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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 088A0C433B4 for ; Fri, 9 Apr 2021 14:12:16 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9724B61007 for ; Fri, 9 Apr 2021 14:12:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9724B61007 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=shutemov.name Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 32F676B006C; Fri, 9 Apr 2021 10:12:15 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2DF446B006E; Fri, 9 Apr 2021 10:12:15 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 159A56B0070; Fri, 9 Apr 2021 10:12:15 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0019.hostedemail.com [216.40.44.19]) by kanga.kvack.org (Postfix) with ESMTP id EBAC06B006C for ; Fri, 9 Apr 2021 10:12:14 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 99E2B1817903A for ; Fri, 9 Apr 2021 14:12:14 +0000 (UTC) X-FDA: 78013018188.15.E02A556 Received: from mail-lj1-f171.google.com (mail-lj1-f171.google.com [209.85.208.171]) by imf13.hostedemail.com (Postfix) with ESMTP id D8A84E000123 for ; Fri, 9 Apr 2021 14:12:11 +0000 (UTC) Received: by mail-lj1-f171.google.com with SMTP id o16so6643071ljp.3 for ; Fri, 09 Apr 2021 07:12:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=shutemov-name.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=NDsvXUdltGvvpLLyVAvKO+pIIX+hnM4/5t6QQsKamX4=; b=KIx+P5g+pGir5D4L/bl008ypkOLxkw9EMUHHovL+BOej8xyb0weCq1XijtSDfDpTFA SqMYfgMvQiJW4sfTBLebyhjCFW7UpdD4b0Evc1txWo0q3ACeRe8vHAnTP/xsXN7tCznb lq0qYYe3ZsK2lONfy+hLR3ywcj7L0C3h20w8vffd0U14WwWJrAhEqlATTAc1iTFKeWcC 5vRsEUQTcR0Ze97CB1m/XctanDdaeVKwhfbKioYUG7rBgq7QA20GQmSLB8tSI4g4f5Rp qixidefXZQiEvkqMSeMSLFhbuCinCREOfV4po/6LpNF6wd9hPaz8xPsoYWp87DcyCDoS 6hnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=NDsvXUdltGvvpLLyVAvKO+pIIX+hnM4/5t6QQsKamX4=; b=l31aKfF08fA5eD+pW1HM1gwJM64AmeIH7iQJyj44PEoTLc1+S3JvYf1b6KK42LccrG 5QY91afjnVUg2h0fICQgJt2G17L65g/197c2tkERUu8+Y4vHM3jPf1DJOZtcuhTa9+Lp /It34nBJIfSxkX+jHDo1JZ2jqiOavUYhYCduMgWtVMvWh0skBQ9iMc4w+ffgDoAHRKnh E2soV5X6ocnn1/SXelxwOOszocdq855jnhIlmyAEOmK6O2ads4uAkR5sPBUlSa8S6/eg 2nsO2v+8BC6aAXx8FrR4MTJPy6xSAATiAOSNf6YveGFiTkT/kI/nRYNH1765bgvA/gvg 4iQQ== X-Gm-Message-State: AOAM530pUFYn8MU/K8bUXvJMCu4BQ4nVYUTJABZY9gts83MsQGcwL56o 99228TRDjjJbFBlRbM8dVgh5FQ== X-Google-Smtp-Source: ABdhPJygMC32GdhqTvZsDSgSixX9aK7vPRPI1+Ns5bn6Vxj6vZL4UquVC6LKIQ8m6/0BYLMDzKTNBQ== X-Received: by 2002:a05:651c:200b:: with SMTP id s11mr9021619ljo.177.1617977532354; Fri, 09 Apr 2021 07:12:12 -0700 (PDT) Received: from box.localdomain ([86.57.175.117]) by smtp.gmail.com with ESMTPSA id r23sm282443lfm.73.2021.04.09.07.12.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 09 Apr 2021 07:12:11 -0700 (PDT) Received: by box.localdomain (Postfix, from userid 1000) id 1B878102498; Fri, 9 Apr 2021 17:12:11 +0300 (+03) Date: Fri, 9 Apr 2021 17:12:11 +0300 From: "Kirill A. Shutemov" To: David Hildenbrand Cc: Dave Hansen , Andy Lutomirski , Peter Zijlstra , Sean Christopherson , Jim Mattson , David Rientjes , "Edgecombe, Rick P" , "Kleen, Andi" , "Yamahata, Isaku" , x86@kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" , Oscar Salvador , Naoya Horiguchi Subject: Re: [RFCv1 7/7] KVM: unmap guest memory using poisoned pages Message-ID: <20210409141211.wfbyzflj7ygtx7ex@box.shutemov.name> References: <20210402152645.26680-1-kirill.shutemov@linux.intel.com> <20210402152645.26680-8-kirill.shutemov@linux.intel.com> <5e934d94-414c-90de-c58e-34456e4ab1cf@redhat.com> <20210409133347.r2uf3u5g55pp27xn@box> <5ef83789-ffa5-debd-9ea2-50d831262237@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5ef83789-ffa5-debd-9ea2-50d831262237@redhat.com> X-Rspamd-Queue-Id: D8A84E000123 X-Stat-Signature: b4akwteqpupnokuuiyfxm3fu6tn88cfs X-Rspamd-Server: rspam02 Received-SPF: none (shutemov.name>: No applicable sender policy available) receiver=imf13; identity=mailfrom; envelope-from=""; helo=mail-lj1-f171.google.com; client-ip=209.85.208.171 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617977531-813613 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 Fri, Apr 09, 2021 at 03:50:42PM +0200, David Hildenbrand wrote: > > > 3. Allow selected users to still grab the pages (esp. KVM to fault them into > > > the page tables). > > > > As long as fault leads to non-present PTEs we are fine. Usespace still may > > want to mlock() some of guest memory. There's no reason to prevent this. > > I'm curious, even get_user_pages() will lead to a present PTE as is, no? So > that will need modifications I assume. (although I think it fundamentally > differs to the way get_user_pages() works - trigger a fault first, then > lookup the PTE in the page tables). For now, the patch has two step poisoning: first fault in, on the add to shadow PTE -- poison. By the time VM has chance to use the page it's poisoned and unmapped from the host userspace. -- Kirill A. Shutemov