Re: [PATCH for-4.15 v5 2/3] xen/x86: iommu: Ignore IOMMU mapping requests when a domain is dying

[Jan Beulich <jbeulich@xxxxxxxx>]

On 26.02.2021 11:56, Julien Grall wrote:
> From: Julien Grall <jgrall@xxxxxxxxxx>
> 
> The new x86 IOMMU page-tables allocator will release the pages when
> relinquishing the domain resources. However, this is not sufficient
> when the domain is dying because nothing prevents page-table to be
> allocated.
> 
> As the domain is dying, it is not necessary to continue to modify the
> IOMMU page-tables as they are going to be destroyed soon.
> 
> At the moment, page-table allocates will only happen when iommu_map().
> So after this change there will be no more page-table allocation
> happening because we don't use superpage mappings yet when not sharing
> page tables.
> 
> In order to observe d->is_dying correctly, we need to rely on per-arch
> locking, so the check to ignore IOMMU mapping is added on the per-driver
> map_page() callback.
> 
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Does this also want a Fixes: tag (the same as patch 1)?

Jan