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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id B3336C433EF for ; Fri, 17 Jun 2022 08:17:09 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.351099.577606 (Exim 4.92) (envelope-from ) id 1o279z-0004tE-24; Fri, 17 Jun 2022 08:16:55 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 351099.577606; Fri, 17 Jun 2022 08:16:55 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1o279y-0004t7-VE; Fri, 17 Jun 2022 08:16:54 +0000 Received: by outflank-mailman (input) for mailman id 351099; Fri, 17 Jun 2022 08:16:53 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1o279x-0004su-FU for xen-devel@lists.xenproject.org; Fri, 17 Jun 2022 08:16:53 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1o279w-0006Bj-KC; Fri, 17 Jun 2022 08:16:52 +0000 Received: from 54-240-197-232.amazon.com ([54.240.197.232] helo=[192.168.0.243]) by xenbits.xenproject.org with esmtpsa (TLS1.3:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.92) (envelope-from ) id 1o279w-0005Z2-Cy; Fri, 17 Jun 2022 08:16:52 +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:From: References:Cc:To:Subject:MIME-Version:Date:Message-ID; bh=ychhPBjESfktqZuqgD7DpY1PUlkzuhKF23PbFWiNdv0=; b=s+A2QN7fQUJeAoOivDV5IEiJQv TgyCAFthIDsR4feU+7DKEyAit8tT+3jh5kV3wzgIMgq6pFenV3Q3vx7pi2cvtZQy9OFCgNAOb/uvr OnvlXtLR+gWG8ivQOly1UHWMQ+ERcZX+VCLNGJXLon6jiCPdWzvwwkPA11+iIvljHNK0=; Message-ID: <94122e8d-224d-2632-27ad-d56d3a24b367@xen.org> Date: Fri, 17 Jun 2022 09:16:50 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.10.0 Subject: Re: [PATCH v2 2/2] xen/arm: add FF-A mediator To: Jens Wiklander , Volodymyr Babchuk Cc: "xen-devel@lists.xenproject.org" , Stefano Stabellini References: <20220609061812.422130-1-jens.wiklander@linaro.org> <20220609061812.422130-3-jens.wiklander@linaro.org> <874k0nhvsq.fsf@epam.com> <20220616223728.GA71444@jade> From: Julien Grall In-Reply-To: <20220616223728.GA71444@jade> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Jens, On 16/06/2022 23:37, Jens Wiklander wrote: > On Tue, Jun 14, 2022 at 07:47:18PM +0000, Volodymyr Babchuk wrote: >> >> Hello Jens, >> >> Sorry for late review, I was busy with internal projects. >> >> This is preliminary review. I gave up at scatter-gather operations. Need >> more time to review them properly. > > No problem, thanks for taking the time. > >> >> One thing that bothers me is that Xen is non-preemptive and there are >> plenty potentially long-running operations. > > There's room to deal with that in the FF-A specification. These scatter > gather operation are quite complicated so I started with the minimum. We > can as a future optimization address the problem with long running > operations. I would be OK to defer this work. However, I think this should be written down as Xen community will not be able to security support until we resolved the known places where a vCPU may hog pCPU longer than necessary. This reminds me that this series doesn't add a support statement for the new subsystem in SUPPORT.md. AFAICT, this should be tech preview for now. Cheers, -- Julien Grall