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 46C1EC6FA83 for ; Mon, 12 Sep 2022 21:41:57 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 65A6B6B0072; Mon, 12 Sep 2022 17:41:56 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5E20F8D0001; Mon, 12 Sep 2022 17:41:56 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 45A7E6B0074; Mon, 12 Sep 2022 17:41:56 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 3072C6B0072 for ; Mon, 12 Sep 2022 17:41:56 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 03FB7C0695 for ; Mon, 12 Sep 2022 21:41:55 +0000 (UTC) X-FDA: 79904756232.20.F9A6431 Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by imf22.hostedemail.com (Postfix) with ESMTP id 2829BC00BC for ; Mon, 12 Sep 2022 21:41:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663018915; x=1694554915; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=qFnIjffMALUQQUIAOVDoq6z2zOO7NBVKHgBfILKSm68=; b=ZMlv+dNPMZDZrL2oqrsW2snXaN792sPoeCPfgZSsdTmeZXMkee7RBjUK HEWimIOPMgHNiyl4snMK9a7fzUIEnmxhk4PPRfsFzIFfFzy9+3B235pOJ OLz/0bSi99e2wli3erOyWZS5fUt3N9Qd0w1ljlUzgLL/z+szYdd+awLCf C81YqQwLChfLLOh0xyvGJsXDjsp8EnVcI1Ybmi5kO16kd2q63hlE0C+IH z/Teuxb8ZpR7woqLrBurtuZ0j0Eo0+WQMXZrqamr3VoFAnvJwZxlPC8DT MkAxXkdmsBGGmyrI5jLofb6O8S2rLx/PFumCiO1dcO/t3F+ai0zu//GgD g==; X-IronPort-AV: E=McAfee;i="6500,9779,10468"; a="280994755" X-IronPort-AV: E=Sophos;i="5.93,310,1654585200"; d="scan'208";a="280994755" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Sep 2022 14:41:53 -0700 X-IronPort-AV: E=Sophos;i="5.93,310,1654585200"; d="scan'208";a="646645164" Received: from gjmurphy-mobl.ger.corp.intel.com (HELO [10.213.203.202]) ([10.213.203.202]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 12 Sep 2022 14:41:48 -0700 Message-ID: <356d4ad1-f7d8-b8ff-3b63-819a64bf5b9f@intel.com> Date: Mon, 12 Sep 2022 14:41:56 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCHv8 00/11] Linear Address Masking enabling Content-Language: en-US To: Jacob Pan , Ashok Raj Cc: "Kirill A. Shutemov" , "Kirill A. Shutemov" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ashok Raj References: <20220830010104.1282-1-kirill.shutemov@linux.intel.com> <20220904003952.fheisiloilxh3mpo@box.shutemov.name> <20220912133935.3bb3e247@jacob-builder> From: Dave Hansen In-Reply-To: <20220912133935.3bb3e247@jacob-builder> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663018915; a=rsa-sha256; cv=none; b=79S7NdGo1Ez8ANuNwu1/kS4WulojqyrWnpIZFzRb73GnkOuQRXmg8gucau0TfmbA8nVunI NL8XOztq2Pc+40GgTeBCuNKN6jJ6D0I5N9TQZpJRTJARTnt0DA//2smPdxCR0KLJmb/aEb EKXIJPvDnH4X3ediY0YbcwJqMU0taH4= ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=ZMlv+dNP; spf=pass (imf22.hostedemail.com: domain of dave.hansen@intel.com designates 134.134.136.126 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663018915; 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:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=WFq+9xupQgyWNdHZMQ1/OzWkTLfRMgITvKfbOiWVWgU=; b=hzVvSKatpl++WxmgQG+8hEkf+w26Btv3wdQsEZXrq/YemPlTeJ09PLEUZDH1XPYa4BxwUK ZYc6nq6T9+8pMP/xk2TVOt9Xq+tAfFnmgpU1wK46eAlzURnx84exl/3nOaRd6VKO74ebbj VWDr9g3iclJ5gtHAApogJmArjMkIOGQ= X-Stat-Signature: 365tn48h1dbnz3rn7bf3su1s4m15do6f X-Rspamd-Queue-Id: 2829BC00BC Authentication-Results: imf22.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=ZMlv+dNP; spf=pass (imf22.hostedemail.com: domain of dave.hansen@intel.com designates 134.134.136.126 as permitted sender) smtp.mailfrom=dave.hansen@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspam-User: X-Rspamd-Server: rspam11 X-HE-Tag: 1663018914-256857 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 9/12/22 13:39, Jacob Pan wrote: >>> + if (pasid_valid(mm->pasid) && !forced) { > I don't think this works since we have lazy pasid free. for example, > after all the devices did sva_unbind, mm->pasid we'll remain valid until > mmdrop(). LAM should be supported in this case. Nah, it works fine. It just means that the rules are "you can't do LAM if your process *EVER* got a PASID" instead of "you can't do LAM if you are actively using your PASID". We knew that PASID use would be a one-way trip for a process when we moved to the simplified implementation. This is just more fallout from that. It's fine. > Perhaps, we could introduce another prctl flag for SVA, PR_GET_SVA? > Both iommu driver and LAM can set/query the flag. LAM applications may not > be the only ones want to know if share virtual addressing is on. I don't think it's a good idea to add yet more UABI around this issue. Won't the IOMMU folks eventually get their hardware in line with LAM? Isn't this situation temporary?