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 C96F3C10DCE for ; Fri, 6 Mar 2020 11:53:33 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 97D0E2073B for ; Fri, 6 Mar 2020 11:53:33 +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="XhbmJlgf" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 97D0E2073B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jABXQ-0001Dv-5C; Fri, 06 Mar 2020 11:53:08 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1jABXO-0001Dq-Vg for xen-devel@lists.xenproject.org; Fri, 06 Mar 2020 11:53:07 +0000 X-Inumbo-ID: 066ee1e4-5fa1-11ea-90c4-bc764e2007e4 Received: from merlin.infradead.org (unknown [2001:8b0:10b:1231::1]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 066ee1e4-5fa1-11ea-90c4-bc764e2007e4; Fri, 06 Mar 2020 11:53:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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; bh=8IrH4rzLgxGHqQQ7+ik+6yAvYklYEsoiVpmA0phCkX4=; b=XhbmJlgfrLM5nMot9g8yPOgpg1 pw0dT5Ps/+0fwOciuv5IOpWElewxvaC9YfUV/ESHP2w7gqS7g89hxZkV2bXSbfDNf02excs3FVWpR 7Icqh3en547/uBOiy6EJbDsBy/u2DGOjaYhzjmC8W+BcvW3U1orSvn9E7cHV6rXzE8+TTEQdIM8Ps SbotC/K3hlhEtTBLaPOvaMdFDHO7uNu+GnyFj3Zxx3z1Hl9feIWmzwgLLkhEugX0mo9rebPPikNzX hT81hxHXn4+cR/5R6EJVRYmq+ZI4ut3Y+7lvxz0+ZJDeGDsF33C0nXe8IYHBziRG244kKhFXxUn0Z jc0DPouw==; Received: from 54-240-197-234.amazon.com ([54.240.197.234] helo=freeip.amazon.com) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jABWx-0005QA-Rt; Fri, 06 Mar 2020 11:52:40 +0000 Message-ID: <6e43af74fbdb712d7b9785c1cffdc43aadfafb3c.camel@infradead.org> From: David Woodhouse To: Jan Beulich , "Durrant, Paul" Date: Fri, 06 Mar 2020 13:52:37 +0200 In-Reply-To: <7de58cb0-d8b5-ea86-f573-151356edbb79@suse.com> References: <20200225095357.3923-1-pdurrant@amazon.com> <20200225095357.3923-3-pdurrant@amazon.com> <2653c2cf-9add-dd0c-03e5-36d951ee621e@suse.com> <132bb159fcf049ae87e402537ccc7d2a@EX13D32EUC003.ant.amazon.com> <7170eda8579cc4c9e6a899980a87e0eb0e9c71cd.camel@amazon.co.uk> <7de58cb0-d8b5-ea86-f573-151356edbb79@suse.com> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by merlin.infradead.org. See http://www.infradead.org/rpr.html Subject: Re: [Xen-devel] [PATCH 2/2] domain: use PGC_extra domheap page for shared_info X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: "sstabellini@kernel.org" , "julien@xen.org" , "wl@xen.org" , "konrad.wilk@oracle.com" , "andrew.cooper3@citrix.com" , "ian.jackson@eu.citrix.com" , "george.dunlap@citrix.com" , "xen-devel@lists.xenproject.org" , "Volodymyr_Babchuk@epam.com" Content-Type: multipart/mixed; boundary="===============4809700696809762154==" Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" --===============4809700696809762154== Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-KyIG46U/YpOjb09Xv8nX" --=-KyIG46U/YpOjb09Xv8nX Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2020-03-06 at 12:37 +0100, Jan Beulich wrote: > I've started looking at the latest version of Paul's series, but I'm > still struggling to see the picture: There's no true distinction > between Xen heap and domain heap on x86-64 (except on very large > systems). Therefore it is unclear to me what "those pages" is actually > referring to above. Surely new Xen can't be given any pages in use > _in any way_ by old Xen, no matter whether it's ones assigned to > domains, or ones used internally to (old) Xen. Old and new Xen do not coexist. There is a kexec (via kexec_reloc.S and purgatory) from old to new. There are some pages which new Xen MUST NOT scribble on, because they actually belong to the domains being preserved. That includes the EPT (or at least IOMMU) page tables. I suppose new Xen also mustn't scribble on the pages in which old Xen has placed the migration information for those domains either. At least, not until it's consumed the data. Anything else, however, is fine for new Xen to scribble on. Fairly much anything that the old Xen had allocated from its xenheap (and not subsequently shared to a guest, qv) is no longer required and can be treated as free memory by the new Xen, which now owns the machine. --=-KyIG46U/YpOjb09Xv8nX 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 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