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=-12.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 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 E52E5C48BDF for ; Thu, 24 Jun 2021 12:39:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BAF37613FF for ; Thu, 24 Jun 2021 12:39:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231453AbhFXMl6 (ORCPT ); Thu, 24 Jun 2021 08:41:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231432AbhFXMl5 (ORCPT ); Thu, 24 Jun 2021 08:41:57 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E2B5C061574 for ; Thu, 24 Jun 2021 05:39:37 -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=B5GQLp4yCeTjPcV3KC9F17xGnAJkcnS/FbvflYnWNZo=; b=V35+YF83Qm6nCZxgL1sBGetWKK 451hGyg6xqedqH5dBJXgBioYP2vrTr19rJVkvJ+ZXFlcHAcakpJZdmIs889VmF5Qs9JH9ooG+gTEf upDA/db8ULB0O7qDsUunjKeid2astY4f9YRULk+GOZyKRQ3xEOKpW2Y7RHXf4UgetHavZ8nfxwbm9 rVxwdGPi9pcGV3G69m8FPo1iYhBZyDB+YvC0TUV4ZPNI4KfF8o/RpUYyCqKJ1sm15FGhnwYVXbn7Y VGmPrtQdRJ2a5CW7tk2BhoF5sRhKfDKFBfjw2ociKgXY5kVe8qZlzC5s7QfuKGJ1JPXRQlWmcJKGW 2UUcVG9Q==; 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 1lwOds-00EdnO-JK; Thu, 24 Jun 2021 12:39:36 +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: Thu, 24 Jun 2021 13:39:34 +0100 In-Reply-To: References: <03ee62602dd7b7101f78e0802249a6e2e4c10b7f.camel@infradead.org> <2cbe878845eb2a1e3803b3340263ea14436fe053.camel@infradead.org> <32a5efc2845118e8b97f2ee61dc88a3a734cb713.camel@infradead.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/x-pkcs7-signature"; boundary="=-MmOoC7GuLcfhbDlqdlE9" 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 --=-MmOoC7GuLcfhbDlqdlE9 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2021-06-23 at 11:39 +0800, Jason Wang wrote: > >=20 > > In the 1:1 mode, the access_ok() is all that's needed since there's no > > translation. > >=20 > > @@ -2038,6 +2065,14 @@ static int translate_desc(struct vhost_virtqueue= *vq, u64 addr, u32 len, > > u64 s =3D 0; > > int ret =3D 0; > > =20 > > + if (vhost_has_feature(vq, VHOST_F_IDENTITY_MAPPING)) { >=20 >=20 > Using vhost_has_feature() is kind of tricky since it's used for virtio= =20 > feature negotiation. >=20 > We probably need to use backend_features instead. >=20 > I think we should probably do more: >=20 > 1) forbid the feature to be set when mem table / IOTLB has at least one= =20 > mapping > 2) forbid the mem table / IOTLB updating after the feature is set Yes, that all makes sense. I confess I hadn't actually *implemented* the feature at all; the only time I'd typed 'VHOST_F_IDENTITY_MAPPING' was to show that snippet of "patch" as an example of what translate_desc() would do. I just wanted *something* to put in the 'if()' statement as a placeholder, so I used that. It could *even* have just been 'if (!umem)' but that might let it happen by *accident* which probably isn't a good idea. --=-MmOoC7GuLcfhbDlqdlE9 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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