Re: [PATCH v7 01/14] iommu: add preemption support to iommu_{un,}map()

["Durrant, Paul" <xadimgnik@gmail.com>]

On 05/07/2022 13:43, Jan Beulich wrote:
> From: Roger Pau Monné <roger.pau@citrix.com>
> 
> The loop in iommu_{,un}map() can be arbitrary large, and as such it
> needs to handle preemption.  Introduce a new flag that signals whether
> the function should do preemption checks, returning the number of pages
> that have been processed in case a need for preemption was actually
> found.
> 
> Note that the cleanup done in iommu_map() can now be incomplete if
> preemption has happened, and hence callers would need to take care of
> unmapping the whole range (ie: ranges already mapped by previously
> preempted calls).  So far none of the callers care about having those
> ranges unmapped, so error handling in arch_iommu_hwdom_init() can be
> kept as-is.
> 
> Note that iommu_legacy_{un,}map() are left without preemption handling:
> callers of those interfaces aren't going to modified to pass bigger
> chunks, and hence the functions won't be modified as they are legacy and
> uses should be replaced with iommu_{un,}map() instead if preemption is
> required.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Paul Durrant <paul@xen.org>