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 ws5-mx01.kavi.com (ws5-mx01.kavi.com [34.193.7.191]) (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 9D002C0015E for ; Thu, 29 Jun 2023 11:48:16 +0000 (UTC) Received: from lists.oasis-open.org (oasis.ws5.connectedcommunity.org [10.110.1.242]) by ws5-mx01.kavi.com (Postfix) with ESMTP id 10C1C3427 for ; Thu, 29 Jun 2023 11:48:16 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 04CF0986633 for ; Thu, 29 Jun 2023 11:48:16 +0000 (UTC) Received: from host09.ws5.connectedcommunity.org (host09.ws5.connectedcommunity.org [10.110.1.97]) by lists.oasis-open.org (Postfix) with QMQP id ED4D69865AA; Thu, 29 Jun 2023 11:48:15 +0000 (UTC) Mailing-List: contact virtio-dev-help@lists.oasis-open.org; run by ezmlm List-ID: Sender: Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id D857E9865D5 for ; Thu, 29 Jun 2023 11:48:13 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: nPQgdyjdOu-8x4xOFDfqJQ-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688039289; x=1690631289; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=r0mcyIzaxFbROoBjB5w5oJfKWv4ZvlXNmrlOchvGg1k=; b=knp+LvThUizTX4bCunRCTjkejb3iw3JEbpvrrfI0WLsIRdxi2sGV4KU2GiVTKM9COu aQKgqTpxra3gQPhcVKBaPeDn5uSQ8SohY6xRSngtYY5lmgPjdnY9G2j2/IzOfcUXEwfR W3//zt/y942KzorGyrAjxXpOVLtCikx4mVjk98kBl/3EHhQtMOY1QIGb/uYusHz23Fnw jNZXwucGtIiSJdVMt4cDn4mZSlVGEd2Z0ukR3BaqU5Q7k4EYvYqZkqZA6LtnuTKM0ArD lwCDgI+N7o/hTDwsxtVCUd4EQ81Jci4UCpA72G5q0gPjQ3uzeROSDVrlmvtdDx3SK6GG lbYw== X-Gm-Message-State: AC+VfDwdhdHaq72DdxMkbXUNPHU5qQpaqRwxelHfd42SNEtm6S4SRybw ZLer9i+nXjB304dN/q57rqOmIHnwDUBGy37zHS6lazfRtKS51B9qsClfopuDWdMk/bfL5OOEr+3 9cHxd76oT4vTDHc0jvEpj+9Wz0Cjf X-Received: by 2002:a05:600c:2154:b0:3fa:9348:51a8 with SMTP id v20-20020a05600c215400b003fa934851a8mr8426134wml.23.1688039289281; Thu, 29 Jun 2023 04:48:09 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5Dt1HYrrMzp4pv+qcMvpPPWGDIJR6IuA+KNZPraiSgx+pWA1V8NGkHwtf/vdxv9HwrbhpPYQ== X-Received: by 2002:a05:600c:2154:b0:3fa:9348:51a8 with SMTP id v20-20020a05600c215400b003fa934851a8mr8426120wml.23.1688039288941; Thu, 29 Jun 2023 04:48:08 -0700 (PDT) Date: Thu, 29 Jun 2023 07:48:04 -0400 From: "Michael S. Tsirkin" To: Heng Qi Cc: Parav Pandit , Jason Wang , "virtio-comment@lists.oasis-open.org" , "virtio-dev@lists.oasis-open.org" , Yuri Benditovich , Xuan Zhuo Message-ID: <20230629074627-mutt-send-email-mst@kernel.org> References: <20230628061257-mutt-send-email-mst@kernel.org> <20230628123131-mutt-send-email-mst@kernel.org> <20230628132122-mutt-send-email-mst@kernel.org> <20230628152125-mutt-send-email-mst@kernel.org> <4132affe-9b97-a81f-ad57-50ed4341678b@linux.alibaba.com> MIME-Version: 1.0 In-Reply-To: <4132affe-9b97-a81f-ad57-50ed4341678b@linux.alibaba.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Subject: [virtio-dev] Re: [virtio-comment] RE: [PATCH v19] virtio-net: support inner header hash On Thu, Jun 29, 2023 at 10:05:09AM +0800, Heng Qi wrote: > > > 在 2023/6/29 上午9:56, Parav Pandit 写道: > > > > > From: Michael S. Tsirkin > > > Sent: Wednesday, June 28, 2023 3:45 PM > > > > > Maybe I get it. You want to use the new features as a carrot to > > > > > force drivers to implement DMA? You suspect they will ignore the > > > > > spec requirement just because things seem to work? > > > > > > > > > Right because it is not a must normative. > > > Well SHOULD also does not mean "ok to just ignore". > > > > > > This word, or the adjective "RECOMMENDED", mean that there > > > may exist valid reasons in particular circumstances to ignore a > > > particular item, but the full implications must be understood and > > > carefully weighed before choosing a different course. > > > > > RECOMMENDED and SHOULD forces the device to support MMIO, which is not good. > > So rather a good design is device tells the starting offset for the extended config space. > > And extended config space MUST be accessed using a DMA. > > With this sw can have infinite size MMIO and hw device forces DMA based on its implementation of where to start DMA from. > > This also gives the ability to maintain current config as MMIO for backward compatibility. > > > > > > > > There's some logic here, for sure. you just might be right. > > > > > > > > > > However, surely we can discuss this small tweak in 1.4 timeframe? > > > > Sure, if we prefer the DMA approach I don't have a problem in adding > > > temporary one field to config space. > > > > I propose to add a line to the spec " Device Configuration Space" > > > > section, something like, > > > > > > > > Note: Any new device configuration space fields additional MUST consider > > > accessing such fields via a DMA interface. > > > > And this will guide the new patches of what to do instead of last moment > > > rush. > > > > > > Yea, except again I'd probably make it a SHOULD: e.g. I can see how switching to > > > MMIO might be an option for qemu helping us debug DMA issues. > > > > > There are too many queues whose debugging is needed and MMIO likely not the way to debug. > > > The time to discuss this detail would be around when proposal for the DMA > > > access to config space is on list though: I feel this SHOULD vs MUST is a small > > > enough detail. > > > > > From implementation POV it is certainly critical and good step forward to optimize virtio interface. > > > Going back to inner hash. If we move supported_tunnels back to config space, > > > do you feel we still need GET or just drop it? I note we do not have GET for > > > either hash or rss config. > > > > > For hash and rss config, debugging is missing. :) > > Yes, we can drop the GET after switching supported_tunnels to struct virtio_net_hash_config. > > Great! Glad to hear this! > > > > And if we no longer have GET is there still a reason for a separate command as > > > opposed to a field in virtio_net_hash_config? > > > I know this was done in v11 but there it was misaligned. > > > We went with a command because we needed it for supported_tunnels but > > > now that is no longer the case and there are reserved words in > > > virtio_net_hash_config ... > > > > > > Let me know how you feel it about that, not critical for me. > > struct virtio_net_hash_config reserved is fine. > > +1. > > Inner header hash is orthogonal to RSS, and it's fine to have its own > structure and commands. > There is no need to send additional RSS fields when we configure inner > header hash. > > Thanks. Not RSS, hash calculations. It's not critical, but I note that practically you said you will enable this with symmetric hash so it makes sense to me to send this in the same command with the key. Not critical though if there's opposition. -- MST --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org