Re: [PATCH v2 1/1] s390/pv: fix the forcing of the swiotlb

Konrad Rzeszutek Wilk
2021-07-24T00:28:02Z

On Sat, Jul 24, 2021 at 01:17:46AM +0200, Halil Pasic wrote:
> Since commit 903cd0f315fe ("swiotlb: Use is_swiotlb_force_bounce for
> swiotlb data bouncing") if code sets swiotlb_force it needs to do so
> before the swiotlb is initialised. Otherwise
> io_tlb_default_mem->force_bounce will not get set to true, and devices
> that use (the default) swiotlb will not bounce despite switolb_force
> having the value of SWIOTLB_FORCE.
>
> Let us restore swiotlb functionality for PV by fulfilling this new
> requirement.
>
> This change addresses what turned out to be a fragility in
> commit 64e1f0c531d1 ("s390/mm: force swiotlb for protected
> virtualization"), which ain't exactly broken in its original context,
> but could give us some more headache if people backport the broken
> change and forget this fix.
>
> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>
> Fixes: 903cd0f315fe ("swiotlb: Use is_swiotlb_force_bounce for swiotlb data bouncing")
> Fixes: 64e1f0c531d1 ("s390/mm: force swiotlb for protected virtualization")
> Cc: stable@vger.kernel.org #5.3+
>
> ---

Picked it up and stuck it in linux-next with the other set of patches (Will's fixes).