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path: root/Documentation/vfio-mediated-device.txt
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2018-06-08vfio/mdev: Check globally for duplicate devicesAlex Williamson
When we create an mdev device, we check for duplicates against the parent device and return -EEXIST if found, but the mdev device namespace is global since we'll link all devices from the bus. We do catch this later in sysfs_do_create_link_sd() to return -EEXIST, but with it comes a kernel warning and stack trace for trying to create duplicate sysfs links, which makes it an undesirable response. Therefore we should really be looking for duplicates across all mdev parent devices, or as implemented here, against our mdev device list. Using mdev_list to prevent duplicates means that we can remove mdev_parent.lock, but in order not to serialize mdev device creation and removal globally, we add mdev_device.active which allows UUIDs to be reserved such that we can drop the mdev_list_lock before the mdev device is fully in place. Two behavioral notes; first, mdev_parent.lock had the side-effect of serializing mdev create and remove ops per parent device. This was an implementation detail, not an intentional guarantee provided to the mdev vendor drivers. Vendor drivers can trivially provide this serialization internally if necessary. Second, review comments note the new -EAGAIN behavior when the device, and in particular the remove attribute, becomes visible in sysfs. If a remove is triggered prior to completion of mdev_device_create() the user will see a -EAGAIN error. While the errno is different, receiving an error during this period is not, the previous implementation returned -ENODEV for the same condition. Furthermore, the consistency to the user is improved in the case where mdev_device_remove_ops() returns error. Previously concurrent calls to mdev_device_remove() could see the device disappear with -ENODEV and return in the case of error. Now a user would see -EAGAIN while the device is in this transitory state. Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com> Reviewed-by: Cornelia Huck <cohuck@redhat.com> Acked-by: Halil Pasic <pasic@linux.ibm.com> Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2017-07-14vfio-mediated-device.txt: standardize document formatMauro Carvalho Chehab
Each text file under Documentation follows a different format. Some doesn't even have titles! In this specific document, the title, copyright and authorship are added as if it were a C file! Change its representation to follow the adopted standard, using ReST markups for it to be parseable by Sphinx: - convert document preambule to the proper format; - mark literal blocks; - adjust identation; - use numbered lists for references. Reviewed by: Kirti Wankhede <kwankhede@nvidia.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-04-27docs: Fix a spelling error in vfio-mediated-device.txtStan Drozd
This commit fixes a repeated "the" in vfio-mediated-device.txt and reflows the paragraph. Signed-off-by: Stan Drozd <drozdziak1@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-03-17Documentation: vfio-mediated-device.txt: Fix typosTamara Diaconita
Correct spelling mistakes in vfio-mediates-device.txt to make documentation clear. Signed-off-by: Tamara Diaconita <diaconita.tamara@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2016-12-30vfio-mdev: Make mdev_parent privateAlex Williamson
Rather than hoping for good behavior by marking some elements internal, enforce it by making the entire structure private and creating an accessor function for the one useful external field. Cc: Zhenyu Wang <zhenyuw@linux.intel.com> Cc: Zhi Wang <zhi.a.wang@intel.com> Cc: Jike Song <jike.song@intel.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Reviewed by: Kirti Wankhede <kwankhede@nvidia.com>
2016-12-30vfio-mdev: de-polute the namespace, rename parent_device & parent_opsAlex Williamson
Add an mdev_ prefix so we're not poluting the namespace so much. Cc: Zhenyu Wang <zhenyuw@linux.intel.com> Cc: Zhi Wang <zhi.a.wang@intel.com> Cc: Jike Song <jike.song@intel.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Reviewed by: Kirti Wankhede <kwankhede@nvidia.com>
2016-11-17docs: Sample driver to demonstrate how to use Mediated device framework.Kirti Wankhede
The Sample driver creates mdev device that simulates serial port over PCI card. Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com> Signed-off-by: Neo Jia <cjia@nvidia.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
2016-11-17docs: Add Documentation for Mediated devicesKirti Wankhede
Add file Documentation/vfio-mediated-device.txt that include details of mediated device framework. Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com> Signed-off-by: Neo Jia <cjia@nvidia.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>