Re: [PATCH] VFIO driver: Non-privileged user level PCI drivers

[Avi Kivity]

On 06/02/2010 12:45 PM, Joerg Roedel wrote:
> On Tue, Jun 01, 2010 at 03:41:55PM +0300, Avi Kivity wrote:
>    
> > On 06/01/2010 01:46 PM, Michael S. Tsirkin wrote:
> >      
>    
> > > Main difference is that vhost works fine with unlocked
> > > memory, paging it in on demand. iommu needs to unmap
> > > memory when it is swapped out or relocated.
> > >
> > >        
> > So you'd just take the memory map and not pin anything.  This way you
> > can reuse the memory map.
> >
> > But no, it doesn't handle the dirty bitmap, so no go.
> >      
> IOMMU mapped memory can not be swapped out because we can't do demand
> paging on io-page-faults with current devices. We have to pin _all_
> userspace memory that is mapped into an IOMMU domain.
>    

vhost doesn't pin memory.

What I proposed is to describe the memory map using an object (fd), and 
pass it around to clients that use it: kvm, vhost, vfio.  That way you 
maintain the memory map in a central location and broadcast changes to 
clients.  Only a vfio client would result in memory being pinned.

It can still work, but the interface needs to be extended to include 
dirty bitmap logging.

--
error compiling committee.c: too many arguments to function

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/