Re: [PATCH 0/1] uio_pci_generic: extensions to allow access for non-privileged processes

Tom Lyon
2010-04-01T15:40:34Z

On Thursday 01 April 2010 05:52:18 am Joerg Roedel wrote:
> On Wed, Mar 31, 2010 at 05:08:38PM -0700, Tom Lyon wrote:
> > uio_pci_generic has previously been discussed on the KVM list, but this
> > patch has nothing to do with KVM, so it is also going to LKML.
>
> But since you send it to the KVM list it should be suitable for KVM too,
> no?
I know not.

>
> > The point of this patch is to beef up the uio_pci_generic driver so that
> > a non-privileged user process can run a user level driver for most PCIe
> > devices. This can only be safe if there is an IOMMU in the system with
> > per-device domains. Privileged users (CAP_SYS_RAWIO) are allowed if
> > there is no IOMMU.
>
> If you rely on an IOMMU you can use the IOMMU-API instead of the DMA-API
> for dma mappings. This change makes this driver suitable for KVM use
> too. If the interface is designed clever enough we can even use it for
> IOMMU emulation for pass-through devices.
The use with privileged processes and no IOMMUs is still quite useful, so I'd
rather stick with the DMA interface.