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=-9.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 794FCC4338F for ; Tue, 17 Aug 2021 17:55:21 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3935660FE6 for ; Tue, 17 Aug 2021 17:55:21 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 3935660FE6 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xen.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.168003.306734 (Exim 4.92) (envelope-from ) id 1mG3It-0000y0-7e; Tue, 17 Aug 2021 17:55:11 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 168003.306734; Tue, 17 Aug 2021 17:55:11 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mG3It-0000xt-4e; Tue, 17 Aug 2021 17:55:11 +0000 Received: by outflank-mailman (input) for mailman id 168003; Tue, 17 Aug 2021 17:55:10 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mG3Is-0000xn-7f for xen-devel@lists.xenproject.org; Tue, 17 Aug 2021 17:55:10 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mG3IQ-0003Cm-CS; Tue, 17 Aug 2021 17:54:42 +0000 Received: from 54-240-197-224.amazon.com ([54.240.197.224] helo=a483e7b01a66.ant.amazon.com) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1mG3IQ-0005lD-63; Tue, 17 Aug 2021 17:54:42 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xen.org; s=20200302mail; h=Content-Transfer-Encoding:Content-Type:In-Reply-To: MIME-Version:Date:Message-ID:References:Cc:To:From:Subject; bh=3jUW37lC4D+3mq99jt5i7oRvjGGXUoup3wngpUBiTG4=; b=mrpOAEWtxUbCAIWHkcSplds1+c XAoifSQCV/FpHKYBegfhNO2UmAv1EraGRx4erwgH/EznhtbW2KNnUoecdhfeYuhF2TVviH3N+8FhF yM8PQ7NnGNotflIJzaN3R5XQ3W6IazgWJRxqLpmkSSF9FG/xTpbeyMHD1VsWvL8/BQSk=; Subject: Re: [RFC PATCH] xen/memory: Introduce a hypercall to provide unallocated space From: Julien Grall To: Oleksandr Cc: Stefano Stabellini , Andrew Cooper , xen-devel@lists.xenproject.org, Oleksandr Tyshchenko , Daniel De Graaf , "Daniel P. Smith" , Ian Jackson , Wei Liu , George Dunlap , Jan Beulich , Volodymyr Babchuk , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Bertrand Marquis , Wei Chen References: <1627489110-25633-1-git-send-email-olekstysh@gmail.com> <80fafc01-f063-d6e5-1c08-7ad64550310c@citrix.com> <4de5ed21-379e-b618-44c8-924d88b1a519@citrix.com> <6a633f4e-13e0-4a2b-cf6e-35ef90ae977c@gmail.com> <5643d414-0b76-74a4-2c37-c7a99338d547@gmail.com> <6596ad08-8398-64dd-ef62-cd7bc6f7333e@gmail.com> <1d0ea55d-2e5a-daa7-9c60-c7a1c4b48fa1@gmail.com> <6947db7a-44d3-eb5f-c93e-1c1b88c62f29@xen.org> <736c38b3-0dfa-ccbf-6a6a-6da871f8aca0@gmail.com> <4f5be55d-062b-06d2-1e41-bac3ade0cc3a@xen.org> Message-ID: <92268dd6-04b7-38e9-86d4-949702971f4b@xen.org> Date: Tue, 17 Aug 2021 18:54:39 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-GB Content-Transfer-Encoding: 7bit On 17/08/2021 18:53, Julien Grall wrote: > Hi Oleksandr, > > On 10/08/2021 18:03, Oleksandr wrote: >> >> On 10.08.21 19:28, Julien Grall wrote: >> >> Hi Julien. >> >>> >>> >>> On 09/08/2021 22:18, Oleksandr wrote: >>>> >>>> On 09.08.21 23:45, Julien Grall wrote: >>>> >>>> >>>> Hi Julien >>> >>> >>> Hi Oleksandr, >>> >>>>> On 09/08/2021 19:24, Oleksandr wrote: >>>>>> >>>>>> On 09.08.21 18:42, Julien Grall wrote: >>>>>> 1. If IOMMU is enabled for Dom0 -> provide holes found in Host DT >>>>>> as safe ranges >>>>>> >>>>>> I would take into the account holes >= 1MB. >>>>> >>>>> May I ask why 1MB? >>>> >>>> Nothing special, just thinking to not bother with small regions >>>> which would not be too useful overall, but could bloat resulting reg >>>> property. >>>> >>>> Anyway, I would be ok with any sizes. >>> >>> I was more interesting with the reasoning behind your choice rather >>> than saying we want more. >>> >>> I agree that we may want to skip smaller region. I am guess that an >>> high number of small regions will also increase the bookeeping in Linux. >>> >>> But I would probably suggest to align the safe region to a 2MB >>> (superpage for 4KB page granularity) just because the backend (or >>> even Xen) may be able to do some optimization there. >> >> OK, agree regarding the alignment. But, what about the size? I assume, >> it should be a multiple of 2MB. > > I would say yes. In the documentation for the guest, I would just write > "64KB" to give us some flexibility to reduce the alignment/size if we > encounter platform where we can meet those limits (hopefully there is > none...). Whoops, I meant cannot rather than can. Cheers, -- Julien Grall