact something we can
> reasonably do while a DMA domain is active, without having to rebuild it
> from scratch. Thus we can allow a strict -> non-strict transition from
> sysfs without requiring to unbind the device's driver, which is of
> particular interest to users who want to make selective relaxations to
> critical devices like the one serving their root filesystem.
>
> Disabling and draining a queue also seems technically possible to
> achieve without rebuilding the whole domain, but would certainly be more
> involved. Furthermore there's not such a clear use-case for tightening
> up security*after* the device may already have done whatever it is that
> you don't trust it not to do, so we only consider the relaxation case.
>
> Signed-off-by: Robin Murphy<robin.murphy@arm.com>

Reviewed-by: John Garry <john.garry@huawei.com>