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 976BAC7EE24 for ; Mon, 15 May 2023 07:13:36 +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 D5B89C624C for ; Mon, 15 May 2023 07:13:35 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id C37F2986511 for ; Mon, 15 May 2023 07:13:35 +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 B6DEB986348; Mon, 15 May 2023 07:13:35 +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 A3C2D98636A for ; Mon, 15 May 2023 07:13:33 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: qtpkEQDKOGu7k9rk3t0xxQ-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1684134810; x=1686726810; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=pLETnC/SDkvbm3TD93APrMhXuCURCpBqP3MGBL26f8g=; b=NdgXYfq/gNHMIDNyzQ5z2NUXkJtTNPd8NNoIbR5hXsbvdmj78Xl/hd3M7UrrJ0n9Ln st4Xm+LaLrXGRwDxegkSjO/MAqzsuYEu2N8JFjWhTJITraVikXqS8NZQcvhUGIDWJUqw UepHza/D/3/D8aE6fUhctt1gw6FIpaguHcLuD9jbQDGqiLSqswQzB+sGRKiMivWIte6d lKxUlrQPDqDQqu/j+noFWEnSKJtMrVCNiEtZWyHDAghgH7tePnlBk4KyKNwxtNIDW7TC XKzMuVfxEAfcSMvgng/N/I8cGlKK2u31UVnbEXiwf79qXS21pXKFC/ooQHKNtvry3VSo SEEw== X-Gm-Message-State: AC+VfDzg4ZfGfnFMkzFpKP8rG6rTpi9B3XUmUO+D5EMHykY3IdhU50l1 9v4paAyFnZqw+/ytIOQo1xqf1FAbKzwIm4QFhQo0r0VJ86GuOyfAVkrll8kxTpdGcZzKfKTaXao K7nP9/Aaz0uC8ONHaS6oW8O4D3kFd X-Received: by 2002:a05:6a00:2346:b0:63f:2f00:c6d with SMTP id j6-20020a056a00234600b0063f2f000c6dmr43896152pfj.2.1684134810528; Mon, 15 May 2023 00:13:30 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ7CXlsXytTrSpu08N4Kq7vdEaVM38mm+lnLnEK/9m3eVDv4vK2/l0tXUsy8PMlkX7iETH5ubQ== X-Received: by 2002:a05:6a00:2346:b0:63f:2f00:c6d with SMTP id j6-20020a056a00234600b0063f2f000c6dmr43896135pfj.2.1684134810168; Mon, 15 May 2023 00:13:30 -0700 (PDT) Message-ID: <4f7ad7f3-64bd-cd77-1a8a-30e93947ea30@redhat.com> Date: Mon, 15 May 2023 15:13:23 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.10.0 To: "Michael S. Tsirkin" Cc: Parav Pandit , virtio-dev@lists.oasis-open.org, cohuck@redhat.com, david.edmondson@oracle.com, sburla@marvell.com, yishaih@nvidia.com, maorg@nvidia.com, virtio-comment@lists.oasis-open.org, shahafs@nvidia.com References: <20230506000135.628899-1-parav@nvidia.com> <20230507093959-mutt-send-email-mst@kernel.org> <20230510014534-mutt-send-email-mst@kernel.org> <20230510033812-mutt-send-email-mst@kernel.org> <20230511085205-mutt-send-email-mst@kernel.org> From: Jason Wang In-Reply-To: <20230511085205-mutt-send-email-mst@kernel.org> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Subject: [virtio-dev] Re: [PATCH v2 0/2] transport-pci: Introduce legacy registers access using AQ 在 2023/5/11 20:54, Michael S. Tsirkin 写道: > On Thu, May 11, 2023 at 03:04:40PM +0800, Jason Wang wrote: >> On Wed, May 10, 2023 at 3:43 PM Michael S. Tsirkin wrote: >>> On Wed, May 10, 2023 at 03:01:25PM +0800, Jason Wang wrote: >>>> On Wed, May 10, 2023 at 2:05 PM Michael S. Tsirkin wrote: >>>>> On Mon, May 08, 2023 at 10:23:39AM +0800, Jason Wang wrote: >>>>>>> I thought so too originally. Unfortunately I now think that no, legacy is not >>>>>>> going to be a byproduct of transport virtqueue for modern - >>>>>>> it is different enough that it needs dedicated commands. >>>>>> If you mean the transport virtqueue, I think some dedicated commands >>>>>> for legacy are needed. Then it would be a transport that supports >>>>>> transitional devices. It would be much better than having commands for >>>>>> a partial transport like this patch did. >>>>> OK I am beginning to get what you are saying. So your criticism is >>>>> this: what if device supports vq transport for modern, and we want to >>>>> build a transitional device on top. how will that look. yes? >>>> Yes. I think it needs to be done through the transport virtqueue >>>> otherwise the transport is not self-contained. >>> I mean, any feature can be done over transport vq. >>> >>> But there is value in adding legacy commands to an otherwise >>> modern device without reworking it completely to >>> switch to a different transport. >> There's probably no need for a rework since legacy is not complicated. >> More below. >> >>> >>>>> A reasonable thing to include at least in the commit log. Parav? >>>>> >>>>> You are also asking what if the device uses transport vq, >>>>> and we want transitional on top of that. >>>>> It's a fair question but I don't exactly get why would >>>>> this legacy support feature be wanted for the vq transport >>>>> and not for other transports. >>>> Not sure I get the question, but all the existing transport support >>>> legacy, if we want to have another, should the legacy support be a >>>> must or not? >>> This specific proposal is for tunneling legacy over admin vq. >>> It can live alongside a normal modern VF, with hypervisor >>> combining these to create a transitional device. >> Exactly, but what I meant here is >> >> If we decide to use the admin vq, is there any good reason to tie it >> to PCI if we don't want to tunneling PCI over adminq? >> >> Why not simply invent individual commands to access legacy facilities >> like commands to access like what transport virtqueue did for modern >> device?: >> >> 1) device features >> 2) driver features >> 3) queue address >> 4) queue size >> 5) queue select >> 6) queue notify >> 7) device status >> 8) ISR status >> 9) config msix >> 10) queue msix >> 11) device configuration space >> >> It focuses on the facilities instead of transport specific details >> like registers (we don't even need legacy registers in this case), I >> gives more deterministic behavior so we don't need to care about the >> cross registers read/write. > This needs thought, it is definitely more work. Effort that could be > maybe spent on new features. What is the motivation > here? supporting legacy mmio guests? Probably. It tries to make legacy transport independent, and it's the way that how transport virtqueue want to be. Thanks --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org