From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [RFC PATCH 0/2] iommu/s390: Fix iommu-groups and add sysfs support Date: Thu, 27 Apr 2017 23:03:25 +0200 Message-ID: <20170427210325.GE1332@8bytes.org> References: <1493306905-32334-1-git-send-email-joro@8bytes.org> <20170427201018.70c8be5a@thinkpad> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20170427201018.70c8be5a@thinkpad> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Gerald Schaefer Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Sebastian Ott , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org Hi Gerald, thanks for your reply. I have some more questions, please see below. On Thu, Apr 27, 2017 at 08:10:18PM +0200, Gerald Schaefer wrote: > Well, there is a separate zpci_dev for each pci_dev on s390, > and each of those has its own separate dma-table (thus not shared). Is that true for all functions of a PCIe card, so does every function of a device has its own zpci_dev structure and thus its own DMA-table? My assumption came from the fact that the zpci_dev is read from pci_dev->sysdata, which is propagated there from the pci_bridge through the pci_root_bus structures. > Given this "separate zpci_dev for each pci_dev" situation, I don't > see what this update actually changes, compared to the previous code, > see also my comments to that patch. The add_device call-back is invoked for every function of a pci-device, because each function gets its own pci_dev structure. Also we usually group all functions of a PCI-device together into one iommu-group, because we don't trust that the device isolates its functions from each other. Regards, Joerg