kernel/linux.git/drivers/vfio/mdev, branch v4.19.112

vfio/mdev: Fix aborting mdev child device removal if one fails

2020-01-27T13:50:46+00:00

[ Upstream commit 6093e348a5e2475c5bb2e571346460f939998670 ] device_for_each_child() stops executing callback function for remaining child devices, if callback hits an error. Each child mdev device is independent of each other. While unregistering parent device, mdev core must remove all child mdev devices. Therefore, mdev_device_remove_cb() always returns success so that device_for_each_child doesn't abort if one child removal hits error. While at it, improve remove and unregister functions for below simplicity. There isn't need to pass forced flag pointer during mdev parent removal which invokes mdev_device_remove(). So simplify the flow. mdev_device_remove() is called from two paths. 1. mdev_unregister_driver() mdev_device_remove_cb() mdev_device_remove() 2. remove_store() mdev_device_remove() Fixes: 7b96953bc640 ("vfio: Mediated device Core driver") Reviewed-by: Maxim Levitsky Signed-off-by: Parav Pandit Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin

vfio/mdev: Follow correct remove sequence

2020-01-27T13:50:45+00:00

[ Upstream commit a6d6f4f160f76d840e59affe664b8d3159e23056 ] mdev_remove_sysfs_files() should follow exact mirror sequence of a create, similar to what is followed in error unwinding path of mdev_create_sysfs_files(). Fixes: 6a62c1dfb5c7 ("vfio/mdev: Re-order sysfs attribute creation") Reviewed-by: Cornelia Huck Reviewed-by: Maxim Levitsky Signed-off-by: Parav Pandit Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin

vfio/mdev: Avoid release parent reference during error path

2020-01-27T13:50:45+00:00

[ Upstream commit 60e7f2c3fe9919cee9534b422865eed49f4efb15 ] During mdev parent registration in mdev_register_device(), if parent device is duplicate, it releases the reference of existing parent device. This is incorrect. Existing parent device should not be touched. Fixes: 7b96953bc640 ("vfio: Mediated device Core driver") Reviewed-by: Cornelia Huck Reviewed-by: Kirti Wankhede Reviewed-by: Maxim Levitsky Signed-off-by: Parav Pandit Signed-off-by: Alex Williamson Signed-off-by: Sasha Levin

vfio/mdev: Re-order sysfs attribute creation

2018-06-08T16:24:30+00:00

There exists a gap at the end of mdev_device_create() where the device is visible to userspace, but we're not yet ready to handle removal, as triggered through the 'remove' attribute. We handle this properly in mdev_device_remove() with an -EAGAIN return, but we can marginally reduce this gap by adding this attribute as a final step of our sysfs setup. Reviewed-by: Kirti Wankhede Reviewed-by: Cornelia Huck Acked-by: Halil Pasic Signed-off-by: Alex Williamson

vfio/mdev: Check globally for duplicate devices

2018-06-08T16:24:27+00:00

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 Reviewed-by: Cornelia Huck Acked-by: Halil Pasic Acked-by: Zhenyu Wang Signed-off-by: Alex Williamson

vfio: mdev: make a couple of functions and structure vfio_mdev_driver static

2018-01-09T19:13:08+00:00

The functions vfio_mdev_probe, vfio_mdev_remove and the structure vfio_mdev_driver are only used in this file, so make them static. Clean up sparse warnings: drivers/vfio/mdev/vfio_mdev.c:114:5: warning: no previous prototype for 'vfio_mdev_probe' [-Wmissing-prototypes] drivers/vfio/mdev/vfio_mdev.c:121:6: warning: no previous prototype for 'vfio_mdev_remove' [-Wmissing-prototypes] Signed-off-by: Xiongwei Song Reviewed-by: Quan Xu Reviewed-by: Liu, Yi L Reviewed-by: Kirti Wankhede Signed-off-by: Alex Williamson

vfio/mdev: Use a module softdep for vfio_mdev

2017-02-08T20:13:25+00:00

Use an explicit module softdep rather than a request module call such that the dependency is exposed to userspace. This allows us to more easily support modules loaded at initrd time. Reviewed by: Kirti Wankhede Signed-off-by: Alex Williamson

vfio-mdev: Make mdev_device private and abstract interfaces

2016-12-30T15:13:44+00:00

Abstract access to mdev_device so that we can define which interfaces are public rather than relying on comments in the structure. Cc: Zhenyu Wang Cc: Zhi Wang Signed-off-by: Alex Williamson Reviewed-by: Jike Song Reviewed by: Kirti Wankhede

vfio-mdev: Make mdev_parent private

2016-12-30T15:13:41+00:00

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 Cc: Zhi Wang Cc: Jike Song Signed-off-by: Alex Williamson Reviewed by: Kirti Wankhede

vfio-mdev: de-polute the namespace, rename parent_device & parent_ops

2016-12-30T15:13:38+00:00

Add an mdev_ prefix so we're not poluting the namespace so much. Cc: Zhenyu Wang Cc: Zhi Wang Cc: Jike Song Signed-off-by: Alex Williamson Reviewed by: Kirti Wankhede