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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no 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 87267C5DF60 for ; Fri, 8 Nov 2019 08:57:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4A407214DA for ; Fri, 8 Nov 2019 08:57:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="fqwZTHlJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730613AbfKHI5S (ORCPT ); Fri, 8 Nov 2019 03:57:18 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:40300 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726987AbfKHI5R (ORCPT ); Fri, 8 Nov 2019 03:57:17 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Mime-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=QYyRpsPHeR69Z3aCYkvGuNSmLiL20QAYuHafWXveSwQ=; b=fqwZTHlJRJ43aBt80AWcNj29f PBbvtSdPCwvA/wmA5cWZApdR6IkW0C4EIk721zsmibMThXxlxK4WqX+Y27T/FPQUCUBkAXQgR77wq tc24HKr6YhytMB8WOXZZ4gzxNbrte6+DpLES5oXhuupT845VzGWAykTp2HGdwZOurd3OfTtSIk/p0 ErVrb5ZjvkCOViYLR3v9dEyIg21iGpVrWhqsCsLKxty0KITzMHvvQBRsvAEP5KtRU2R9fQ+uYhZf6 SUgzdAclI9KdwzcoAlFM1yLPuLSqBVNLMOLD5xLTagCfLUk3MU8fXJKWeOHhpKePp99X8tpJfKQe3 XNyANbDVA==; Received: from [54.239.6.185] (helo=freeip.amazon.com) by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iT04v-0002tI-Pf; Fri, 08 Nov 2019 08:57:14 +0000 Message-ID: Subject: Re: [PATCH] intel-iommu: Turn off translations at shutdown From: David Woodhouse To: "Zeng, Jason" , Deepa Dinamani , "joro@8bytes.org" , "linux-kernel@vger.kernel.org" Cc: "iommu@lists.linux-foundation.org" , "Tian, Kevin" Date: Fri, 08 Nov 2019 08:57:11 +0000 In-Reply-To: <8D8B600C3EC1B64FAD4503F0B66C61F23BB95B@SHSMSX103.ccr.corp.intel.com> References: <20191107205914.10611-1-deepa.kernel@gmail.com> <1672a5861c82c2e3c0c54b5311fd413a8eee5e64.camel@infradead.org> <8D8B600C3EC1B64FAD4503F0B66C61F23BB95B@SHSMSX103.ccr.corp.intel.com> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-bAANH9QIqFdDq6Cjmsl+" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-bAANH9QIqFdDq6Cjmsl+ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2019-11-08 at 08:47 +0000, Zeng, Jason wrote: > > -----Original Message----- > > From: David Woodhouse > > Sent: Friday, November 8, 2019 3:54 PM > > To: Deepa Dinamani ; joro@8bytes.org; linux- > > kernel@vger.kernel.org > > Cc: iommu@lists.linux-foundation.org; Zeng, Jason ; > > Tian, Kevin > > Subject: Re: [PATCH] intel-iommu: Turn off translations at shutdown > >=20 > > On Thu, 2019-11-07 at 12:59 -0800, Deepa Dinamani wrote: > > > The intel-iommu driver assumes that the iommu state is > > > cleaned up at the start of the new kernel. > > > But, when we try to kexec boot something other than the > > > Linux kernel, the cleanup cannot be relied upon. > > > Hence, cleanup before we go down for reboot. > > >=20 > > > Keeping the cleanup at initialization also, in case BIOS > > > leaves the IOMMU enabled. > > >=20 > > > I considered turning off iommu only during kexec reboot, > > > but a clean shutdown seems always a good idea. But if > > > someone wants to make it conditional, we can do that. > >=20 > > This is going to break things for the VMM live update scheme that Jason > > presented at KVM Forum, isn't it? > >=20 > > In that case we rely on the IOMMU still operating during the > > transition. >=20 > For VMM live update case, we should be able to detect and bypass > the shutdown that Deepa introduced here, so keep IOMMU still operating? Is that a 'yes' to Deepa's "if someone wants to make it conditional, we can do that" ?=20 --=-bAANH9QIqFdDq6Cjmsl+ Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl bnRpY2F0aW9uIGFuZCBTZWN1cmUgRW1haWwgQ0EwHhcNMTkwMTAyMDAwMDAwWhcNMjIwMTAxMjM1 OTU5WjAkMSIwIAYJKoZIhvcNAQkBFhNkd213MkBpbmZyYWRlYWQub3JnMIIBIjANBgkqhkiG9w0B AQEFAAOCAQ8AMIIBCgKCAQEAsv3wObLTCbUA7GJqKj9vHGf+Fa+tpkO+ZRVve9EpNsMsfXhvFpb8 RgL8vD+L133wK6csYoDU7zKiAo92FMUWaY1Hy6HqvVr9oevfTV3xhB5rQO1RHJoAfkvhy+wpjo7Q cXuzkOpibq2YurVStHAiGqAOMGMXhcVGqPuGhcVcVzVUjsvEzAV9Po9K2rpZ52FE4rDkpDK1pBK+ 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