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Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [RFC 0/1] virtio-net: add support for SR-IOV emulation Content-Language: en-US To: Jason Wang Cc: qemu-devel@nongnu.org, mst@redhat.com, akihiko.odaki@daynix.com, yvugenfi@redhat.com, ybendito@redhat.com, mapfelba@redhat.com, marcel@redhat.com, ghammer@redhat.com, mdean@redhat.com References: <1689731808-3009-1-git-send-email-yui.washidu@gmail.com> From: Yui Washizu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2001:4860:4864:20::29; envelope-from=yui.washidu@gmail.com; helo=mail-oa1-x29.google.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, NICE_REPLY_A=-0.091, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2023/07/24 15:58, Jason Wang wrote: > On Mon, Jul 24, 2023 at 10:32 AM Yui Washizu wrote: >> >> On 2023/07/20 11:20, Jason Wang wrote: >>> On Wed, Jul 19, 2023 at 9:59 AM Yui Washizu wrote: >>>> This patch series is the first step towards enabling >>>> hardware offloading of the L2 packet switching feature on virtio-net device to host machine. >>>> We are considering that this hardware offloading enables >>>> the use of high-performance networks in virtual infrastructures, >>>> such as container infrastructures on VMs. >>>> >>>> To enable L2 packet switching by SR-IOV VFs, we are considering the following: >>>> - making the guest recognize virtio-net devices as SR-IOV PF devices >>>> (archived with this patch series) >>>> - allowing virtio-net devices to connect SR-IOV VFs to the backend networks, >>>> leaving the L2 packet switching feature to the management layer like libvirt >>> Could you please show the qemu command line you want to propose here? >> >> I am considering how to specify the properties of VFs to connect SR-IOV >> VFs to the backend networks. >> >> >> For example: >> >> >> qemu-system-x86_64 -device >> pcie-root-port,port=8,chassis=8,id=pci.8,bus=pcie.0,multifunction=on >> -netdev tap,id=hostnet0,vhost=on >> -netdev tap,id=vfnet1,vhost=on # backend network for >> SR-IOV VF 1 >> -netdev tap,id=vfnet2,vhost=on # backend network for >> SR-IOV VF 2 >> -device >> virtio-net-pci,netdev=hostnet0,sriov_max_vfs=2,sriov_netdev=vfnet1:vfnet2,... >> >> >> In this example, we can specify multiple backend networks to the VFs >> by adding "sriov_netdev" and separating them with ":". > This seems what is in my mind as well, more below > >> Additionally, when passing properties like "rx_queue_size" to VFs, we >> can utilize new properties, >> such as "sriov_rx_queue_size_per_vfs," to ensure that the same value is >> passed to all VFs. > Or we can introduce new device like: > > -netdev tap,id=hn0 \ > -device virtio-net-pci,netdev=hn0,id=vnet_pf \ > -netdev tap,netdev=hn1 \ > -device virtio-net-pci-vf,netdev=hn1,id=vf0,pf=vnet_pf,rx_queue_size=XYZ ... \ > > This allows us to reuse the codes for configuring vf parameters. Yes, I was also considering this method was one of the option. I was concerned that the implementation for it might be different from other devices specified by the "-device" option because VF devices are created when the guest creates VFs from PFs, not when the guest starts, and the implementation may be complicated. So I dropped the idea then. However, I think it is a cleaner way for specifying VFs than my suggested one. I will further consider whether the implementation will be really difficult or not. Thank you. > But > note that rx_queue_size doesn't make too much sense to vhost-vDPA, as > qemu can perform nothing more than a simple sanity test. > > Thanks > >> I'm still considering about how to specify it, so please give me any >> comments if you have any. >> >> >>>> - This makes hardware offloading of L2 packet switching possible. >>>> For example, when using vDPA devices, it allows the guest >>>> to utilize SR-IOV NIC embedded switch of hosts. >>> This would be interesting. >>> >>> Thanks >>> >>>> This patch series aims to enable SR-IOV emulation on virtio-net devices. >>>> With this series, the guest can identify the virtio-net device as an SR-IOV PF device. >>>> The newly added property 'sriov_max_vfs' allows us to enable the SR-IOV feature >>>> on the virtio-net device. >>>> Currently, we are unable to specify the properties of a VF created from the guest. >>>> The properties are set to their default values. >>>> In the future, we plan to allow users to set the properties. >>>> >>>> qemu-system-x86_64 --device virtio-net,sriov_max_vfs= >>>> # when 'sriov_max_vfs' is present, the SR-IOV feature will be automatically enabled >>>> # means the max number of VF on guest >>>> >>>> Example commands to create VFs in virtio-net device from the guest: >>>> >>>> guest% readlink -f /sys/class/net/eth1/device >>>> /sys/devices/pci0000:00/0000:00:02.0/0000:01:00.0/virtio1 >>>> guest% echo "2" > /sys/devices/pci0000:00/0000:00:02.0/0000:01:00.0/sriov_numvfs >>>> guest% ip link show >>>> eth0: .... >>>> eth1: .... >>>> eth2: .... #virtual VF created >>>> eth3: .... #virtual VF created >>>> >>>> Please note that communication between VF and PF/VF is not possible by this patch series itself. >>>> >>>> Yui Washizu (1): >>>> virtio-pci: add SR-IOV capability >>>> >>>> hw/pci/msix.c | 8 +++-- >>>> hw/pci/pci.c | 4 +++ >>>> hw/virtio/virtio-pci.c | 62 ++++++++++++++++++++++++++++++---- >>>> include/hw/virtio/virtio-pci.h | 1 + >>>> 4 files changed, 66 insertions(+), 9 deletions(-) >>>> >>>> -- >>>> 2.39.3 >>>>