From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christoph Hellwig <hch@infradead.org>
Subject: Re: [RFC 0/4] Virtio uses DMA API for all devices
Date: Sat, 4 Aug 2018 01:15:00 -0700
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: robh@kernel.org, srikar@linux.vnet.ibm.com, Benjamin Herrenschmidt <benh@kernel.crashing.org>, Will Deacon <will.deacon@arm.com>, linux-kernel@vger.kernel.org, linuxram@us.ibm.com, virtualization@lists.linux-foundation.org, Christoph Hellwig <hch@infradead.org>, paulus@samba.org, marc.zyngier@arm.com, mpe@ellerman.id.au, joe@perches.com, robin.murphy@arm.com, david@gibson.dropbear.id.au, linuxppc-dev@lists.ozlabs.org, elfring@users.sourceforge.net, haren@linux.vnet.ibm.com, Anshuman Khandual <khandual@linux.vnet.ibm.com>
List-Id: virtualization@lists.linuxfoundation.org

On Fri, Aug 03, 2018 at 10:17:32PM +0300, Michael S. Tsirkin wrote:
> It seems reasonable to teach a platform to override dma-range
> for a specific device e.g. in case it knows about bugs in ACPI.

A platform will be able override dma-range using the dev->bus_dma_mask
field starting in 4.19.  But we'll still need a way how to

  a) document in the virtio spec that all bus dma quirks are to be
     applied
  b) a way to document in a virtio-related spec how the bus handles
     dma for Ben's totally fucked up hypervisor.  Without that there
     is not way we'll get interoperable implementations.