The RUNNING_P2P state is designed to support multiple devices in the same
VM that are doing P2P transactions between themselves. When in RUNNING_P2P
the device must be able to accept incoming P2P transactions but should not
generate outgoing P2P transactions.
As an optional extension to the mandatory states it is defined as
in between STOP and RUNNING:
STOP -> RUNNING_P2P -> RUNNING -> RUNNING_P2P -> STOP
For drivers that are unable to support RUNNING_P2P the core code
silently merges RUNNING_P2P and RUNNING together. Unless driver support
is present, the new state cannot be used in SET_STATE.
Drivers that support this will be required to implement 4 FSM arcs
beyond the basic FSM. 2 of the basic FSM arcs become combination
transitions.
Compared to the v1 clarification, NDMA is redefined into FSM states and is
described in terms of the desired P2P quiescent behavior, noting that
halting all DMA is an acceptable implementation.
Link: https://lore.kernel.org/all/20220224142024.147653-11-yishaih@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Replace the existing region based migration protocol with an ioctl based
protocol. The two protocols have the same general semantic behaviors, but
the way the data is transported is changed.
This is the STOP_COPY portion of the new protocol, it defines the 5 states
for basic stop and copy migration and the protocol to move the migration
data in/out of the kernel.
Compared to the clarification of the v1 protocol Alex proposed:
https://lore.kernel.org/r/163909282574.728533.7460416142511440919.stgit@omen
This has a few deliberate functional differences:
- ERROR arcs allow the device function to remain unchanged.
- The protocol is not required to return to the original state on
transition failure. Instead userspace can execute an unwind back to
the original state, reset, or do something else without needing kernel
support. This simplifies the kernel design and should userspace choose
a policy like always reset, avoids doing useless work in the kernel
on error handling paths.
- PRE_COPY is made optional, userspace must discover it before using it.
This reflects the fact that the majority of drivers we are aware of
right now will not implement PRE_COPY.
- segmentation is not part of the data stream protocol, the receiver
does not have to reproduce the framing boundaries.
The hybrid FSM for the device_state is described as a Mealy machine by
documenting each of the arcs the driver is required to implement. Defining
the remaining set of old/new device_state transitions as 'combination
transitions' which are naturally defined as taking multiple FSM arcs along
the shortest path within the FSM's digraph allows a complete matrix of
transitions.
A new VFIO_DEVICE_FEATURE of VFIO_DEVICE_FEATURE_MIG_DEVICE_STATE is
defined to replace writing to the device_state field in the region. This
allows returning a brand new FD whenever the requested transition opens
a data transfer session.
The VFIO core code implements the new feature and provides a helper
function to the driver. Using the helper the driver only has to
implement 6 of the FSM arcs and the other combination transitions are
elaborated consistently from those arcs.
A new VFIO_DEVICE_FEATURE of VFIO_DEVICE_FEATURE_MIGRATION is defined to
report the capability for migration and indicate which set of states and
arcs are supported by the device. The FSM provides a lot of flexibility to
make backwards compatible extensions but the VFIO_DEVICE_FEATURE also
allows for future breaking extensions for scenarios that cannot support
even the basic STOP_COPY requirements.
The VFIO_DEVICE_FEATURE_MIG_DEVICE_STATE with the GET option (i.e.
VFIO_DEVICE_FEATURE_GET) can be used to read the current migration state
of the VFIO device.
Data transfer sessions are now carried over a file descriptor, instead of
the region. The FD functions for the lifetime of the data transfer
session. read() and write() transfer the data with normal Linux stream FD
semantics. This design allows future expansion to support poll(),
io_uring, and other performance optimizations.
The complicated mmap mode for data transfer is discarded as current qemu
doesn't take meaningful advantage of it, and the new qemu implementation
avoids substantially all the performance penalty of using a read() on the
region.
Link: https://lore.kernel.org/all/20220224142024.147653-10-yishaih@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Invoke a new device op 'device_feature' to handle just the data array
portion of the command. This lifts the ioctl validation to the core code
and makes it simpler for either the core code, or layered drivers, to
implement their own feature values.
Provide vfio_check_feature() to consolidate checking the flags/etc against
what the driver supports.
Link: https://lore.kernel.org/all/20220224142024.147653-9-yishaih@nvidia.com
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
vfio.c abuses (misuses) "/**", which indicates the beginning of
kernel-doc notation in the kernel tree. This causes a bunch of
kernel-doc complaints about this source file, so quieten all of
them by changing all "/**" to "/*".
vfio.c:236: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* IOMMU driver registration
vfio.c:236: warning: missing initial short description on line:
* IOMMU driver registration
vfio.c:295: warning: expecting prototype for Container objects(). Prototype was for vfio_container_get() instead
vfio.c:317: warning: expecting prototype for Group objects(). Prototype was for __vfio_group_get_from_iommu() instead
vfio.c:496: warning: Function parameter or member 'device' not described in 'vfio_device_put'
vfio.c:496: warning: expecting prototype for Device objects(). Prototype was for vfio_device_put() instead
vfio.c:599: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* Async device support
vfio.c:599: warning: missing initial short description on line:
* Async device support
vfio.c:693: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* VFIO driver API
vfio.c:693: warning: missing initial short description on line:
* VFIO driver API
vfio.c:835: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* Get a reference to the vfio_device for a device. Even if the
vfio.c:835: warning: missing initial short description on line:
* Get a reference to the vfio_device for a device. Even if the
vfio.c:969: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* VFIO base fd, /dev/vfio/vfio
vfio.c:969: warning: missing initial short description on line:
* VFIO base fd, /dev/vfio/vfio
vfio.c:1187: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* VFIO Group fd, /dev/vfio/$GROUP
vfio.c:1187: warning: missing initial short description on line:
* VFIO Group fd, /dev/vfio/$GROUP
vfio.c:1540: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* VFIO Device fd
vfio.c:1540: warning: missing initial short description on line:
* VFIO Device fd
vfio.c:1615: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* External user API, exported by symbols to be linked dynamically.
vfio.c:1615: warning: missing initial short description on line:
* External user API, exported by symbols to be linked dynamically.
vfio.c:1663: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* External user API, exported by symbols to be linked dynamically.
vfio.c:1663: warning: missing initial short description on line:
* External user API, exported by symbols to be linked dynamically.
vfio.c:1742: warning: Function parameter or member 'caps' not described in 'vfio_info_cap_add'
vfio.c:1742: warning: Function parameter or member 'size' not described in 'vfio_info_cap_add'
vfio.c:1742: warning: Function parameter or member 'id' not described in 'vfio_info_cap_add'
vfio.c:1742: warning: Function parameter or member 'version' not described in 'vfio_info_cap_add'
vfio.c:1742: warning: expecting prototype for Sub(). Prototype was for vfio_info_cap_add() instead
vfio.c:2276: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* Module/class support
vfio.c:2276: warning: missing initial short description on line:
* Module/class support
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Cornelia Huck <cohuck@redhat.com>
Cc: kvm@vger.kernel.org
Link: https://lore.kernel.org/r/38a9cb92-a473-40bf-b8f9-85cc5cfc2da4@infradead.org
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Modernize how vfio is creating the group char dev and sysfs presence.
These days drivers with state should use cdev_device_add() and
cdev_device_del() to manage the cdev and sysfs lifetime.
This API requires the driver to put the struct device and struct cdev
inside its state struct (vfio_group), and then use the usual
device_initialize()/cdev_device_add()/cdev_device_del() sequence.
Split the code to make this possible:
- vfio_group_alloc()/vfio_group_release() are pair'd functions to
alloc/free the vfio_group. release is done under the struct device
kref.
- vfio_create_group()/vfio_group_put() are pairs that manage the
sysfs/cdev lifetime. Once the uses count is zero the vfio group's
userspace presence is destroyed.
- The IDR is replaced with an IDA. container_of(inode->i_cdev)
is used to get back to the vfio_group during fops open. The IDA
assigns unique minor numbers.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/5-v3-2fdfe4ca2cc6+18c-vfio_group_cdev_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The next patch adds a struct device to the struct vfio_group, and it is
confusing/bad practice to have two krefs in the same struct. This kref is
controlling the period when the vfio_group is registered in sysfs, and
visible in the internal lookup. Switch it to a refcount_t instead.
The refcount_dec_and_mutex_lock() is still required because we need
atomicity of the list searches and sysfs presence.
Reviewed-by: Liu Yi L <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v3-2fdfe4ca2cc6+18c-vfio_group_cdev_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
If vfio_create_group() searches the group list and returns an already
existing group it does not put back the iommu_group reference that the
caller passed in.
Change the semantic of vfio_create_group() to not move the reference in
from the caller, but instead obtain a new reference inside and leave the
caller's reference alone. The two callers must now call iommu_group_put().
This is an unlikely race as the only caller that could hit it has already
searched the group list before attempting to create the group.
Fixes: cba3345cc4 ("vfio: VFIO core")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/3-v3-2fdfe4ca2cc6+18c-vfio_group_cdev_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Split vfio_group_get_from_iommu() into __vfio_group_get_from_iommu() so
that vfio_create_group() can call it to consolidate this duplicated code.
Reviewed-by: Liu Yi L <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/2-v3-2fdfe4ca2cc6+18c-vfio_group_cdev_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
iommu_group_register_notifier()/iommu_group_unregister_notifier() are
built using a blocking_notifier_chain which integrates a rwsem. The
notifier function cannot be running outside its registration.
When considering how the notifier function interacts with create/destroy
of the group there are two fringe cases, the notifier starts before
list_add(&vfio.group_list) and the notifier runs after the kref
becomes 0.
Prior to vfio_create_group() unlocking and returning we have
container_users == 0
device_list == empty
And this cannot change until the mutex is unlocked.
After the kref goes to zero we must also have
container_users == 0
device_list == empty
Both are required because they are balanced operations and a 0 kref means
some caller became unbalanced. Add the missing assertion that
container_users must be zero as well.
These two facts are important because when checking each operation we see:
- IOMMU_GROUP_NOTIFY_ADD_DEVICE
Empty device_list avoids the WARN_ON in vfio_group_nb_add_dev()
0 container_users ends the call
- IOMMU_GROUP_NOTIFY_BOUND_DRIVER
0 container_users ends the call
Finally, we have IOMMU_GROUP_NOTIFY_UNBOUND_DRIVER, which only deletes
items from the unbound list. During creation this list is empty, during
kref == 0 nothing can read this list, and it will be freed soon.
Since the vfio_group_release() doesn't hold the appropriate lock to
manipulate the unbound_list and could race with the notifier, move the
cleanup to directly before the kfree.
This allows deleting all of the deferred group put code.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Liu Yi L <yi.l.liu@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/1-v3-2fdfe4ca2cc6+18c-vfio_group_cdev_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Pass the group flags to ->attach_group and remove the messy check for
the bus type.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-12-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Create a new private drivers/vfio/vfio.h header for the interface between
the VFIO core and the iommu drivers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-10-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The read, write and mmap methods are never implemented, so remove them.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-9-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reuse the logic in vfio_noiommu_group_alloc to allocate a fake
single-device iommu group for mediated devices by factoring out a common
function, and replacing the noiommu boolean field in struct vfio_group
with an enum to distinguish the three different kinds of groups.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-8-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Just pass a noiommu argument to vfio_create_group and set up the
->noiommu flag directly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-7-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Split the actual noiommu group creation from vfio_iommu_group_get into a
new helper, and open code the rest of vfio_iommu_group_get in its only
caller. This creates an entirely separate and clear code path for the
noiommu group creation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-6-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Factor out a helper to find or allocate the vfio_group to reduce the
spagetthi code in vfio_register_group_dev a little.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-5-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
vfio_noiommu_attach_group has two callers:
1) __vfio_container_attach_groups is called by vfio_ioctl_set_iommu,
which just called vfio_iommu_driver_allowed
2) vfio_group_set_container requires already checks ->noiommu on the
vfio_group, which is propagated from the iommudata in
vfio_create_group
so this check is entirely superflous and can be removed.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-4-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Factor out a little helper to make the checks for the noiommu driver less
ugly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-3-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
We don't need to hold a reference to the group in the driver as well as
obtain a reference to the same group as the first thing
vfio_register_group_dev() does.
Since the drivers never use the group move this all into the core code.
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-2-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Currently the driver ops have an open/release pair that is called once
each time a device FD is opened or closed. Add an additional set of
open/close_device() ops which are called when the device FD is opened for
the first time and closed for the last time.
An analysis shows that all of the drivers require this semantic. Some are
open coding it as part of their reflck implementation, and some are just
buggy and miss it completely.
To retain the current semantics PCI and FSL depend on, introduce the idea
of a "device set" which is a grouping of vfio_device's that share the same
lock around opening.
The device set is established by providing a 'set_id' pointer. All
vfio_device's that provide the same pointer will be joined to the same
singleton memory and lock across the whole set. This effectively replaces
the oddly named reflck.
After conversion the set_id will be sourced from:
- A struct device from a fsl_mc_device (fsl)
- A struct pci_slot (pci)
- A struct pci_bus (pci)
- The struct vfio_device (everything)
The design ensures that the above pointers are live as long as the
vfio_device is registered, so they form reliable unique keys to group
vfio_devices into sets.
This implementation uses xarray instead of searching through the driver
core structures, which simplifies the somewhat tricky locking in this
area.
Following patches convert all the drivers.
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/4-v4-9ea22c5e6afb+1adf-vfio_reflck_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This pairs with vfio_init_group_dev() and allows undoing any state that is
stored in the vfio_device unrelated to registration. Add appropriately
placed calls to all the drivers.
The following patch will use this to add pre-registration state for the
device set.
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/3-v4-9ea22c5e6afb+1adf-vfio_reflck_jgg@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Remove code duplication and move module refcounting to the subsystem
module.
Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20210518192133.59195-2-mgurtovoy@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
There are no longer any users, so it can go away. Everything is using
container_of now.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <14-v3-225de1400dfc+4e074-vfio1_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This is the standard kernel pattern, the ops associated with a struct get
the struct pointer in for typesafety. The expected design is to use
container_of to cleanly go from the subsystem level type to the driver
level type without having any type erasure in a void *.
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <12-v3-225de1400dfc+4e074-vfio1_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
mdev gets little benefit because it doesn't actually do anything, however
it is the last user, so move the vfio_init/register/unregister_group_dev()
code here for now.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Liu Yi L <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <10-v3-225de1400dfc+4e074-vfio1_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This makes the struct vfio_device part of the public interface so it
can be used with container_of and so forth, as is typical for a Linux
subystem.
This is the first step to bring some type-safety to the vfio interface by
allowing the replacement of 'void *' and 'struct device *' inputs with a
simple and clear 'struct vfio_device *'
For now the self-allocating vfio_add_group_dev() interface is kept so each
user can be updated as a separate patch.
The expected usage pattern is
driver core probe() function:
my_device = kzalloc(sizeof(*mydevice));
vfio_init_group_dev(&my_device->vdev, dev, ops, mydevice);
/* other driver specific prep */
vfio_register_group_dev(&my_device->vdev);
dev_set_drvdata(dev, my_device);
driver core remove() function:
my_device = dev_get_drvdata(dev);
vfio_unregister_group_dev(&my_device->vdev);
/* other driver specific tear down */
kfree(my_device);
Allowing the driver to be able to use the drvdata and vfio_device to go
to/from its own data.
The pattern also makes it clear that vfio_register_group_dev() must be
last in the sequence, as once it is called the core code can immediately
start calling ops. The init/register gap is provided to allow for the
driver to do setup before ops can be called and thus avoid races.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Liu Yi L <yi.l.liu@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <3-v3-225de1400dfc+4e074-vfio1_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The vfio_device is using a 'sleep until all refs go to zero' pattern for
its lifetime, but it is indirectly coded by repeatedly scanning the group
list waiting for the device to be removed on its own.
Switch this around to be a direct representation, use a refcount to count
the number of places that are blocking destruction and sleep directly on a
completion until that counter goes to zero. kfree the device after other
accesses have been excluded in vfio_del_group_dev(). This is a fairly
common Linux idiom.
Due to this we can now remove kref_put_mutex(), which is very rarely used
in the kernel. Here it is being used to prevent a zero ref device from
being seen in the group list. Instead allow the zero ref device to
continue to exist in the device_list and use refcount_inc_not_zero() to
exclude it once refs go to zero.
This patch is organized so the next patch will be able to alter the API to
allow drivers to provide the kfree.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <2-v3-225de1400dfc+4e074-vfio1_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The vfio_device->group value has a get obtained during
vfio_add_group_dev() which gets moved from the stack to vfio_device->group
in vfio_group_create_device().
The reference remains until we reach the end of vfio_del_group_dev() when
it is put back.
Thus anything that already has a kref on the vfio_device is guaranteed a
valid group pointer. Remove all the extra reference traffic.
It is tricky to see, but the get at the start of vfio_del_group_dev() is
actually pairing with the put hidden inside vfio_device_put() a few lines
below.
A later patch merges vfio_group_create_device() into vfio_add_group_dev()
which makes the ownership and error flow on the create side easier to
follow.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Message-Id: <1-v3-225de1400dfc+4e074-vfio1_jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Define a vfio_iommu_driver_ops notify callback, for sending events to
the driver. Drivers are not required to provide the callback, and
may ignore any events. The handling of events is driver specific.
Define the CONTAINER_CLOSE event, called when the container's file
descriptor is closed. This event signifies that no further state changes
will occur via container ioctl's.
Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Add the API for getting the domain from a vfio group. This could be used
by the physical device drivers which rely on the vfio/mdev framework for
mediated device user level access. The typical use case like below:
unsigned int pasid;
struct vfio_group *vfio_group;
struct iommu_domain *iommu_domain;
struct device *dev = mdev_dev(mdev);
struct device *iommu_device = mdev_get_iommu_device(dev);
if (!iommu_device ||
!iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX))
return -EINVAL;
vfio_group = vfio_group_get_external_user_from_dev(dev);
if (IS_ERR_OR_NULL(vfio_group))
return -EFAULT;
iommu_domain = vfio_group_iommu_domain(vfio_group);
if (IS_ERR_OR_NULL(iommu_domain)) {
vfio_group_put_external_user(vfio_group);
return -EFAULT;
}
pasid = iommu_aux_get_pasid(iommu_domain, iommu_device);
if (pasid < 0) {
vfio_group_put_external_user(vfio_group);
return -EFAULT;
}
/* Program device context with pasid value. */
...
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
When error occurs, need to put vfio group after a successful get.
Fixes: 95fc87b441 ("vfio: Selective dirty page tracking if IOMMU backed device pins pages")
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Page pinning is used both to translate and pin device mappings for DMA
purpose, as well as to indicate to the IOMMU backend to limit the dirty
page scope to those pages that have been pinned, in the case of an IOMMU
backed device.
To support this, the vfio_pin_pages() interface limits itself to only
singleton groups such that the IOMMU backend can consider dirty page
scope only at the group level. Implement the same requirement for the
vfio_group_pin_pages() interface.
Fixes: 95fc87b441 ("vfio: Selective dirty page tracking if IOMMU backed device pins pages")
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Added a check such that only singleton IOMMU groups can pin pages.
>From the point when vendor driver pins any pages, consider IOMMU group
dirty page scope to be limited to pinned pages.
To optimize to avoid walking list often, added flag
pinned_page_dirty_scope to indicate if all of the vfio_groups for each
vfio_domain in the domain_list dirty page scope is limited to pinned
pages. This flag is updated on first pinned pages request for that IOMMU
group and on attaching/detaching group.
Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Neo Jia <cjia@nvidia.com>
Reviewed-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Allow bus drivers to provide their own callback to match a device to
the user provided string.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
vfio_group_pin_pages() and vfio_group_unpin_pages() are introduced to
avoid inefficient search/check/ref/deref opertions associated with VFIO
group as those in each calling into vfio_pin_pages() and
vfio_unpin_pages().
VFIO group is taken as arg directly. The callers combine
search/check/ref/deref operations associated with VFIO group by calling
vfio_group_get_external_user()/vfio_group_get_external_user_from_dev()
beforehand, and vfio_group_put_external_user() afterwards.
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
vfio_dma_rw will read/write a range of user space memory pointed to by
IOVA into/from a kernel buffer without enforcing pinning the user space
memory.
TODO: mark the IOVAs to user space memory dirty if they are written in
vfio_dma_rw().
Cc: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
external user calls vfio_group_get_external_user_from_dev() with a device
pointer to get the VFIO group associated with this device.
The VFIO group is checked to be vialbe and have IOMMU set. Then
container user counter is increased and VFIO group reference is hold
to prevent the VFIO group from disposal before external user exits.
when the external user finishes using of the VFIO group, it calls
vfio_group_put_external_user() to dereference the VFIO group and the
container user counter.
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Yan Zhao <yan.y.zhao@intel.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Each of these drivers has a copy of the same trivial helper function to
convert the pointer argument and then call the native ioctl handler.
We now have a generic implementation of that, so use it.
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
Reviewed-by: Jiri Kosina <jkosina@suse.cz>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Based on 2 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license version 2 as
published by the free software foundation #
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-only
has been chosen to replace the boilerplate/reference in 4122 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190604081206.933168790@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
vfio_dev_present() which is the condition to
wait_event_interruptible_timeout(), will call vfio_group_get_device
and try to acquire the mutex group->device_lock.
wait_event_interruptible_timeout() will set the state of the current
task to TASK_INTERRUPTIBLE, before doing the condition check. This
means that we will try to acquire the mutex while already in a
sleeping state. The scheduler warns us by giving the following
warning:
[ 4050.264464] ------------[ cut here ]------------
[ 4050.264508] do not call blocking ops when !TASK_RUNNING; state=1 set at [<00000000b33c00e2>] prepare_to_wait_event+0x14a/0x188
[ 4050.264529] WARNING: CPU: 12 PID: 35924 at kernel/sched/core.c:6112 __might_sleep+0x76/0x90
....
4050.264756] Call Trace:
[ 4050.264765] ([<000000000017bbaa>] __might_sleep+0x72/0x90)
[ 4050.264774] [<0000000000b97edc>] __mutex_lock+0x44/0x8c0
[ 4050.264782] [<0000000000b9878a>] mutex_lock_nested+0x32/0x40
[ 4050.264793] [<000003ff800d7abe>] vfio_group_get_device+0x36/0xa8 [vfio]
[ 4050.264803] [<000003ff800d87c0>] vfio_del_group_dev+0x238/0x378 [vfio]
[ 4050.264813] [<000003ff8015f67c>] mdev_remove+0x3c/0x68 [mdev]
[ 4050.264825] [<00000000008e01b0>] device_release_driver_internal+0x168/0x268
[ 4050.264834] [<00000000008de692>] bus_remove_device+0x162/0x190
[ 4050.264843] [<00000000008daf42>] device_del+0x1e2/0x368
[ 4050.264851] [<00000000008db12c>] device_unregister+0x64/0x88
[ 4050.264862] [<000003ff8015ed84>] mdev_device_remove+0xec/0x130 [mdev]
[ 4050.264872] [<000003ff8015f074>] remove_store+0x6c/0xa8 [mdev]
[ 4050.264881] [<000000000046f494>] kernfs_fop_write+0x14c/0x1f8
[ 4050.264890] [<00000000003c1530>] __vfs_write+0x38/0x1a8
[ 4050.264899] [<00000000003c187c>] vfs_write+0xb4/0x198
[ 4050.264908] [<00000000003c1af2>] ksys_write+0x5a/0xb0
[ 4050.264916] [<0000000000b9e270>] system_call+0xdc/0x2d8
[ 4050.264925] 4 locks held by sh/35924:
[ 4050.264933] #0: 000000001ef90325 (sb_writers#4){.+.+}, at: vfs_write+0x9e/0x198
[ 4050.264948] #1: 000000005c1ab0b3 (&of->mutex){+.+.}, at: kernfs_fop_write+0x1cc/0x1f8
[ 4050.264963] #2: 0000000034831ab8 (kn->count#297){++++}, at: kernfs_remove_self+0x12e/0x150
[ 4050.264979] #3: 00000000e152484f (&dev->mutex){....}, at: device_release_driver_internal+0x5c/0x268
[ 4050.264993] Last Breaking-Event-Address:
[ 4050.265002] [<000000000017bbaa>] __might_sleep+0x72/0x90
[ 4050.265010] irq event stamp: 7039
[ 4050.265020] hardirqs last enabled at (7047): [<00000000001cee7a>] console_unlock+0x6d2/0x740
[ 4050.265029] hardirqs last disabled at (7054): [<00000000001ce87e>] console_unlock+0xd6/0x740
[ 4050.265040] softirqs last enabled at (6416): [<0000000000b8fe26>] __udelay+0xb6/0x100
[ 4050.265049] softirqs last disabled at (6415): [<0000000000b8fe06>] __udelay+0x96/0x100
[ 4050.265057] ---[ end trace d04a07d39d99a9f9 ]---
Let's fix this as described in the article
https://lwn.net/Articles/628628/.
Signed-off-by: Farhan Ali <alifm@linux.ibm.com>
[remove now redundant vfio_dev_present()]
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Use dev_printk() when possible to make messages consistent with other
device-related messages.
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Actually, total amount of available minor number
for a single major is MINORMARK + 1. So expand
minor range when registering chrdev region.
Signed-off-by: Chengguang Xu <cgxu519@gmx.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
match_string() returns the index of an array for a matching string,
which can be used intead of open coded variant.
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: kvm@vger.kernel.org
Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
The vfio_info_add_capability() helper requires the caller to pass a
capability ID, which it then uses to fill in header fields, assuming
hard coded versions. This makes for an awkward and rigid interface.
The only thing we want this helper to do is allocate sufficient
space in the caps buffer and chain this capability into the list.
Reduce it to that simple task.
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Please do not apply this to mainline directly, instead please re-run the
coccinelle script shown below and apply its output.
For several reasons, it is desirable to use {READ,WRITE}_ONCE() in
preference to ACCESS_ONCE(), and new code is expected to use one of the
former. So far, there's been no reason to change most existing uses of
ACCESS_ONCE(), as these aren't harmful, and changing them results in
churn.
However, for some features, the read/write distinction is critical to
correct operation. To distinguish these cases, separate read/write
accessors must be used. This patch migrates (most) remaining
ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following
coccinelle script:
----
// Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and
// WRITE_ONCE()
// $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch
virtual patch
@ depends on patch @
expression E1, E2;
@@
- ACCESS_ONCE(E1) = E2
+ WRITE_ONCE(E1, E2)
@ depends on patch @
expression E;
@@
- ACCESS_ONCE(E)
+ READ_ONCE(E)
----
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: davem@davemloft.net
Cc: linux-arch@vger.kernel.org
Cc: mpe@ellerman.id.au
Cc: shuah@kernel.org
Cc: snitzer@redhat.com
Cc: thor.thayer@linux.intel.com
Cc: tj@kernel.org
Cc: viro@zeniv.linux.org.uk
Cc: will.deacon@arm.com
Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
When the user unbinds the last device of a group from a vfio bus
driver, the devices within that group should be available for other
purposes. We currently have a race that makes this generally, but
not always true. The device can be unbound from the vfio bus driver,
but remaining IOMMU context of the group attached to the container
can result in errors as the next driver configures DMA for the device.
Wait for the group to be detached from the IOMMU backend before
allowing the bus driver remove callback to complete.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
In vfio_iommu_group_get() we want to increase the reference
count of the iommu group.
In noiommu case, the group does not exist and is allocated.
iommu_group_add_device() increases the group ref count. However we
then call iommu_group_put() which decrements it.
This leads to a "refcount_t: underflow WARN_ON".
Only decrement the ref count in case of iommu_group_add_device
failure.
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
