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 C2301C2B9F4 for ; Tue, 22 Jun 2021 08:29:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 984B960C3E for ; Tue, 22 Jun 2021 08:29:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230291AbhFVIbf (ORCPT ); Tue, 22 Jun 2021 04:31:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230062AbhFVIbf (ORCPT ); Tue, 22 Jun 2021 04:31:35 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C63D9C061574 for ; Tue, 22 Jun 2021 01:29:19 -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=LvEsSKjFfYRD98KMgPxduPWHHVC67HFD3ETX4W/7EBE=; b=aSkIPwk0gJRpsqemgW0TaoDCGM uAIlP4I+qlzMRcDZdDnzd9y/AtH+aa/4HjXRpRhNn0cBQnbzfkih4en3c74y5VwMA6xZXTDMRfS++ RDPVt7fuPBx0Cc9vj8zjvskc/mFukCKzpog+mV0EKGFTkla7JE173zhjzlc3SO4TNEcV+A+FraiZl KgGGDFXOeXwBgIW9yO2ueYiIy77J0EB5323jUeHAW6eLaIqQNeMF+Em3WR1D6olm2e+9YaM15h4Se nZl+ommgOvFr6WBx7hpqUyrAua1bwJJnCTk4e+6fHWiYI7A3jY5J3bORLyyYOGV7kLnyNgwklH0D6 r0nZMd4w==; 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 1lvbmY-006FT7-Ii; Tue, 22 Jun 2021 08:29:19 +0000 Message-ID: <32a5efc2845118e8b97f2ee61dc88a3a734cb713.camel@infradead.org> 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 09:29:16 +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="=-nou0XY5uF51llY6hNsxl" 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 --=-nou0XY5uF51llY6hNsxl Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2021-06-22 at 16:00 +0800, Jason Wang wrote: > > 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 :) >=20 >=20 > This means we need validate the userspace address each time before vhost= =20 > tries to use that. This will de-gradate the performance. So we still=20 > need to figure out the legal userspace address range which might not be= =20 > easy. Easier from the kernel than from userspace though :) But I don't know that we need it. Isn't a call to access_ok() going to be faster than what translate_desc() does to look things up anyway? In the 1:1 mode, the access_ok() is all that's needed since there's no translation. @@ -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)) { + if (!access_ok((void __user *)addr, len)) + return -EFAULT; + + iov[0].iov_len =3D len; + iov[0].iov_base =3D (void __user *)addr; + return 1; + } while ((u64)len > s) { u64 size; if (unlikely(ret >=3D iov_size)) { --=-nou0XY5uF51llY6hNsxl Content-Type: application/x-pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCECow ggUcMIIEBKADAgECAhEA4rtJSHkq7AnpxKUY8ZlYZjANBgkqhkiG9w0BAQsFADCBlzELMAkGA1UE BhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgG A1UEChMRQ09NT0RPIENBIExpbWl0ZWQxPTA7BgNVBAMTNENPTU9ETyBSU0EgQ2xpZW50IEF1dGhl 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