From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH v3 08/15] iommu/amd: Use pci_find_dma_isolation_root() for IOMMU groups Date: Wed, 14 May 2014 12:34:50 +0200 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 Return-path: Content-Disposition: inline In-Reply-To: <20140510150311.2997.62903.stgit@bling.home> Sender: linux-pci-owner@vger.kernel.org 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 List-Id: iommu@lists.linux-foundation.org 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