From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTP id 0E9E4979 for ; Fri, 9 May 2014 08:55:18 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 8E9E12031B for ; Fri, 9 May 2014 08:55:17 +0000 (UTC) Message-ID: <1399625714.879.9.camel@i7.infradead.org> From: David Woodhouse To: James Bottomley Date: Fri, 09 May 2014 09:55:14 +0100 In-Reply-To: <1399578994.2171.51.camel@dabdike.int.hansenpartnership.com> References: <1399552623.17118.22.camel@i7.infradead.org> <1399578994.2171.51.camel@dabdike.int.hansenpartnership.com> Content-Type: multipart/signed; micalg="sha-1"; protocol="application/x-pkcs7-signature"; boundary="=-v/XyHXhJqudoWgOY6lLr" Mime-Version: 1.0 Cc: "ksummit-discuss@lists.linuxfoundation.org" Subject: Re: [Ksummit-discuss] [CORE TOPIC] Device error handling / reporting / isolation List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , --=-v/XyHXhJqudoWgOY6lLr Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2014-05-08 at 12:56 -0700, James Bottomley wrote: > On Thu, 2014-05-08 at 13:37 +0100, David Woodhouse wrote: > > I'd like to have a discussion about handling device errors. > >=20 > > IOMMUs are becoming more common, and we've seen some failure modes wher= e > > we just end up with an endless stream of fault reports from a given > > device, and the kernel can do nothing else. >=20 > This is when the addresses being sent by the bus don't have IOTLB > entries? You speak as if you have a software-filled IOTLB. I'd have phrased that as "don't have page table entries". But yes, that. Or they have read-only IOTLB entries, and they're trying to write. And as I said, once we start looking at it I suspect we'll end up finding other offences that need to be taken into consideration. Which is why I think this warrants a wider discussion rather than the IOMMU owners sitting in a darkened room doing it amongst themselves. > > But I absolutely don't want us to be implementing policies like that in > > an individual IOMMU driver; this needs to be handled by generic device > > code. Once upon a time I might have said PCI code, but this is actually > > relevant for non-PCI devices too. >=20 > Right, with my PARISC hat on, our IOMMUs sit adjacent to the CPUs. The > PCI busses (if we have any) are a couple of layers down. Even the Intel IOMMU can do mappings (and take faults) for ACPI devices, these days. > > I want the IOMMU to report errors, and let the system do the appropriat= e > > thing. Which requires some discussion about what the "appropriate thing= " > > can be in various circumstances, and indeed what options are available > > to us on various platforms. > >=20 > > Participants would be those working with IOMMUs on various platforms, > > including J=C3=B6rg R=C3=B6del, myself, and hopefully someone with a fa= irly > > intimate knowledge of EEH as used on POWER systems. I note that J=C3=B6rg isn't actually on the nominations list. I think he should be... --=20 David Woodhouse Open Source Technology Centre David.Woodhouse@intel.com Intel Corporation --=-v/XyHXhJqudoWgOY6lLr Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIISxDCCBjQw ggQcoAMCAQICAR4wDQYJKoZIhvcNAQEFBQAwfTELMAkGA1UEBhMCSUwxFjAUBgNVBAoTDVN0YXJ0 Q29tIEx0ZC4xKzApBgNVBAsTIlNlY3VyZSBEaWdpdGFsIENlcnRpZmljYXRlIFNpZ25pbmcxKTAn BgNVBAMTIFN0YXJ0Q29tIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MB4XDTA3MTAyNDIxMDE1NVoX DTE3MTAyNDIxMDE1NVowgYwxCzAJBgNVBAYTAklMMRYwFAYDVQQKEw1TdGFydENvbSBMdGQuMSsw KQYDVQQLEyJTZWN1cmUgRGlnaXRhbCBDZXJ0aWZpY2F0ZSBTaWduaW5nMTgwNgYDVQQDEy9TdGFy dENvbSBDbGFzcyAxIFByaW1hcnkgSW50ZXJtZWRpYXRlIENsaWVudCBDQTCCASIwDQYJKoZIhvcN AQEBBQADggEPADCCAQoCggEBAMcJg8zOLdgasSmkLhOrlr6KMoOMpohBllVHrdRvEg/q6r8jR+EK 75xCGhR8ToREoqe7zM9/UnC6TS2y9UKTpT1v7RSMzR0t6ndl0TWBuUr/UXBhPk+Kmy7bI4yW4urC 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