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 9D58EEB64DB for ; Mon, 19 Jun 2023 17:57:50 +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 ED7B9C623F for ; Mon, 19 Jun 2023 17:57:49 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id E55949864BD for ; Mon, 19 Jun 2023 17:57:49 +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 D9B829863BD; Mon, 19 Jun 2023 17:57:49 +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 C6219986428 for ; Mon, 19 Jun 2023 17:57:47 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: YCMiSPG7MiGhHGOKR-EIfg-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1687197462; x=1689789462; h=in-reply-to: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=OwHZZ7wwhMQA3lKajQTdq1PYdZYpPPfzoNjCpqwrcic=; b=E2GbmtsHYOFOEHGI1duAoRQS9LjMSNK0hLIt80H2UtHLIVQ9WSbsTwMZHo8V0ncg5o 6FyBSkKGTBlzfWxeCt4qRjcDWYcKool/zSc+W1mftg5aJaSDhmznEWWNmd1AoRLbql+Y H6/t1ntUs1PqWtEQAnkD1HSTIxG8NwND61/YqBZD2wCTXGNjv5bhhsoihY0jXaDfiBeJ 6IBt4Z8E9u4AmzvYIpWxaDedFrer6jaMyFe84vah+JK6dvqauyCmW3DBkn1KfZQ6uudc xEcH9aByZMsVbnGkQEU443a45nnNIxDn5uI1B3+L+3ypbarOzbMwOoAIYqjWrNQpmZe8 g4rQ== X-Gm-Message-State: AC+VfDzH0OUwXZFErKFIeKbl6Fng39jKw8nnWh6F/N0Py1kSv8FagAgh MV5j9TqY8ioA+Z88GzKQkZu02fFSTE9WttHs0Gr+hwLbs+Ud58oOz0/wHyxjjVZGeCWIAzkpIVx 1u4swXsZK1kAlQ7/bIUmDFaJVwFFc X-Received: by 2002:a5d:68d0:0:b0:30f:c008:a921 with SMTP id p16-20020a5d68d0000000b0030fc008a921mr8285212wrw.17.1687197462403; Mon, 19 Jun 2023 10:57:42 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ4JGu7epeNB7k0q3Fep7rLSWUkEREGHXR1ZOK7aQANtnNp1YlBrDqbh/35nvUyWh4MGPdxZxA== X-Received: by 2002:a5d:68d0:0:b0:30f:c008:a921 with SMTP id p16-20020a5d68d0000000b0030fc008a921mr8285197wrw.17.1687197462060; Mon, 19 Jun 2023 10:57:42 -0700 (PDT) Date: Mon, 19 Jun 2023 13:57:37 -0400 From: "Michael S. Tsirkin" To: Parav Pandit Cc: "virtio-comment@lists.oasis-open.org" , "cohuck@redhat.com" , "david.edmondson@oracle.com" , "virtio-dev@lists.oasis-open.org" , "sburla@marvell.com" , "jasowang@redhat.com" , Yishai Hadas , Maor Gottlieb , Shahaf Shuler Message-ID: <20230619134649-mutt-send-email-mst@kernel.org> References: <20230613173015.1244486-1-parav@nvidia.com> <20230613173015.1244486-5-parav@nvidia.com> <20230619122836-mutt-send-email-mst@kernel.org> <20230619131115-mutt-send-email-mst@kernel.org> <20230619133322-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Subject: [virtio-dev] Re: [PATCH v6 4/4] transport-pci: Introduce group legacy group member config region access On Mon, Jun 19, 2023 at 05:45:17PM +0000, Parav Pandit wrote: > > > > From: Michael S. Tsirkin > > Sent: Monday, June 19, 2023 1:38 PM > > > > > If we can't just make it come for free then maybe > > > > VIRTIO_PCI_CAP_LEGACY_NOTIFY_CFG is better, we can just list the > > > > number in the common section and then link to the description in the new > > section. > > > > > > > How is it better? It requires burning more bytes. > > > Is it better because it is self contained? > > > > Mostly yes. But it also adds a bit more flexibility, right? > > I thought avoiding touching transport-pci is worth less flexibility but if we can't > > avoid that... > > > That flexibility is better gained via AQ instead of introducing new extended capability on the VF. > > > > > > > I also feel we want ability to have such a capability in the owner too. > > > > Would prefer including it now though I guess we can add it as an extension. > > > > > > Re-opening the past discussion.. amazing. :) > > > > OK fair enough.. I guess both of us are not 100% happy but it's a compromize > > for now. And maybe we'll add one of AQ and / or PF cap down the road. > > > > > Why? How is it different and better than querying over AQ? > > > > Wait a second let me clarify. I am talking about notification in the PCI BAR of the > > PF. *Not* offset in PF capability but in the VF BAR. > > > Ok. question remains the same, why not discover such notification capability it over the AQ command? > AQ command on the PF is self-contained and extendible without baking things in very low level hw centric pci capabilities, which are hard to get rid of it. I worry about systems where there's value in having VF driver map memory without talking to PF driver. Current VF capability is kind of ok I guess ... If you want admin command to query then it would need to map in PF memory. I understand two concerns with this: - you worry that this forces ordering requirements - it's true and I don't know of a good fix. So if possible use VF BAR by preference? - you worry about wasting physical memory space this we can fix by sticking VF# in the kick. As an alternative, if we can make the new command able to communicate offset in PCI BAR or in VF BAR or both then I think that's also an acceptable compromize: drivers that have trouble mapping VF BAR after querying PF can just map PF BAR. WDYT? > > > > > I see the AQ is better than group owner and group member specific cap. > > --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org