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 9FC7AC7EE26 for ; Wed, 3 May 2023 10:16:25 +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 92887FD57F for ; Wed, 3 May 2023 10:16:23 +0000 (UTC) Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id 424749866C4 for ; Wed, 3 May 2023 10:16:23 +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 2FCD1986586; Wed, 3 May 2023 10:16:23 +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 1E774986734 for ; Wed, 3 May 2023 10:16:23 +0000 (UTC) X-Virus-Scanned: amavisd-new at kavi.com X-MC-Unique: ib4eqJR3PfWElHGAHdOY2Q-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1683108979; x=1685700979; 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=gnUuOWxd50wNIr2us72kSXUu3mOWQAJOG9u8MSlfqZo=; b=LAOvDUsLHb2z5nqmom1kQqfpo4m1Qe1JssdRlCl7X2AxcTWTakr+VYuS8+05BZ1CaH UtbxBEYbFJKBnWJkonLer3Vixz+wyhEOSOkFV2gHWROBXRI4bXnMcpAMsMXEMelieXJg a/IcXslAMlZ7fLNeVF1HmMJ+cYHKV7E6WMYmpmqgpqJwFEzcqPNNP20mvDTgIU7uD1Os KUYp2PokH6bf19gZ4IOX+QnzdOFpMw6doUZYuUjwIeK4iBHpIVo6M299zOjwD8n3CxJj tAHLCmViDIzpZ9YLRUZPEnXZzGKafkKepw7NQizmuSi47zJSN5L7zFcXy1y44qDy90KH 5n0A== X-Gm-Message-State: AC+VfDzSeknUf3Xfaq0j0JDKG4bQ2qybEDOATn/QXffuU7nN3QYHEM/0 wX1rkam8GAE9qfanQOw1nlAx1TeLp5LDzrb+5MD67hBY5Gj1Ogd5xXLeUDLjj46DLqfhCpenaxp gM6ZxmNcElcrRVy7SdpeE9KpCmjxt X-Received: by 2002:a1c:f717:0:b0:3f1:7972:429d with SMTP id v23-20020a1cf717000000b003f17972429dmr13715802wmh.18.1683108978888; Wed, 03 May 2023 03:16:18 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ5S2OBAxG7FhqVzhhIF1RvVUpTGul3G8zAUz5Z7yfpsEqVPLtkIeNbgkx6R+JsMGiFdZzjQXg== X-Received: by 2002:a1c:f717:0:b0:3f1:7972:429d with SMTP id v23-20020a1cf717000000b003f17972429dmr13715786wmh.18.1683108978551; Wed, 03 May 2023 03:16:18 -0700 (PDT) Date: Wed, 3 May 2023 06:16:13 -0400 From: "Michael S. Tsirkin" To: Parav Pandit Cc: virtio-dev@lists.oasis-open.org, cohuck@redhat.com, david.edmondson@oracle.com, sburla@marvell.com, jasowang@redhat.com, virtio-comment@lists.oasis-open.org, shahafs@nvidia.com Message-ID: <20230503060538-mutt-send-email-mst@kernel.org> References: <20230503032659.530330-1-parav@nvidia.com> MIME-Version: 1.0 In-Reply-To: <20230503032659.530330-1-parav@nvidia.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: [PATCH v1 0/2] transport-pci: Introduce legacy registers access using AQ On Wed, May 03, 2023 at 06:26:57AM +0300, Parav Pandit wrote: > This patch introduces legacy registers access commands for the owner > group member PCI PF to access the legacy registers of the member VFs. > > If in future any SIOV devices to support legacy registers, they > can be easily supported using same commands by using the group > member identifiers of the future SIOV devices. Absolutely, but maybe we should not create work for this case by repeating PF/VF terminology everywhere? > More details as overview, motivation, use case are further described > below. > > Patch summary: > -------------- > patch-1 adds administrative virtuqueue commands > patch-2 adds its conformance section > > This short series is on top of [1]. > It uses the newly introduced administrative virtqueue facility with 3 new > opcodes and uses the existing virtio_admin_cmd. > > It is expected to go another rebase once v13 for [1] is rolled out and merged. > > [1] https://lore.kernel.org/virtio-comment/cover.1682354275.git.mst@redhat.com/T/#t > > Usecase: > -------- > 1. A hypervisor/system needs to provide transitional > virtio devices to the guest VM at scale of thousands, > typically, one to eight devices per VM. > > 2. A hypervisor/system needs to provide such devices using a > vendor agnostic driver in the hypervisor system. > > 3. A hypervisor system prefers to have single stack regardless of > virtio device type (net/blk) and be future compatible with a > single vfio stack using SR-IOV or other scalable device > virtualization technology to map PCI devices to the guest VM. > (as transitional or otherwise) > > Motivation/Background: > ---------------------- > The existing virtio transitional PCI device is missing support for > PCI SR-IOV based devices. Currently it does not work beyond > PCI PF, or as software emulated device in reality. Currently it > has below cited system level limitations: > > [a] PCIe spec citation: > VFs do not support I/O Space and thus VF BARs shall not indicate I/O Space. > > [b] cpu arch citiation: > Intel 64 and IA-32 Architectures Software Developer’s Manual: > The processor’s I/O address space is separate and distinct from > the physical-memory address space. The I/O address space consists > of 64K individually addressable 8-bit I/O ports, numbered 0 through FFFFH. > > [c] PCIe spec citation: > If a bridge implements an I/O address range,...I/O address range will be > aligned to a 4 KB boundary. > > Above usecase requirements can be solved by PCI PF group owner enabling > the access to its group member PCI VFs legacy registers using an admin > virtqueue of the group owner PCI PF. > > Software usage example: > ----------------------- > The most common way to use and map to the guest VM is by > using vfio driver framework in Linux kernel. > > +----------------------+ > |pci_dev_id = 0x100X | > +---------------|pci_rev_id = 0x0 |-----+ > |vfio device |BAR0 = I/O region | | > | |Other attributes | | > | +----------------------+ | > | | > + +--------------+ +-----------------+ | > | |I/O BAR to AQ | | Other vfio | | > | |rd/wr mapper | | functionalities | | > | +--------------+ +-----------------+ | > | | > +------+-------------------------+-----------+ > | | > +----+------------+ +----+------------+ > | +-----+ | | PCI VF device A | > | | AQ |-------------+---->+-------------+ | > | +-----+ | | | | legacy regs | | > | PCI PF device | | | +-------------+ | > +-----------------+ | +-----------------+ > | > | +----+------------+ > | | PCI VF device N | > +---->+-------------+ | > | | legacy regs | | > | +-------------+ | > +-----------------+ > > 2. Virtio pci driver to bind to the listed device id and > use it as native device in the host. > > 3. Use it in a light weight hypervisor to run bare-metal OS. > > Please review. > > Fixes: https://github.com/oasis-tcs/virtio-spec/issues/167 > Signed-off-by: Parav Pandit I don't see an overview here though. > --- > changelog: > v0->v1: > - addressed comments, suggesetions and ideas from Michael Tsirkin and Jason Wang > - far more simpler design than MMR access > - removed complexities of MMR device ids > - removed complexities of MMR registers and extended capabilities > - dropped adding new extended capabilities because if if they are > added, a pci device still needs to have existing capabilities > in the legacy configuration space and hypervisor driver do not > need to access them > > > Parav Pandit (2): > transport-pci: Introduce legacy registers access commands > transport-pci: Add legacy register access conformance section > > admin.tex | 5 +- > conformance.tex | 2 + > transport-pci-vf-regs.tex | 115 ++++++++++++++++++++++++++++++++++++++ > transport-pci.tex | 2 + > 4 files changed, 123 insertions(+), 1 deletion(-) > create mode 100644 transport-pci-vf-regs.tex > > -- > 2.26.2 --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org