Re: [kvm-devel] [PATCH 3/8] KVM: PVDMA Guest: Guest-side routines for paravirtualized DMA

Gerd Hoffmann
2007-11-12T14:54:35Z

Muli Ben-Yehuda wrote:
> On Wed, Nov 07, 2007 at 04:21:04PM +0200, Amit Shah wrote:
>
>> We make the dma_mapping_ops structure to point to our structure so
>> that every DMA access goes through us. (This is the reason this only
>> works for 64-bit guest. 32-bit guest doesn't yet have a dma_ops
>> struct.)
>
> I need the same facility for Calgary for falling back to swiotlb if a
> translation is disabled on some slot, and IB needs the same facility
> for some IB adapters (e.g., ipath). Perhaps it's time to consider
> stackable dma-ops (unless someone has a better idea...).

Hmm, at least the later sounds like for per-device dma_ops would be more
useful that stackable ones, as each stack instance just checks "should I
do something for device $foo, if not, call the next one ...".

cheers,
Gerd