Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756713Ab3JHXff (ORCPT ); Tue, 8 Oct 2013 19:35:35 -0400 Received: from co9ehsobe005.messaging.microsoft.com ([207.46.163.28]:58759 "EHLO co9outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755492Ab3JHXfd (ORCPT ); Tue, 8 Oct 2013 19:35:33 -0400 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: -3 X-BigFish: VS-3(zz98dI936eI1432Izz1f42h208ch1ee6h1de0h1fdah2073h1202h1e76h1d1ah1d2ah1fc6hzzz2dh2a8h839h93fhd24hf0ah1288h12a5h12a9h12bdh137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1946h19b5h1ad9h1b0ah1b2fh1fb3h1d0ch1d2eh1d3fh1dfeh1dffh1e23h1fe8h1ff5h1155h) Message-ID: <1381275325.7979.320.camel@snotra.buserror.net> Subject: Re: [PATCH 1/7] powerpc: Add interface to get msi region information From: Scott Wood To: Bjorn Helgaas CC: Bharat Bhushan , "alex.williamson@redhat.com" , Joerg Roedel , Benjamin Herrenschmidt , Kumar Gala , "linux-kernel@vger.kernel.org" , linuxppc-dev , "linux-pci@vger.kernel.org" , Alexander Graf , "open list:INTEL IOMMU (VT-d)" , Bharat Bhushan Date: Tue, 8 Oct 2013 18:35:25 -0500 In-Reply-To: References: <1379575763-2091-1-git-send-email-Bharat.Bhushan@freescale.com> <1379575763-2091-2-git-send-email-Bharat.Bhushan@freescale.com> <1381273037.7979.298.camel@snotra.buserror.net> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-OriginatorOrg: freescale.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1554 Lines: 33 On Tue, 2013-10-08 at 17:25 -0600, Bjorn Helgaas wrote: > >> - u32 msiir_offset; /* Offset of MSIIR, relative to start of CCSR */ > >> + dma_addr_t msiir; /* MSIIR Address in CCSR */ > > > > Are you sure dma_addr_t is right here, versus phys_addr_t? It implies > > that it's the output of the DMA API, but I don't think the DMA API is > > used in the MSI driver. Perhaps it should be, but we still want the raw > > physical address to pass on to VFIO. > > I don't know what "msiir" is used for, but if it's an address you > program into a PCI device, then it's a dma_addr_t even if you didn't > get it from the DMA API. Maybe "bus_addr_t" would have been a more > suggestive name than "dma_addr_t". That said, I have no idea how this > relates to VFIO. It's a bit awkward because it gets used both as something to program into a PCI device (and it's probably a bug that the DMA API doesn't get used), and also (if I understand the current plans correctly) as a physical address to give to VFIO to be a destination address in an IOMMU mapping. So I think the value we keep here should be a phys_addr_t (it comes straight from the MMIO address in the device tree), which gets trivially turned into a dma_addr_t by the non-VFIO code path because there's currently no translation there. -Scott -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/