From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752091Ab0GAEQs (ORCPT ); Thu, 1 Jul 2010 00:16:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40830 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750706Ab0GAEQr (ORCPT ); Thu, 1 Jul 2010 00:16:47 -0400 Subject: Re: [PATCH V2] VFIO driver: Non-privileged user level PCI drivers From: Alex Williamson To: Tom Lyon Cc: randy.dunlap@oracle.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, chrisw@sous-sol.org, joro@8bytes.org, hjk@linutronix.de, mst@redhat.com, avi@redhat.com, gregkh@suse.de, aafabbri@cisco.com, scofeldm@cisco.com In-Reply-To: <4c0eb470.1HMjondO00NIvFM6%pugs@cisco.com> References: <4c0eb470.1HMjondO00NIvFM6%pugs@cisco.com> Content-Type: text/plain; charset="UTF-8" Date: Wed, 30 Jun 2010 22:16:23 -0600 Message-ID: <1277957783.10112.15.camel@x201> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-06-08 at 14:21 -0700, Tom Lyon wrote: > +int vfio_dma_unmap_dm(struct vfio_listener *listener, struct vfio_dma_map *dmp) > +{ > + unsigned long start, npage; > + struct dma_map_page *mlp; > + struct list_head *pos, *pos2; > + int ret; > + > + start = dmp->vaddr & ~PAGE_SIZE; > + npage = dmp->size >> PAGE_SHIFT; > + > + ret = -ENXIO; > + mutex_lock(&listener->vdev->dgate); > + list_for_each_safe(pos, pos2, &listener->dm_list) { > + mlp = list_entry(pos, struct dma_map_page, list); > + if (dmp->vaddr != mlp->vaddr || mlp->npage != npage) > + continue; > + ret = 0; > + vfio_dma_unmap(listener, mlp); > + break; > + } Hi Tom, Shouldn't we be matching the mlp based on daddr instead of vaddr? We can have multiple dma address pointing at the same virtual address, so dma address is the unique element. I'm also nervous about this dm_list. For qemu device assignment, we're potentially statically mapping many GB of iova space. It seems like this could get incredibly bloated and slow. Thanks, Alex