From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
Subject: Re: [PATCH 17/20] powerpc/dma-swiotlb: use generic swiotlb_dma_ops
Date: Wed, 22 Aug 2018 09:04:07 +0200
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To: Benjamin Herrenschmidt <benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
Cc: Fenghua Yu <fenghua.yu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, Tony Luck <tony.luck-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>, linux-ia64-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Konrad Rzeszutek Wilk <konrad.wilk-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>, Michael Ellerman <mpe-Gsx/Oe8HsFggBc27wqDAHg@public.gmane.org>, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Paul Mackerras <paulus-eUNUBHrolfbYtjvyW6yDsg@public.gmane.org>, Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>, Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
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On Thu, Aug 09, 2018 at 11:57:53AM +1000, Benjamin Herrenschmidt wrote:
> Note: We will still need to implement some custom variant of this
> for our secure VMs ... 
> 
> Basically we'll need to use the existing bounce bufferring as-is but
> the condition will be different, it won't be whether the address is
> below a certain limit, it will be *always*.

The conditions are in the dma_capable() helper that the architecture
can override (and which powerpc already does override).