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Mon, 17 Sep 2018 18:04:35 +0000 Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by aserv0021.oracle.com (8.14.4/8.14.4) with ESMTP id w8HI4X3o006376 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 17 Sep 2018 18:04:34 GMT Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id w8HI4Vah018273; Mon, 17 Sep 2018 18:04:31 GMT Received: from dhcp-burlington7-2nd-B-east-10-152-55-162.usdhcp.oraclecorp.com (/10.152.32.65) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 17 Sep 2018 11:04:31 -0700 Subject: Re: [Xen-devel] [PATCH V3 2/2] Xen/PCIback: Implement PCI flr/slot/bus reset with 'reset' SysFS attribute To: =?UTF-8?B?UGFzaSBLw6Rya2vDpGluZW4=?= Cc: Jan Beulich , Govinda Tatti , Juergen Gross , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, bhelgaas@google.com, xen-devel@lists.xenproject.org, roger.pau@citrix.com, Konrad Rzeszutek Wilk References: <20171207222145.9769-1-Govinda.Tatti@Oracle.COM> <20171207222145.9769-3-Govinda.Tatti@Oracle.COM> <5A2A6AB10200007800195D4F@prv-mh.provo.novell.com> <8a3bc517-1255-4547-d244-5c400e44cc77@Oracle.COM> <5A377E020200007800197FFA@prv-mh.provo.novell.com> <559ffd12-b541-8a69-60bd-fbe10e3dc159@oracle.com> <20180916114306.GF18222@reaktio.net> From: Boris Ostrovsky Openpgp: preference=signencrypt Autocrypt: addr=boris.ostrovsky@oracle.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <20180916114306.GF18222@reaktio.net> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9019 signatures=668708 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1809170179 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/16/18 7:43 AM, Pasi Kärkkäinen wrote: > Hi, > > On Mon, Dec 18, 2017 at 12:32:11PM -0500, Boris Ostrovsky wrote: >> On 12/18/2017 02:36 AM, Jan Beulich wrote: >>>>>> On 15.12.17 at 20:52, wrote: >>>>>>> +static int pcistub_device_reset(struct pci_dev *dev) >>>>>>> +{ >>>>>>> + struct xen_pcibk_dev_data *dev_data; >>>>>>> + bool slot = false, bus = false; >>>>>>> + struct pcistub_args arg = {}; >>>>>>> + >>>>>>> + if (!dev) >>>>>>> + return -EINVAL; >>>>>>> + >>>>>>> + dev_dbg(&dev->dev, "[%s]\n", __func__); >>>>>>> + >>>>>>> + /* First check and try FLR */ >>>>>>> + if (pcie_has_flr(dev)) { >>>>>>> + dev_dbg(&dev->dev, "resetting %s device using FLR\n", >>>>>>> + pci_name(dev)); >>>>>>> + pcie_flr(dev); >>>>>> The lack of error check here puzzled me, but I see the function >>>>>> indeed returns void right now. I think the prereq patch should >>>>>> change this along with exporting the function - you really don't >>>>>> want the device to be handed to a guest when the FLR timed >>>>>> out. >>>>> We will change pcie_flr() to return error code. I will make this change >>>>> in the next version of this patch. >>>> I exchanged some emails with Bjorn/Christoph and it looks like Christoph >>>> as some planto restructure pcie flr specific functions but I don't know >>>> the exact time-frame. For now,I am planning to use existing pcie_flr() >>>> after checking FLR capability. We will switchto revised pcie_flr() once >>>> it is available. >>>> >>>> I hope you are fine with this approach. Please let me know. Thanks. >>> I've seen that other discussion. I don't think the change here >>> should be done prior to the error reporting being put in place, >>> for security reasons. But in the end it'll be Konrad as the >>> maintainer to judge. >>> >>> Or wait, looks like there's some confusion in ./MAINTAINERS: >>> Konrad is listed as maintainer for "XEN PCI SUBSYSTEM", but the >>> list of files doesn't include pciback. So it would instead be Boris >>> or Jürgen to give you a final word. >> >> This is now 4.16 material so we can at least wait until closer to >> opening of the merge window when we may have the PCI updates. (And I >> just noticed that you responded to Christoph.) >> >> Besides, we don't want to make kernel changes until the interface is >> settled (i.e the toolstack changes are accepted). >> > It seems Govinda's email address is giving an error, so I assume someone else needs to pick up this pciback 'reset' feature. > Is it likely someone else from Oracle can/will pick up and refresh this patch, with the review comments addressed? Govinda is no longer at Oracle. What about the toolstack changes? Have they been accepted? I vaguely recall there was a discussion about those changes but don't remember how it ended. -boris > > > Meanwhile the pcie_has_flr() has been exported in upstream Linux kernel, so that's already available for use now. > > "PCI: Export pcie_has_flr()": > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=2d2917f7747805a1f4188672f308d82a8ba01700 > > >