From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from 8bytes.org ([85.214.48.195]:45512 "EHLO mail.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754623AbaENKey (ORCPT ); Wed, 14 May 2014 06:34:54 -0400 Received: from localhost (localhost [127.0.0.1]) by mail.8bytes.org (Postfix) with SMTP id 5C25712B14F for ; Wed, 14 May 2014 12:34:53 +0200 (CEST) Date: Wed, 14 May 2014 12:34:50 +0200 From: Joerg Roedel To: Alex Williamson Cc: linux-pci@vger.kernel.org, iommu@lists.linux-foundation.org, bhelgaas@google.com, acooks@gmail.com, linux-kernel@vger.kernel.org, linux@horizon.com Subject: Re: [PATCH v3 08/15] iommu/amd: Use pci_find_dma_isolation_root() for IOMMU groups Message-ID: <20140514103449.GE6026@8bytes.org> References: <20140510145619.2997.429.stgit@bling.home> <20140510150311.2997.62903.stgit@bling.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20140510150311.2997.62903.stgit@bling.home> Sender: linux-pci-owner@vger.kernel.org List-ID: On Sat, May 10, 2014 at 09:03:11AM -0600, Alex Williamson wrote: > The expectation is that the kernel and IVRS will produce the same > result for topology based aliases while the kernel will also include > device specific DMA quirks. Is that expectation really true? There are PCIe devices out there that don't use their own device-id for requests but another one that isn't even visible as a PCI device (so the kernel has no pci_dev structure for it). The IVRS table contains such information, but I am not sure whether the PCI core finds the right requestor-id for those devices. I've seen this on PCIe cards that where the vendor just used an PCI-X chip with a PCIe-to-PCI-X bridge on the card. The PCI-X device is visible for the OS but uses the requestor-id of the invisible bridge. Joerg