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=-7.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 0E92BC2B9F4 for ; Tue, 22 Jun 2021 07:28:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DBEEA6112D for ; Tue, 22 Jun 2021 07:28:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229807AbhFVHbK (ORCPT ); Tue, 22 Jun 2021 03:31:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229574AbhFVHbJ (ORCPT ); Tue, 22 Jun 2021 03:31:09 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8B769C061574 for ; Tue, 22 Jun 2021 00:28:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=uc/oOg+qohMtGDdqTjK89ImKQ+wuZunakI3LzaMIHng=; b=3b639YfeWv50qcs1pAZWuTGLl5 ziPkRcHdtDiKwWC+8CO4jC/iEN7nIXEAqFUOgRB+3uejdNWCy9lXxNg3iY4yOZMSbdLcqNB0csc3o OGCqJO49odbgCcVXoILkenH1//yiSrQojDnSoCaMY/L1fC0AK/ZsEMMbxRU76tmxriNFr7IShhR/W BvXN8TfpGUFsy5KxCqcSn0K8LuzwUfJbFkGSG5dnyw4zpOkfaXBC79vAslNYTkhaPqe2EYScfj0mq YxDxL0S+YdMfbnMD3HFvPI07aumy49VpurQ22dBML5djFV3NEB5b6BXggmyffSuKcugbM96IWm84S ApdPZFzw==; Received: from [2001:8b0:10b:1::3ae] (helo=u3832b3a9db3152.ant.amazon.com) by bombadil.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1lvaq5-0060zQ-KN; Tue, 22 Jun 2021 07:28:54 +0000 Message-ID: Subject: Re: [PATCH] net: tun: fix tun_xdp_one() for IFF_TUN mode From: David Woodhouse To: Jason Wang , netdev Cc: Eugenio =?ISO-8859-1?Q?P=E9rez?= Date: Tue, 22 Jun 2021 08:28:51 +0100 In-Reply-To: References: <03ee62602dd7b7101f78e0802249a6e2e4c10b7f.camel@infradead.org> <2cbe878845eb2a1e3803b3340263ea14436fe053.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-xK3bi4Ghm6nie4XqFE60" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 Mime-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org --=-xK3bi4Ghm6nie4XqFE60 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2021-06-22 at 12:34 +0800, Jason Wang wrote: > >=20 > > Secondly, I need to pull numbers out of my posterior for the > > VHOST_SET_MEM_TABLE call. This works for x86_64: > >=20 > > vmem->nregions =3D 1; > > vmem->regions[0].guest_phys_addr =3D 4096; > > vmem->regions[0].memory_size =3D 0x7fffffffe000; > > vmem->regions[0].userspace_addr =3D 4096; > > if (ioctl(vpninfo->vhost_fd, VHOST_SET_MEM_TABLE, vmem) < 0) { > >=20 > > Is there a way to bypass that and just unconditionally set a 1:1 > > mapping of *all* userspace address space? >=20 >=20 > Memory Table is one of the basic abstraction of the vhost. Basically,=20 > you only need to map the userspace buffers. This is how DPDK virtio-user= =20 > PMD did. Vhost will validate the addresses through access_ok() during=20 > VHOST_SET_MEM_TABLE. >=20 > The range of all usersapce space seems architecture specific, I'm not=20 > sure if it's worth to bother. The buffers are just malloc'd. I just need a full 1:1 mapping of all "guest" memory to userspace addresses, and was trying to avoid having to map them on demand *just* because I don't know the full range of possible addresses that malloc will return, in advance. I'm tempted to add a new feature for that 1:1 access, with no ->umem or ->iotlb at all. And then I can use it as a key to know that the XDP bugs are fixed too :) --=-xK3bi4Ghm6nie4XqFE60 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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