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 8AF48C7619A for ; Wed, 12 Apr 2023 04:55:58 +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 01CD829FCC for ; Wed, 12 Apr 2023 04:55:58 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id F140F9865B3 for ; Wed, 12 Apr 2023 04:55:57 +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 E656F98650E; Wed, 12 Apr 2023 04:55:57 +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 D5405986509 for ; Wed, 12 Apr 2023 04:55:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: hGNqWtBYM7iIq3HXi_R6Mw-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1681275351; x=1683867351; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=filE9Lqtnzk1DU5Kt4NqqjI1ImBhYxDbzsA2JLSiIkc=; b=6cPB4viLNJ66k0CqWjujIBP2KkpTtPI5/dUT3rlpCrIgGzQcnKzjnQG9i4J5RzFsxc bfYXspL0RwyZF4U2CsSJnidn2ROUv8vE9mHXWXW78jY2xsYJr9pXj7NAm4UZ+5y7Lgma a+ttMZ46EDF9MdviNIySZh5VGCSb3knpCjUJpE8kE0yS0yShySR22T6b4fq/aQ8WAyrn C+wxycLZQJaLIOliySEbOrbADD3n4eclk5vEtyIPsofTXSP/3FXZvgigcXB2AOZ1KVcg 024VwYvjXS21C9orvQqihUzyhTAK7P2bc0C1UAXjxGiKkO6iNejtAUtuxcrZuZFmMPu6 2zcw== X-Gm-Message-State: AAQBX9drNhszObE8fMAts8b6oAqrbulRsEWxdUDTkwrFcV558PbLgL4o gxW0yjifX6C2RzCk//28rxoLTamkGZ/sNR0CeV42XMgAxJ9TBiDPAkVm0YAFDjLbaiCngo+SLlv 6f9psrFMf/2lSOm0U3FMk59hNrK9ETJwzsfeKLDf/wB5j X-Received: by 2002:ac8:5c85:0:b0:3bf:b9d9:675f with SMTP id r5-20020ac85c85000000b003bfb9d9675fmr6283595qta.10.1681275351429; Tue, 11 Apr 2023 21:55:51 -0700 (PDT) X-Google-Smtp-Source: AKy350YgY3Fh4OE8b4SJvBZOk9J1zZ5OHAy4uJy0qdTmas7wyg6RtUE7UEe6xjc9N5o5yfe6eQmwiv7kcLHA+OlzQf4= X-Received: by 2002:ac8:5c85:0:b0:3bf:b9d9:675f with SMTP id r5-20020ac85c85000000b003bfb9d9675fmr6283587qta.10.1681275351212; Tue, 11 Apr 2023 21:55:51 -0700 (PDT) MIME-Version: 1.0 References: <20230330225834.506969-1-parav@nvidia.com> <20230330225834.506969-9-parav@nvidia.com> <307a9f8f-6184-0403-97ab-1b1c16d4fd3c@nvidia.com> <20230412002017-mutt-send-email-mst@kernel.org> In-Reply-To: <20230412002017-mutt-send-email-mst@kernel.org> From: Jason Wang Date: Wed, 12 Apr 2023 12:55:39 +0800 Message-ID: To: "Michael S. Tsirkin" Cc: Parav Pandit , "virtio-dev@lists.oasis-open.org" , "cohuck@redhat.com" , "virtio-comment@lists.oasis-open.org" , Shahaf Shuler , Satananda Burla X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: Re: [virtio-dev] [PATCH 08/11] transport-pci: Introduce virtio extended capability On Wed, Apr 12, 2023 at 12:21=E2=80=AFPM Michael S. Tsirkin wrote: > > On Wed, Apr 12, 2023 at 12:04:45PM +0800, Jason Wang wrote: > > On Wed, Apr 12, 2023 at 3:01=E2=80=AFAM Parav Pandit = wrote: > > > > > > > > > > From: virtio-dev@lists.oasis-open.org On > > > > Behalf Of Jason Wang > > > > Sent: Monday, April 10, 2023 11:29 PM > > > > > > > > However, it is not backward compatible, if the device place them = in > > > > > extended capability, it will not work. > > > > > > > > > > > > > It is kind of intended since it is only used for new PCI-E features= : > > > > > > > New fields in new extended pci cap area is fine. > > > Migrating old fields to be present in the new extended pci cap, is no= t your intention. Right? > > > > Right, but what I want to say is, such migration may cause unnecessary > > problems. And I don't see why it is a must for your legacy MMIO bar > > proposal. > > > > > > > > > " > > > > +The location of the virtio structures that depend on the PCI Expre= ss > > > > +capability are specified using a vendor-specific extended capabili= ties > > > > +on the extended capabilities list in PCI Express extended configur= ation > > > > +space of the device. > > > > " > > > > > > > > > To make it backward compatible, a device needs to expose existing > > > > > structure in legacy area. And extended structure for same capabil= ity > > > > > in extended pci capability region. > > > > > > > > > > In other words, it will have to be a both places. > > > > > > > > Then we will run out of config space again? > > > No. > > > Only currently defined caps to be placed in two places. > > > > What's the advantage of doing this? > > > > New drivers should provide backward compatibility so they must scan the= pci cap. > > No, they can start with express cap. Finding one they can skip > the old cap completely. Then the driver can't work on the old device. Thanks > > > The Old driver can only scan the pci cap. > > > > > New fields don=E2=80=99t need to be placed in PCI cap, because no dri= ver is looking there. > > > > It would be much more simple if we forbid placing new fields in the > > PCI cap, it is already out of space. > > > > Thanks > > > > > > > > We probably already discussed this in previous email by now. > > > > > > > Otherwise we need to deal with the > > > > case when existing structures were only placed at extended capabili= ty. Michael > > > > suggest to add a new feature, but the driver may not negotiate the = feature > > > > which requires more thought. > > > > > > > Not sure I understand feature bit. > > > PCI transport fields existence is usually not dependent on upper laye= r protocol. > > > > > > > > We may need it even sooner than this because the AQ patch is expa= nding > > > > > the structure located in legacy area. > > > > > > > > Just to make sure I understand this, assuming we have adminq, any r= eason a > > > > dedicated pcie ext cap is required? > > > > > > > No. it was my short sight. I responded right after above text that AQ= doesn=E2=80=99t need cap extension. > --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org 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 8DBCAC7619A for ; Wed, 12 Apr 2023 04:55:54 +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 E8D272AC49 for ; Wed, 12 Apr 2023 04:55:53 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id DDC4B98651C for ; Wed, 12 Apr 2023 04:55:53 +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 D5CE198650F; Wed, 12 Apr 2023 04:55:53 +0000 (UTC) Mailing-List: contact virtio-comment-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 C360598650E for ; Wed, 12 Apr 2023 04:55:53 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: 2yfTK4EJNLanp46z5F-z_A-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1681275351; x=1683867351; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=filE9Lqtnzk1DU5Kt4NqqjI1ImBhYxDbzsA2JLSiIkc=; b=kRPdPVtvwC1gqtNblUSJR8UoQ0NLV7cWa6o654DOIJYnaysTRqWuor8bSUZqkPPdIV BUIfSCZYhlBro5Xkcj+rBbfOjnmRXB6W7obmVvEQ7aI5NPH+mr50FE0qh3ojc9wZ5wrF kYz+kt8S/H/n0uQPmnTFCZj3kS4oP1VSTtUFhw9iwZoTNkFS6XDthODwATOY+OqGmf8+ Rbq6KvnwT/wIvn85nBdmAxJcePe1zjh1avy/adtliG3/abqE8fNqKJo9GLaVVXNghOyx 99XxssMif5PsuSR4l8nUfOgUZAnPSnDZKCDW7OiTl5BPc1Ton+fB8VHWXJ1XI45abp6T kxSQ== X-Gm-Message-State: AAQBX9dWlpN0Sc27w1RjAk754SLrE/CaRSKGs0Uh08wgwjR4qIN4b5dw T84gCvb2/npVhgQNFOJuc1XEh1p9utd0AvfxHYZjiPSRVIEg6pJ5P4t/AzEYwKWWyVId8zVSqka ktyesOwDZlqcLx2MvIFjHhYZHi/fhVcRYwnvfc67mmPMIyIXt5w== X-Received: by 2002:ac8:5c85:0:b0:3bf:b9d9:675f with SMTP id r5-20020ac85c85000000b003bfb9d9675fmr6283594qta.10.1681275351429; Tue, 11 Apr 2023 21:55:51 -0700 (PDT) X-Google-Smtp-Source: AKy350YgY3Fh4OE8b4SJvBZOk9J1zZ5OHAy4uJy0qdTmas7wyg6RtUE7UEe6xjc9N5o5yfe6eQmwiv7kcLHA+OlzQf4= X-Received: by 2002:ac8:5c85:0:b0:3bf:b9d9:675f with SMTP id r5-20020ac85c85000000b003bfb9d9675fmr6283587qta.10.1681275351212; Tue, 11 Apr 2023 21:55:51 -0700 (PDT) MIME-Version: 1.0 References: <20230330225834.506969-1-parav@nvidia.com> <20230330225834.506969-9-parav@nvidia.com> <307a9f8f-6184-0403-97ab-1b1c16d4fd3c@nvidia.com> <20230412002017-mutt-send-email-mst@kernel.org> In-Reply-To: <20230412002017-mutt-send-email-mst@kernel.org> From: Jason Wang Date: Wed, 12 Apr 2023 12:55:39 +0800 Message-ID: To: "Michael S. Tsirkin" Cc: Parav Pandit , "virtio-dev@lists.oasis-open.org" , "cohuck@redhat.com" , "virtio-comment@lists.oasis-open.org" , Shahaf Shuler , Satananda Burla X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Subject: [virtio-comment] Re: [virtio-dev] [PATCH 08/11] transport-pci: Introduce virtio extended capability On Wed, Apr 12, 2023 at 12:21=E2=80=AFPM Michael S. Tsirkin wrote: > > On Wed, Apr 12, 2023 at 12:04:45PM +0800, Jason Wang wrote: > > On Wed, Apr 12, 2023 at 3:01=E2=80=AFAM Parav Pandit = wrote: > > > > > > > > > > From: virtio-dev@lists.oasis-open.org On > > > > Behalf Of Jason Wang > > > > Sent: Monday, April 10, 2023 11:29 PM > > > > > > > > However, it is not backward compatible, if the device place them = in > > > > > extended capability, it will not work. > > > > > > > > > > > > > It is kind of intended since it is only used for new PCI-E features= : > > > > > > > New fields in new extended pci cap area is fine. > > > Migrating old fields to be present in the new extended pci cap, is no= t your intention. Right? > > > > Right, but what I want to say is, such migration may cause unnecessary > > problems. And I don't see why it is a must for your legacy MMIO bar > > proposal. > > > > > > > > > " > > > > +The location of the virtio structures that depend on the PCI Expre= ss > > > > +capability are specified using a vendor-specific extended capabili= ties > > > > +on the extended capabilities list in PCI Express extended configur= ation > > > > +space of the device. > > > > " > > > > > > > > > To make it backward compatible, a device needs to expose existing > > > > > structure in legacy area. And extended structure for same capabil= ity > > > > > in extended pci capability region. > > > > > > > > > > In other words, it will have to be a both places. > > > > > > > > Then we will run out of config space again? > > > No. > > > Only currently defined caps to be placed in two places. > > > > What's the advantage of doing this? > > > > New drivers should provide backward compatibility so they must scan the= pci cap. > > No, they can start with express cap. Finding one they can skip > the old cap completely. Then the driver can't work on the old device. Thanks > > > The Old driver can only scan the pci cap. > > > > > New fields don=E2=80=99t need to be placed in PCI cap, because no dri= ver is looking there. > > > > It would be much more simple if we forbid placing new fields in the > > PCI cap, it is already out of space. > > > > Thanks > > > > > > > > We probably already discussed this in previous email by now. > > > > > > > Otherwise we need to deal with the > > > > case when existing structures were only placed at extended capabili= ty. Michael > > > > suggest to add a new feature, but the driver may not negotiate the = feature > > > > which requires more thought. > > > > > > > Not sure I understand feature bit. > > > PCI transport fields existence is usually not dependent on upper laye= r protocol. > > > > > > > > We may need it even sooner than this because the AQ patch is expa= nding > > > > > the structure located in legacy area. > > > > > > > > Just to make sure I understand this, assuming we have adminq, any r= eason a > > > > dedicated pcie ext cap is required? > > > > > > > No. it was my short sight. I responded right after above text that AQ= doesn=E2=80=99t need cap extension. > This publicly archived list offers a means to provide input to the=0D OASIS Virtual I/O Device (VIRTIO) TC.=0D =0D In order to verify user consent to the Feedback License terms and=0D to minimize spam in the list archive, subscription is required=0D before posting.=0D =0D Subscribe: virtio-comment-subscribe@lists.oasis-open.org=0D Unsubscribe: virtio-comment-unsubscribe@lists.oasis-open.org=0D List help: virtio-comment-help@lists.oasis-open.org=0D List archive: https://lists.oasis-open.org/archives/virtio-comment/=0D Feedback License: https://www.oasis-open.org/who/ipr/feedback_license.pdf=0D List Guidelines: https://www.oasis-open.org/policies-guidelines/mailing-lists=0D Committee: https://www.oasis-open.org/committees/virtio/=0D Join OASIS: https://www.oasis-open.org/join/