From patchwork Thu Aug 25 03:53:55 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kirti Wankhede X-Patchwork-Id: 9298723 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 088AE60459 for ; Thu, 25 Aug 2016 06:16:32 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E241C28D71 for ; Thu, 25 Aug 2016 06:16:31 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D53BD291CB; Thu, 25 Aug 2016 06:16:31 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2AAF328D71 for ; Thu, 25 Aug 2016 06:16:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755279AbcHYGQ2 (ORCPT ); Thu, 25 Aug 2016 02:16:28 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:12855 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751693AbcHYGQ1 (ORCPT ); Thu, 25 Aug 2016 02:16:27 -0400 Received: from hqnvupgp07.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com id ; Wed, 24 Aug 2016 20:53:43 -0700 Received: from HQMAIL101.nvidia.com ([172.20.12.94]) by hqnvupgp07.nvidia.com (PGP Universal service); Wed, 24 Aug 2016 20:49:29 -0700 X-PGP-Universal: processed; by hqnvupgp07.nvidia.com on Wed, 24 Aug 2016 20:49:29 -0700 Received: from HQMAIL106.nvidia.com (172.18.146.12) by HQMAIL101.nvidia.com (172.20.187.10) with Microsoft SMTP Server (TLS) id 15.0.1210.3; Thu, 25 Aug 2016 03:53:36 +0000 Received: from kwankhede-dev.nvidia.com (172.20.13.39) by HQMAIL106.nvidia.com (172.18.146.12) with Microsoft SMTP Server (TLS) id 15.0.1210.3 via Frontend Transport; Thu, 25 Aug 2016 03:53:32 +0000 From: Kirti Wankhede To: , , , CC: , , , , , Kirti Wankhede Subject: [PATCH v7 4/4] docs: Add Documentation for Mediated devices Date: Thu, 25 Aug 2016 09:23:55 +0530 Message-ID: <1472097235-6332-5-git-send-email-kwankhede@nvidia.com> X-Mailer: git-send-email 2.7.0 In-Reply-To: <1472097235-6332-1-git-send-email-kwankhede@nvidia.com> References: <1472097235-6332-1-git-send-email-kwankhede@nvidia.com> X-NVConfidentiality: public MIME-Version: 1.0 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Add file Documentation/vfio-mediated-device.txt that include details of mediated device framework. Signed-off-by: Kirti Wankhede Signed-off-by: Neo Jia Change-Id: I137dd646442936090d92008b115908b7b2c7bc5d Reviewed-on: http://git-master/r/1182512 Reviewed-by: Automatic_Commit_Validation_User --- Documentation/vfio-mediated-device.txt | 203 +++++++++++++++++++++++++++++++++ 1 file changed, 203 insertions(+) create mode 100644 Documentation/vfio-mediated-device.txt diff --git a/Documentation/vfio-mediated-device.txt b/Documentation/vfio-mediated-device.txt new file mode 100644 index 000000000000..237d8eb630b7 --- /dev/null +++ b/Documentation/vfio-mediated-device.txt @@ -0,0 +1,203 @@ +VFIO Mediated devices [1] +------------------------------------------------------------------------------- + +There are more and more use cases/demands to virtualize the DMA devices which +doesn't have SR_IOV capability built-in. To do this, drivers of different +devices had to develop their own management interface and set of APIs and then +integrate it to user space software. We've identified common requirements and +unified management interface for such devices to make user space software +integration easier. + +The VFIO driver framework provides unified APIs for direct device access. It is +an IOMMU/device agnostic framework for exposing direct device access to +user space, in a secure, IOMMU protected environment. This framework is +used for multiple devices like GPUs, network adapters and compute accelerators. +With direct device access, virtual machines or user space applications have +direct access of physical device. This framework is reused for mediated devices. + +Mediated core driver provides a common interface for mediated device management +that can be used by drivers of different devices. This module provides a generic +interface to create/destroy mediated device, add/remove it to mediated bus +driver, add/remove device to IOMMU group. It also provides an interface to +register bus driver, for example, Mediated VFIO mdev driver is designed for +mediated devices and supports VFIO APIs. Mediated bus driver add/delete mediated +device to VFIO Group. + +Below is the high Level block diagram, with NVIDIA, Intel and IBM devices +as example, since these are the devices which are going to actively use +this module as of now. + + +---------------+ + | | + | +-----------+ | mdev_register_driver() +--------------+ + | | | +<------------------------+ | + | | mdev | | | | + | | bus | +------------------------>+ vfio_mdev.ko |<-> VFIO user + | | driver | | probe()/remove() | | APIs + | | | | +--------------+ + | +-----------+ | + | | + | MDEV CORE | + | MODULE | + | mdev.ko | + | +-----------+ | mdev_register_device() +--------------+ + | | | +<------------------------+ | + | | | | | nvidia.ko |<-> physical + | | | +------------------------>+ | device + | | | | callbacks +--------------+ + | | Physical | | + | | device | | mdev_register_device() +--------------+ + | | interface | |<------------------------+ | + | | | | | i915.ko |<-> physical + | | | +------------------------>+ | device + | | | | callbacks +--------------+ + | | | | + | | | | mdev_register_device() +--------------+ + | | | +<------------------------+ | + | | | | | ccw_device.ko|<-> physical + | | | +------------------------>+ | device + | | | | callbacks +--------------+ + | +-----------+ | + +---------------+ + + +Registration Interfaces +------------------------------------------------------------------------------- + +Mediated core driver provides two types of registration interfaces: + +1. Registration interface for mediated bus driver: +------------------------------------------------- + /* + * struct mdev_driver [2] - Mediated device's driver + * @name: driver name + * @probe: called when new device created + * @remove: called when device removed + * @driver: device driver structure + */ + struct mdev_driver { + const char *name; + int (*probe) (struct device *dev); + void (*remove) (struct device *dev); + struct device_driver driver; + }; + +Mediated bus driver for mdev should use this interface to register and +unregister with core driver respectively: + +extern int mdev_register_driver(struct mdev_driver *drv, struct module *owner); +extern void mdev_unregister_driver(struct mdev_driver *drv); + +Mediated bus driver is responsible to add/delete mediated devices to/from VFIO +group when devices are bound and unbound to the driver. + +2. Physical device driver interface: +----------------------------------- +This interface [3] provides a set of APIs to manage physical device related work +in its driver. APIs are: + +* dev_attr_groups: attributes of the parent device. +* mdev_attr_groups: attributes of the mediated device. +* supported_config: to provide supported configuration list by the driver. +* create: to allocate basic resources in driver for a mediated device. +* destroy: to free resources in driver when mediated device is destroyed. +* reset: to free and reallocate resources in driver on mediated device reset. +* set_online_status: to change online status of mediated device. +* get_online_status: to get current (online/offline) status of mediated device. +* read : read emulation callback. +* write: write emulation callback. +* mmap: mmap emulation callback. +* get_irq_info: to retrieve information about mediated device's IRQ. +* set_irqs: gives interrupt configuration information that VMM sets. +* get_region_info: to provide region size and its flags for the mediated device. + Vendor driver can provide the capability id and corresponding capability + structure if want to support a capability. +* get_device_info: to retrieve VFIO device related flags, number of regions and + number of IRQs supported. + +Drivers should use this interface to register and unregister device to mdev core +driver respectively: + +extern int mdev_register_device(struct device *dev, + const struct parent_ops *ops); +extern void mdev_unregister_device(struct device *dev); + +Mediated device management interface via sysfs +------------------------------------------------------------------------------- +This is the interface that allows user space software, like libvirt, to query +and configure mediated device in a HW agnostic fashion. This management +interface provide flexibility to underlying physical device's driver to support +mediated device hotplug, multiple mediated devices per virtual machine, multiple +mediated devices from different physical devices, etc. + +Under per-physical device sysfs: +-------------------------------- + +* mdev_supported_types: (read only) + List the current supported mediated device types and its details. + +* mdev_create: (write only) + Create a mediated device on target physical device. + Input syntax: + where, + UUID: mediated device's UUID + params: extra parameters required by driver + Example: + # echo "12345678-1234-1234-1234-123456789abc:0" > + /sys/bus/pci/devices/0000\:05\:00.0/mdev_create + +* mdev_destroy: (write only) + Destroy a mediated device on a target physical device. + Input syntax: + where, + UUID: mediated device's UUID + Example: + # echo "12345678-1234-1234-1234-123456789abc" > + /sys/bus/pci/devices/0000\:05\:00.0/mdev_destroy + +Under per mdev device: +---------------------------------------- + +* online: (read write) + Read on this file provides current status of mediated device (0 or 1). + Write on this file (0 or 1) will change the state of mediated device. + This trigger the registration callback to notify the driver to commit + or free mediated device resources. This callback is blocking call, + successful return of this call will indicate requested mdev resources + has been fully committed, the VMM should continue. + Example: + # echo "1|0" > /sys/bus/mdev/devices/$mdev_UUID/online + + +Mediated device Hotplug: +----------------------- + +To support mediated device hotplug, and can be +accessed during VM runtime, and the corresponding registration callback is +invoked to allow driver to support hotplug. + +Translation APIs for Mediated device +------------------------------------------------------------------------------ + +Below APIs are provided for user pfn to host pfn translation in VFIO driver: + +extern long vfio_pin_pages(struct device *dev, unsigned long *user_pfn, + long npage, int prot, unsigned long *phys_pfn); + +extern long vfio_unpin_pages(struct device *dev, unsigned long *pfn, + long npage); + +These functions call back into the backend IOMMU module using two callbacks of +struct vfio_iommu_driver_ops, pin_pages and unpin_pages [4]. Currently these are +supported in TYPE1 IOMMU module. To enable the same for other IOMMU backend +modules, such as PPC64 sPAPR module, they need to provide these two callback +functions. + +References +------------------------------------------------------------------------------- + +[1] See Documentation/vfio.txt for more information on VFIO. +[2] struct mdev_driver in include/linux/mdev.h +[3] struct parent_ops in include/linux/mdev.h +[4] struct vfio_iommu_driver_ops in include/linux/vfio.h +