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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8427CC433EF for ; Fri, 5 Nov 2021 14:12:33 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (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 0555360EFE for ; Fri, 5 Nov 2021 14:12:32 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 0555360EFE Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:51750 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mizxI-0000U4-3s for qemu-devel@archiver.kernel.org; Fri, 05 Nov 2021 10:12:32 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35810) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mizpZ-0000f0-DZ; Fri, 05 Nov 2021 10:04:33 -0400 Received: from mga06.intel.com ([134.134.136.31]:59034) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mizpT-00074P-Fx; Fri, 05 Nov 2021 10:04:33 -0400 X-IronPort-AV: E=McAfee;i="6200,9189,10158"; a="292736872" X-IronPort-AV: E=Sophos;i="5.87,212,1631602800"; d="scan'208";a="292736872" Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Nov 2021 07:04:20 -0700 X-IronPort-AV: E=Sophos;i="5.87,212,1631602800"; d="scan'208";a="450578937" Received: from lgieryk-mobl1.ger.corp.intel.com (HELO lgieryk-VirtualBox) ([10.252.39.232]) by orsmga006-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Nov 2021 07:04:17 -0700 Date: Fri, 5 Nov 2021 15:04:10 +0100 From: =?utf-8?Q?=C5=81ukasz?= Gieryk To: Klaus Jensen Subject: Re: [PATCH 12/15] hw/nvme: Initialize capability structures for primary/secondary controllers Message-ID: <20211105140401.GA5820@lgieryk-VirtualBox> References: <20211007162406.1920374-1-lukasz.maniak@linux.intel.com> <20211007162406.1920374-13-lukasz.maniak@linux.intel.com> <20211104154843.GA4639@lgieryk-VirtualBox> <20211105084615.GA5164@lgieryk-VirtualBox> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20211105084615.GA5164@lgieryk-VirtualBox> User-Agent: Mutt/1.9.4 (2018-02-28) Received-SPF: none client-ip=134.134.136.31; envelope-from=lukasz.gieryk@linux.intel.com; helo=mga06.intel.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Kevin Wolf , qemu-block@nongnu.org, Lukasz Maniak , qemu-devel@nongnu.org, Hanna Reitz , Stefan Hajnoczi , Keith Busch , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Fri, Nov 05, 2021 at 09:46:28AM +0100, Łukasz Gieryk wrote: > On Thu, Nov 04, 2021 at 04:48:43PM +0100, Łukasz Gieryk wrote: > > On Wed, Nov 03, 2021 at 01:07:31PM +0100, Klaus Jensen wrote: > > > On Oct 7 18:24, Lukasz Maniak wrote: > > > > From: Łukasz Gieryk > > > > > > > > With two new properties (sriov_max_vi_per_vf, sriov_max_vq_per_vf) one > > > > can configure the maximum number of virtual queues and interrupts > > > > assignable to a single virtual device. The primary and secondary > > > > controller capability structures are initialized accordingly. > > > > > > > > Since the number of available queues (interrupts) now varies between > > > > VF/PF, BAR size calculation is also adjusted. > > > > > > > > > > While this patch allows configuring the VQFRSM and VIFRSM fields, it > > > implicitly sets VQFRT and VIFRT (i.e. by setting them to the product of > > > sriov_max_vi_pervf and max_vfs). Which is just setting it to an upper > > > bound and this removes a testable case for host software (e.g. > > > requesting more flexible resources than what is currently available). > > > > > > This patch also requires that these parameters are set if sriov_max_vfs > > > is. I think we can provide better defaults. > > > > > > > Originally I considered more params, but ended up coding the simplest, > > user-friendly solution, because I did not like the mess with so many > > parameters, and the flexibility wasn't needed for my use cases. But I do > > agree: others may need the flexibility. Case (FRT < max_vfs * FRSM) is > > valid and resembles an actual device. > > > > > How about, > > > > > > 1. if only sriov_max_vfs is set, then all VFs get private resources > > > equal to max_ioqpairs. Like before this patch. This limits the number > > > of parameters required to get a basic setup going. > > > > > > 2. if sriov_v{q,i}_private is set (I suggested this parameter in patch > > > 10), the difference between that and max_ioqpairs become flexible > > > resources. Also, I'd be just fine with having sriov_v{q,i}_flexible > > > instead and just make the difference become private resources. > > > Potato/potato. > > > > > > a. in the absence of sriov_max_v{q,i}_per_vf, set them to the number > > > of calculated flexible resources. > > > > > > This probably smells a bit like bikeshedding, but I think this gives > > > more flexibility and better defaults, which helps with verifying host > > > software. > > > > > > If we can't agree on this now, I suggest we could go ahead and merge the > > > base functionality (i.e. private resources only) and ruminate some more > > > about these parameters. > > > > The problem is that the spec allows VFs to support either only private, > > or only flexible resources. > > > > At this point I have to admit, that since my use cases for > > QEMU/Nvme/SRIOV require flexible resources, I haven’t paid much > > attention to the case with VFs having private resources. So this SR/IOV > > implementation doesn’t even support such case (max_vX_per_vf != 0). > > > > Let me summarize the possible config space, and how the current > > parameters (could) map to these (interrupt-related ones omitted): > > > > Flexible resources not supported (not implemented): > > - Private resources for PF = max_ioqpairs > > - Private resources per VF = ? > > - (error if flexible resources are configured) > > > > With flexible resources: > > - VQPRT, private resources for PF = max_ioqpairs > > - VQFRT, total flexible resources = max_vq_per_vf * num_vfs > > - VQFRSM, maximum assignable per VF = max_vq_per_vf > > - VQGRAN, granularity = #define constant > > - (error if private resources per VF are configured) > > > > Since I don’t want to misunderstand your suggestion: could you provide a > > similar map with your parameters, formulas, and explain how to determine > > if flexible resources are active? I want to be sure we are on the > > same page. > > > > I’ve just re-read through my email and decided that some bits need > clarification. > > This implementation supports the “Flexible”-resources-only flavor of > SR/IOV, while the “Private” also could be supported. Some effort is > required to support both, and I cannot afford that (at least I cannot > commit today, neither the other Lukasz). > > While I’m ready to rework the Flexible config and prepare it to be > extended later to handle the Private variant, the 2nd version of these > patches will still support the Flexible flavor only. > > I will include appropriate TODO/open in the next cover letter. > The summary of my thoughts, so far: - I'm going to introduce sriov_v{q,i}_flexible and better defaults, according to your suggestion (as far as I understand your intentions, please correct me if I've missed something). - The Private SR/IOV flavor, if it's ever implemented, could introduce sriov_vq_private_per_vf. - The updated formulas are listed below. Flexible resources not supported (not implemented): - Private resources for PF = max_ioqpairs - Private resources per VF = sriov_vq_private_per_vf - (error if sriov_vq_flexible is set) With flexible resources: - VQPRT, private resources for PF = max_ioqpairs - sriov_vq_flexible - VQFRT, total flexible resources = sriov_vq_flexible (if set, or) VQPRT * num_vfs - VQFRSM, maximum assignable per VF = sriov_max_vq_per_vf (if set, or) VQPRT - VQGRAN, granularity = #define constant - (error if sriov_vq_private_per_vf is set) Is this version acceptable?