From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tom Lyon Subject: Re: [PATCH 0/1] uio_pci_generic: extensions to allow access for non-privileged processes Date: Thu, 1 Apr 2010 08:40:34 -0700 Message-ID: <201004010840.34574.pugs@lyon-about.com> References: <201003311708.38961.pugs@lyon-about.com> <20100401125218.GE24846@8bytes.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org To: Joerg Roedel Return-path: In-Reply-To: <20100401125218.GE24846@8bytes.org> Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org 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.