From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5A2FC43381 for ; Thu, 28 Feb 2019 23:43:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A1246218AE for ; Thu, 28 Feb 2019 23:43:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=dell.com header.i=@dell.com header.b="pmg8gON8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729581AbfB1Xnv (ORCPT ); Thu, 28 Feb 2019 18:43:51 -0500 Received: from esa8.dell-outbound.iphmx.com ([68.232.149.218]:11700 "EHLO esa8.dell-outbound.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729146AbfB1Xnu (ORCPT ); Thu, 28 Feb 2019 18:43:50 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=dell.com; i=@dell.com; q=dns/txt; s=smtpout; t=1551397430; x=1582933430; h=from:to:cc:subject:date:message-id:references: content-transfer-encoding:mime-version; bh=QOSdfByuhtkPKEJ0cSJSD4649XeXi7jkI4EcoSByiAg=; b=pmg8gON89LffyZAmbi5dal4Q1tPlf8MO/7fhRuTgp/TaNVAHQXGG0ha6 oCy6YV8pTpK4Cb5PF+dJm/OWxQdveQ2GiVAKCRmA9TSwCqqKaTA025BTA +pAbBsdlfrwqU79pGR1SFV1lQVvpb9JCWG77PiY0deXyYXJvhKncfjw82 0=; X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: =?us-ascii?q?A2FMAADgcXhchieV50NlHAEBAQQBAQc?= =?us-ascii?q?EAQGBVAQBAQsBgVWBBoECEhUSCox3jH2BfZY3gWcLAQGEbIQ5NwYNAQMBAQM?= =?us-ascii?q?BAwIBAQIQAQEBCgkLCCkvgjoigm8BAQEBAgESKD8FCwIBCBgeEFcCBAENBQg?= =?us-ascii?q?agn6BawifQj0Cb4EBiQcBAQGCHoozjl6BEYJkLoROARIBCBeFYQKJaYIpl1g?= =?us-ascii?q?HApJiIZMch2+CbpIXAgQCBAUCFIFdgQhxcIM8gjaOJ0ABMY1mgR+BHwEB?= X-IPAS-Result: =?us-ascii?q?A2FMAADgcXhchieV50NlHAEBAQQBAQcEAQGBVAQBAQsBg?= =?us-ascii?q?VWBBoECEhUSCox3jH2BfZY3gWcLAQGEbIQ5NwYNAQMBAQMBAwIBAQIQAQEBC?= =?us-ascii?q?gkLCCkvgjoigm8BAQEBAgESKD8FCwIBCBgeEFcCBAENBQgagn6BawifQj0Cb?= =?us-ascii?q?4EBiQcBAQGCHoozjl6BEYJkLoROARIBCBeFYQKJaYIpl1gHApJiIZMch2+Cb?= =?us-ascii?q?pIXAgQCBAUCFIFdgQhxcIM8gjaOJ0ABMY1mgR+BHwEB?= Received: from mx0a-00154901.pphosted.com (HELO mx0b-00154901.pphosted.com) ([67.231.149.39]) by esa8.dell-outbound.iphmx.com with ESMTP/TLS/AES256-SHA256; 28 Feb 2019 17:43:49 -0600 Received: from pps.filterd (m0090350.ppops.net [127.0.0.1]) by mx0b-00154901.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x1SNhnif127358 for ; Thu, 28 Feb 2019 18:43:49 -0500 Received: from esa6.dell-outbound2.iphmx.com (esa6.dell-outbound2.iphmx.com [68.232.154.99]) by mx0b-00154901.pphosted.com with ESMTP id 2qxp1ghpsx-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL) for ; Thu, 28 Feb 2019 18:43:49 -0500 From: To: , Received: from ausxipps310.us.dell.com ([143.166.148.211]) by esa6.dell-outbound2.iphmx.com with ESMTP/TLS/DHE-RSA-AES256-SHA256; 01 Mar 2019 05:43:48 +0600 X-LoopCount0: from 10.166.134.87 X-IronPort-AV: E=Sophos;i="5.58,425,1544508000"; d="scan'208";a="324989107" CC: , , , , , , , , , , Subject: Re: [PATCH] nvme-pci: Prevent mmio reads if pci channel offline Thread-Topic: [PATCH] nvme-pci: Prevent mmio reads if pci channel offline Thread-Index: AQHUyksezlXXaxBLsUa+kQskBqUhAw== Date: Thu, 28 Feb 2019 23:43:46 +0000 Message-ID: <680f55f95e7547bdaffddce49772a5b7@AUSX13MPC131.AMER.DELL.COM> References: <20190225155501.GI10237@localhost.localdomain> <940d608e1a044a54abcb9d65923951f3@ausx13mps317.AMER.DELL.COM> <443262761d0e41fbb46a46dab28759c2@AUSX13MPC131.AMER.DELL.COM> <20190228141655.GA18319@infradead.org> <883e2fad8f6e4791bfee2ec08992da39@AUSX13MPC131.AMER.DELL.COM> <20190228232020.GB22003@localhost.localdomain> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.143.18.86] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-02-28_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1902280158 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2/28/2019 5:20 PM, Keith Busch wrote:=0A= > =0A= > [EXTERNAL EMAIL]=0A= > =0A= > On Thu, Feb 28, 2019 at 11:10:11PM +0000, Austin.Bolen@dell.com wrote:=0A= >> I'd also note that in PCIe, things that intentionally take the link down= =0A= >> like SBR or Link Disable suppress surprise down error reporting. But=0A= >> NSSR doesn't have this requirement to suppress surprise down reporting.= =0A= >> I think that's a gap on the part of the NVMe spec.=0A= > =0A= > SBR and Link Disable are done from the down stream port, though, so the= =0A= > host can still communicate with the function that took the link down.=0A= > That's entirely different than taking the link down from the end device,= =0A= > so I'm not sure how NVMe can fix that.=0A= > =0A= =0A= Agreed it is different. Here is one way they could have solved it: host = =0A= writes magic value to NSSRC but device latches this instead of =0A= resetting. Then require host to do SBR. When device sees SBR with =0A= magic value in NSSRC it does an NSSR.=0A= =0A= > But I can't even recall why NVMe defined NSSR to require PCIe LTSSM=0A= > Detect. That seems entirely unnecessary and is just asking for trouble.= =0A= > =0A= =0A= Not sure why but maybe they wanted a full reset of everything including =0A= the PCIe block. I can ask around. Also agree it is asking for trouble =0A= to have device take the link down without parent bridge knowing what's =0A= going on. There are new mechanism being proposed in NVMe that would =0A= also allow the device to initiate link down with no co-ordination with =0A= the parent bridge so may need to think on ways to avoid this issue for =0A= these new similar mechanisms.=0A= =0A= -Austin=0A=