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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id C6F2DC433EF for ; Mon, 18 Jul 2022 17:40:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 3AC326B0072; Mon, 18 Jul 2022 13:40:00 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 35C5F6B0073; Mon, 18 Jul 2022 13:40:00 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 24B5B6B0074; Mon, 18 Jul 2022 13:40:00 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 157D96B0072 for ; Mon, 18 Jul 2022 13:40:00 -0400 (EDT) Received: from smtpin30.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id E8828608B2 for ; Mon, 18 Jul 2022 17:39:59 +0000 (UTC) X-FDA: 79700933718.30.CB75999 Received: from mail-yb1-f176.google.com (mail-yb1-f176.google.com [209.85.219.176]) by imf10.hostedemail.com (Postfix) with ESMTP id 8525EC004A for ; Mon, 18 Jul 2022 17:39:59 +0000 (UTC) Received: by mail-yb1-f176.google.com with SMTP id c131so21433975ybf.9 for ; Mon, 18 Jul 2022 10:39:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=7QSlcDSCxlZGcTMOiekNXhcAWY0zL73OCKnEnPAkYA8=; b=iISCVsANHbfhrOhsm+kukh5DAnsfNo4J8I4Ont1ZwLvXUJ7gx7zzdJ2n3TEnyUf7A/ 7LDnajzeIB2s+7Um1eeAh/i2Y8yFrji2Y7fPHtX8wf4Dkjh/43+gZWcHCyq95qVyr9hx HG/F4+Ohqi9uyPRnfUTcyS+2vZd+bL/gz4D03lSLomKQzRwy2VFv5pHm5vELs2VYRCun +XGfzGPMDj3XTFU1nbQoPvz2Yv/2IT0xJi1u/HJ9zW4awqCrxnvF2QYGPB/tHbQDbc1/ SE6spqd3o9U0fTV9NM7CiVjtoppRRKefJ06w//WEDmzdDq7OaVM16oU0rStve5ai0YXU 3B+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7QSlcDSCxlZGcTMOiekNXhcAWY0zL73OCKnEnPAkYA8=; b=HXnqX+Fkmd+qxZrKnVezmhdKxl5h67JZPO4+XsmkfrWCzHLVxbfseZkuMD7CeuETMx kqswhre7kp86GeHRic65rLciFgKM05I4fTwb5yW1EMQzDrHkO9vCNgvrUg9y+A8bGZW0 KPbpIH+opeYp8jqRPtFWdQzUzQyFSQw3ls8lZtoyRCEe8d0n4/XphZqVZ2el5AXYzxCa j21Ct1pW5A+tiPOwiNi+/QubSvO3INqAFDc1aKMh2JqHV8AASx+EBbqeLc/XYENBEcMz Q4WE1bckeyaP2JJg+H8+0bw7AKZiMcXgObo5olHnfvr42b9ql03CSz3kgchCpjr/hjyM R0LQ== X-Gm-Message-State: AJIora8/KfXkov/GjCtkhg8tiPDcGVA8UJFnxMrC2SLfWcjwU00lKQwz d0ZzMjW0G8flDZDJUSxnkargrjsqtpqqvMx5s2H48A== X-Google-Smtp-Source: AGRyM1vV/bBcSPgDuXWjyYgoxUCR/wDJIcC7hW/FP0qx+/ZQz7D8lkglc65iqZGpPKusaPzX6bc9k+WeBtegqtRQSm8= X-Received: by 2002:a25:6847:0:b0:66e:b676:834c with SMTP id d68-20020a256847000000b0066eb676834cmr28349753ybc.5.1658165998681; Mon, 18 Jul 2022 10:39:58 -0700 (PDT) MIME-Version: 1.0 References: <20220712231328.5294-1-kirill.shutemov@linux.intel.com> In-Reply-To: <20220712231328.5294-1-kirill.shutemov@linux.intel.com> From: Alexander Potapenko Date: Mon, 18 Jul 2022 19:39:22 +0200 Message-ID: Subject: Re: [PATCHv5 00/13] Linear Address Masking enabling To: "Kirill A. Shutemov" Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , "the arch/x86 maintainers" , Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , Linux Memory Management List , LKML Content-Type: text/plain; charset="UTF-8" ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1658165999; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=7QSlcDSCxlZGcTMOiekNXhcAWY0zL73OCKnEnPAkYA8=; b=0runRolHinnyC/JPtpIPzXknRmK5t0tXhv12LWr1/zms6va+gYmtcIVA339LemRUPzBCCe zV5Qh/w1G5gwLerR5kSaKWBUG+9u6cspwmYE+S3CMebKwPDpcExbx56lb/rC2Pdh4k/3Hi /eEGNUwoIyB29bm2y8LSOkAgj1gKJeQ= ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=iISCVsAN; spf=pass (imf10.hostedemail.com: domain of glider@google.com designates 209.85.219.176 as permitted sender) smtp.mailfrom=glider@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1658165999; a=rsa-sha256; cv=none; b=Y6yFJdP1Z1Qz0mkUqNru1yU+FWM+8YHvu8FajPRBgHuSmfL7cRHQp9bZRU8FlRABLTtXMS XsBxw7PrQIP/U8gRImQa1MA0dd93/9rur12DvRXH+hC8851rnDaatKio+WEJWdzzTykgsd y6LRXeE+vnB4ymkE+VYhPV8f5KP6CV0= X-Stat-Signature: cyiqhnhz5nwgrkh3x9a3hk4x7afqgrb4 X-Rspamd-Queue-Id: 8525EC004A X-Rspamd-Server: rspam02 X-Rspam-User: Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=iISCVsAN; spf=pass (imf10.hostedemail.com: domain of glider@google.com designates 209.85.219.176 as permitted sender) smtp.mailfrom=glider@google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1658165999-701054 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, Jul 13, 2022 at 1:13 AM Kirill A. Shutemov wrote: > > Linear Address Masking[1] (LAM) modifies the checking that is applied to > 64-bit linear addresses, allowing software to use of the untranslated > address bits for metadata. > > The patchset brings support for LAM for userspace addresses. > > LAM_U48 enabling is controversial since it competes for bits with > 5-level paging. Its enabling isolated into an optional last patch that > can be applied at maintainer's discretion. I believe having optional patches will put unnecessary burden on distro maintainers. Soon after landing U48 support other changes will start piling on top of it, and it will be impossible to maintain a kernel with this patch removed. It also won't make any difference for the upstream, where this patch will be always present. We'd better decide now whether we need U48 or not, and either keep it or delete it.