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[109.67.15.113]) by smtp.gmail.com with ESMTPSA id l1sm1795870wmi.15.2020.12.16.01.16.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Dec 2020 01:16:20 -0800 (PST) Date: Wed, 16 Dec 2020 04:16:17 -0500 From: "Michael S. Tsirkin" To: Parav Pandit Cc: virtualization@lists.linux-foundation.org, jasowang@redhat.com, elic@nvidia.com, netdev@vger.kernel.org Subject: Re: [PATCH 0/7] Introduce vdpa management tool Message-ID: <20201216041506-mutt-send-email-mst@kernel.org> References: <20201112064005.349268-1-parav@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201112064005.349268-1-parav@nvidia.com> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Nov 12, 2020 at 08:39:58AM +0200, Parav Pandit wrote: > This patchset covers user requirements for managing existing vdpa devices, > using a tool and its internal design notes for kernel drivers. I applied bugfix patches 1 and 2. Others conflict with vdpa sim block support, pls rebase. > Background and user requirements: > ---------------------------------- > (1) Currently VDPA device is created by driver when driver is loaded. > However, user should have a choice when to create or not create a vdpa device > for the underlying parent device. > > For example, mlx5 PCI VF and subfunction device supports multiple classes of > device such netdev, vdpa, rdma. Howevever it is not required to always created > vdpa device for such device. > > (2) In another use case, a device may support creating one or multiple vdpa > device of same or different class such as net and block. > Creating vdpa devices at driver load time further limits this use case. > > (3) A user should be able to monitor and query vdpa queue level or device level > statistics for a given vdpa device. > > (4) A user should be able to query what class of vdpa devices are supported > by its parent device. > > (5) A user should be able to view supported features and negotiated features > of the vdpa device. > > (6) A user should be able to create a vdpa device in vendor agnostic manner > using single tool. > > Hence, it is required to have a tool through which user can create one or more > vdpa devices from a parent device which addresses above user requirements. > > Example devices: > ---------------- > +-----------+ +-----------+ +---------+ +--------+ +-----------+ > |vdpa dev 0 | |vdpa dev 1 | |rdma dev | |netdev | |vdpa dev 3 | > |type=net | |type=block | |mlx5_0 | |ens3f0 | |type=net | > +----+------+ +-----+-----+ +----+----+ +-----+--+ +----+------+ > | | | | | > | | | | | > +----+-----+ | +----+----+ | +----+----+ > | mlx5 +--------+ |mlx5 +-------+ |mlx5 | > |pci vf 2 | |pci vf 4 | |pci sf 8 | > |03:00:2 | |03:00.4 | |mlx5_sf.8| > +----+-----+ +----+----+ +----+----+ > | | | > | +----+-----+ | > +----------------------+mlx5 +----------------+ > |pci pf 0 | > |03:00.0 | > +----------+ > > vdpa tool: > ---------- > vdpa tool is a tool to create, delete vdpa devices from a parent device. It is a > tool that enables user to query statistics, features and may be more attributes > in future. > > vdpa tool command draft: > ------------------------ > (a) List parent devices which supports creating vdpa devices. > It also shows which class types supported by this parent device. > In below command example two parent devices support vdpa device creation. > First is PCI VF whose bdf is 03.00:2. > Second is PCI VF whose name is 03:00.4. > Third is PCI SF whose name is mlx5_core.sf.8 > > $ vdpa parentdev list > vdpasim > supported_classes > net > pci/0000:03.00:3 > supported_classes > net block > pci/0000:03.00:4 > supported_classes > net block > auxiliary/mlx5_core.sf.8 > supported_classes > net > > (b) Now add a vdpa device of networking class and show the device. > $ vdpa dev add parentdev pci/0000:03.00:2 type net name foo0 $ vdpa dev show foo0 > foo0: parentdev pci/0000:03.00:2 type network parentdev vdpasim vendor_id 0 max_vqs 2 max_vq_size 256 > > (c) Show features of a vdpa device > $ vdpa dev features show foo0 > supported > iommu platform > version 1 > > (d) Dump vdpa device statistics > $ vdpa dev stats show foo0 > kickdoorbells 10 > wqes 100 > > (e) Now delete a vdpa device previously created. > $ vdpa dev del foo0 > > vdpa tool support in this patchset: > ----------------------------------- > vdpa tool is created to create, delete and query vdpa devices. > examples: > Show vdpa parent device that supports creating, deleting vdpa devices. > > $ vdpa parentdev show > vdpasim: > supported_classes > net > > $ vdpa parentdev show -jp > { > "show": { > "vdpasim": { > "supported_classes": { > "net" > } > } > } > > Create a vdpa device of type networking named as "foo2" from the parent device vdpasim: > > $ vdpa dev add parentdev vdpasim type net name foo2 > > Show the newly created vdpa device by its name: > $ vdpa dev show foo2 > foo2: type network parentdev vdpasim vendor_id 0 max_vqs 2 max_vq_size 256 > > $ vdpa dev show foo2 -jp > { > "dev": { > "foo2": { > "type": "network", > "parentdev": "vdpasim", > "vendor_id": 0, > "max_vqs": 2, > "max_vq_size": 256 > } > } > } > > Delete the vdpa device after its use: > $ vdpa dev del foo2 > > vdpa tool support by kernel: > ---------------------------- > vdpa tool user interface will be supported by existing vdpa kernel framework, > i.e. drivers/vdpa/vdpa.c It services user command through a netlink interface. > > Each parent device registers supported callback operations with vdpa subsystem > through which vdpa device(s) can be managed. > > FAQs: > ----- > 1. Where does userspace vdpa tool reside which users can use? > Ans: vdpa tool can possibly reside in iproute2 [1] as it enables user to > create vdpa net devices. > > 2. Why not create and delete vdpa device using sysfs/configfs? > Ans: > (a) A device creation may involve passing one or more attributes. > Passing multiple attributes and returning error code and more verbose > information for invalid attributes cannot be handled by sysfs/configfs. > > (b) netlink framework is rich that enables user space and kernel driver to > provide nested attributes. > > (c) Exposing device specific file under sysfs without net namespace > awareness exposes details to multiple containers. Instead exposing > attributes via a netlink socket secures the communication channel with kernel. > > (d) netlink socket interface enables to run syscaller kernel tests. > > 3. Why not use ioctl() interface? > Ans: ioctl() interface replicates the necessary plumbing which already > exists through netlink socket. > > 4. What happens when one or more user created vdpa devices exist for a > parent PCI VF or SF and such parent device is removed? > Ans: All user created vdpa devices are removed that belong to a parent. > > [1] git://git.kernel.org/pub/scm/network/iproute2/iproute2-next.git > > Next steps: > ----------- > (a) Post this patchset and iproute2/vdpa inclusion, remaining two drivers > will be coverted to support vdpa tool instead of creating unmanaged default > device on driver load. > (b) More net specific parameters such as mac, mtu will be added. > (c) Features bits get and set interface will be added. > > Parav Pandit (7): > vdpa: Add missing comment for virtqueue count > vdpa: Use simpler version of ida allocation > vdpa: Extend routine to accept vdpa device name > vdpa: Define vdpa parent device, ops and a netlink interface > vdpa: Enable a user to add and delete a vdpa device > vdpa: Enable user to query vdpa device info > vdpa/vdpa_sim: Enable user to create vdpasim net devices > > drivers/vdpa/Kconfig | 1 + > drivers/vdpa/ifcvf/ifcvf_main.c | 2 +- > drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +- > drivers/vdpa/vdpa.c | 511 +++++++++++++++++++++++++++++- > drivers/vdpa/vdpa_sim/vdpa_sim.c | 81 ++++- > include/linux/vdpa.h | 46 ++- > include/uapi/linux/vdpa.h | 41 +++ > 7 files changed, 660 insertions(+), 24 deletions(-) > create mode 100644 include/uapi/linux/vdpa.h > > -- > 2.26.2