From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:39783 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753900AbbINQyP (ORCPT ); Mon, 14 Sep 2015 12:54:15 -0400 Message-ID: <1442249653.23936.17.camel@redhat.com> Subject: Re: [RFC PATCH] vfio/pci: Use kernel VPD access functions From: Alex Williamson To: "Rustad, Mark D" Cc: "kvm@vger.kernel.org" , "linux-pci@vger.kernel.org" , "alexander.h.duyck@redhat.com" , "myron.stowe@redhat.com" , "linux-kernel@vger.kernel.org" Date: Mon, 14 Sep 2015 10:54:13 -0600 In-Reply-To: <80CE59CA-1B93-42FF-96D1-6276B724203F@intel.com> References: <20150911181332.32399.74472.stgit@gimli.home> <80CE59CA-1B93-42FF-96D1-6276B724203F@intel.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org List-ID: On Sat, 2015-09-12 at 01:11 +0000, Rustad, Mark D wrote: > Alex, > > > On Sep 11, 2015, at 11:16 AM, Alex Williamson wrote: > > > > RFC - Is this something we should do? > > Superficially this looks pretty good. I need to think harder to be sure of the details. > > > Should we consider providing > > similar emulation through PCI sysfs to allow lspci to also make use > > of the vpd interfaces? > > It looks to me like lspci already uses the vpd attribute in sysfs to access VPD, so maybe nothing more than this is needed. No doubt lspci can be coerced into accessing VPD directly, but is that really worth going after? I'm not so sure. > > An strace of lspci accessing a device with VPD shows me: > > write(1, "\tCapabilities: [e0] Vital Produc"..., 39 Capabilities: [e0] Vital Product Data > ) = 39 > open("/sys/bus/pci/devices/0000:02:00.0/vpd", O_RDONLY) = 4 > ----------------------------------------^^^ accesses to this should be safe, I think > > pread(4, "\202", 1, 0) = 1 > pread(4, "\10\0", 2, 1) = 2 > pread(4, "PVL Dell", 8, 3) = 8 > write(1, "\t\tProduct Name: PVL Dell\n", 25 Product Name: PVL Dell > ) = 25 > > and so forth. Oh good, so aside from some rouge admin poking around with setpci access through pci-sysfs is hopefully not an issue. Thanks for looking into it. Alex