mirror of https://gitee.com/openkylin/linux.git
11 Commits
| Author | SHA1 | Message | Date |
|---|---|---|---|
Parav Pandit
|
5715c4dd66 |
vfio/mdev: Synchronize device create/remove with parent removal
In following sequences, child devices created while removing mdev parent
device can be left out, or it may lead to race of removing half
initialized child mdev devices.
issue-1:
--------
cpu-0 cpu-1
----- -----
mdev_unregister_device()
device_for_each_child()
mdev_device_remove_cb()
mdev_device_remove()
create_store()
mdev_device_create() [...]
device_add()
parent_remove_sysfs_files()
/* BUG: device added by cpu-0
* whose parent is getting removed
* and it won't process this mdev.
*/
issue-2:
--------
Below crash is observed when user initiated remove is in progress
and mdev_unregister_driver() completes parent unregistration.
cpu-0 cpu-1
----- -----
remove_store()
mdev_device_remove()
active = false;
mdev_unregister_device()
parent device removed.
[...]
parents->ops->remove()
/*
* BUG: Accessing invalid parent.
*/
This is similar race like create() racing with mdev_unregister_device().
BUG: unable to handle kernel paging request at ffffffffc0585668
PGD e8f618067 P4D e8f618067 PUD e8f61a067 PMD 85adca067 PTE 0
Oops: 0000 [#1] SMP PTI
CPU: 41 PID: 37403 Comm: bash Kdump: loaded Not tainted 5.1.0-rc6-vdevbus+ #6
Hardware name: Supermicro SYS-6028U-TR4+/X10DRU-i+, BIOS 2.0b 08/09/2016
RIP: 0010:mdev_device_remove+0xfa/0x140 [mdev]
Call Trace:
remove_store+0x71/0x90 [mdev]
kernfs_fop_write+0x113/0x1a0
vfs_write+0xad/0x1b0
ksys_write+0x5a/0xe0
do_syscall_64+0x5a/0x210
entry_SYSCALL_64_after_hwframe+0x49/0xbe
Therefore, mdev core is improved as below to overcome above issues.
Wait for any ongoing mdev create() and remove() to finish before
unregistering parent device.
This continues to allow multiple create and remove to progress in
parallel for different mdev devices as most common case.
At the same time guard parent removal while parent is being accessed by
create() and remove() callbacks.
create()/remove() and unregister_device() are synchronized by the rwsem.
Refactor device removal code to mdev_device_remove_common() to avoid
acquiring unreg_sem of the parent.
Fixes:
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Parav Pandit
|
522ecce08a |
vfio/mdev: Improve the create/remove sequence
This patch addresses below two issues and prepares the code to address
3rd issue listed below.
1. mdev device is placed on the mdev bus before it is created in the
vendor driver. Once a device is placed on the mdev bus without creating
its supporting underlying vendor device, mdev driver's probe() gets
triggered. However there isn't a stable mdev available to work on.
create_store()
mdev_create_device()
device_register()
...
vfio_mdev_probe()
[...]
parent->ops->create()
vfio_ap_mdev_create()
mdev_set_drvdata(mdev, matrix_mdev);
/* Valid pointer set above */
Due to this way of initialization, mdev driver who wants to use the mdev,
doesn't have a valid mdev to work on.
2. Current creation sequence is,
parent->ops_create()
groups_register()
Remove sequence is,
parent->ops->remove()
groups_unregister()
However, remove sequence should be exact mirror of creation sequence.
Once this is achieved, all users of the mdev will be terminated first
before removing underlying vendor device.
(Follow standard linux driver model).
At that point vendor's remove() ops shouldn't fail because taking the
device off the bus should terminate any usage.
3. When remove operation fails, mdev sysfs removal attempts to add the
file back on already removed device. Following call trace [1] is observed.
[1] call trace:
kernel: WARNING: CPU: 2 PID: 9348 at fs/sysfs/file.c:327 sysfs_create_file_ns+0x7f/0x90
kernel: CPU: 2 PID: 9348 Comm: bash Kdump: loaded Not tainted 5.1.0-rc6-vdevbus+ #6
kernel: Hardware name: Supermicro SYS-6028U-TR4+/X10DRU-i+, BIOS 2.0b 08/09/2016
kernel: RIP: 0010:sysfs_create_file_ns+0x7f/0x90
kernel: Call Trace:
kernel: remove_store+0xdc/0x100 [mdev]
kernel: kernfs_fop_write+0x113/0x1a0
kernel: vfs_write+0xad/0x1b0
kernel: ksys_write+0x5a/0xe0
kernel: do_syscall_64+0x5a/0x210
kernel: entry_SYSCALL_64_after_hwframe+0x49/0xbe
Therefore, mdev core is improved in following ways.
1. Split the device registration/deregistration sequence so that some
things can be done between initialization of the device and hooking it
up to the bus respectively after deregistering it from the bus but
before giving up our final reference.
In particular, this means invoking the ->create() and ->remove()
callbacks in those new windows. This gives the vendor driver an
initialized mdev device to work with during creation.
At the same time, a bus driver who wish to bind to mdev driver also
gets initialized mdev device.
This follows standard Linux kernel bus and device model.
2. During remove flow, first remove the device from the bus. This
ensures that any bus specific devices are removed.
Once device is taken off the mdev bus, invoke remove() of mdev
from the vendor driver.
3. The driver core device model provides way to register and auto
unregister the device sysfs attribute groups at dev->groups.
Make use of dev->groups to let core create the groups and eliminate
code to avoid explicit groups creation and removal.
To ensure, that new sequence is solid, a below stack dump of a
process is taken who attempts to remove the device while device is in
use by vfio driver and user application.
This stack dump validates that vfio driver guards against such device
removal when device is in use.
cat /proc/21962/stack
[<0>] vfio_del_group_dev+0x216/0x3c0 [vfio]
[<0>] mdev_remove+0x21/0x40 [mdev]
[<0>] device_release_driver_internal+0xe8/0x1b0
[<0>] bus_remove_device+0xf9/0x170
[<0>] device_del+0x168/0x350
[<0>] mdev_device_remove_common+0x1d/0x50 [mdev]
[<0>] mdev_device_remove+0x8c/0xd0 [mdev]
[<0>] remove_store+0x71/0x90 [mdev]
[<0>] kernfs_fop_write+0x113/0x1a0
[<0>] vfs_write+0xad/0x1b0
[<0>] ksys_write+0x5a/0xe0
[<0>] do_syscall_64+0x5a/0x210
[<0>] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[<0>] 0xffffffffffffffff
This prepares the code to eliminate calling device_create_file() in
subsequent patch.
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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Linus Torvalds
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a13f065550 |
IOMMU Updates for Linux v5.2
Including: - ATS support for ARM-SMMU-v3. - AUX domain support in the IOMMU-API and the Intel VT-d driver. This adds support for multiple DMA address spaces per (PCI-)device. The use-case is to multiplex devices between host and KVM guests in a more flexible way than supported by SR-IOV. - The Rest are smaller cleanups and fixes, two of which needed to be reverted after testing in linux-next. -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEr9jSbILcajRFYWYyK/BELZcBGuMFAlzZWPkACgkQK/BELZcB GuPdRRAAj/RcgVn7fqmNDM02xe6C5PuwBGYkXnC+atDrTQWbFsM0JE3YTWEHJ+66 7RMoYaksRaSBsn3QuX3b6+g6E+exhGoQ0BfkmuF8StUXAsaxvzGxvuk+cP0o4/mK pZkj3BddS4ycRqQPsVEbgJGRzL39dxWHe7p3/FfwgV+HzVonURFozU0HixLAoBhr uS0LpBiG8uGCMvO6yhTmPmfrbsSAcMivb7LlmsaykXPhjBk7kSqNgHNNx5O+HC8m XJdFatkxolkrN6A2FoHdP05sAXCv+uHbAGGGitYziRaXG7GBzm7Vc2LspJIml+y2 898+MiTH1M3P0WPyDa3cfcnRc2BBuJg56emad4CcfduM9sVXI0Ol6slNAYljnSYD 5A0CUxbrLxGUZaf6DAUJ9w5L+LhgEkXzKWEE9Nif46K4I1CFSt/d8nwB6Q5Oc/ie GZwTICRkMwTeqOM/CTyvwJCCwZm47AVv3qwaI0z5oDplH/bbRmNEi5WFJsgcgOnd GS5kmzjFBsljjDVWswgugdm7sdMSl7y88uQK9zUiG8fXgRiVUW/rENfZ1SMmVl1p zBQDndZmtrHm5ybe/NAZ8vaJhk4i1F3rWT0hwRZZKGDIrd/C3egnNyYkc4XeTPGe 3il+dJleIIwOX5Fpa44XTV1rDuVOXpF5LS5NRLjhhd+XqbaXZFI= =HLtu -----END PGP SIGNATURE----- Merge tag 'iommu-updates-v5.2' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/joro/iommu Pull IOMMU updates from Joerg Roedel: - ATS support for ARM-SMMU-v3. - AUX domain support in the IOMMU-API and the Intel VT-d driver. This adds support for multiple DMA address spaces per (PCI-)device. The use-case is to multiplex devices between host and KVM guests in a more flexible way than supported by SR-IOV. - the rest are smaller cleanups and fixes, two of which needed to be reverted after testing in linux-next. * tag 'iommu-updates-v5.2' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (45 commits) Revert "iommu/amd: Flush not present cache in iommu_map_page" Revert "iommu/amd: Remove the leftover of bypass support" iommu/vt-d: Fix leak in intel_pasid_alloc_table on error path iommu/vt-d: Make kernel parameter igfx_off work with vIOMMU iommu/vt-d: Set intel_iommu_gfx_mapped correctly iommu/amd: Flush not present cache in iommu_map_page iommu/vt-d: Cleanup: no spaces at the start of a line iommu/vt-d: Don't request page request irq under dmar_global_lock iommu/vt-d: Use struct_size() helper iommu/mediatek: Fix leaked of_node references iommu/amd: Remove amd_iommu_pd_list iommu/arm-smmu: Log CBFRSYNRA register on context fault iommu/arm-smmu-v3: Don't disable SMMU in kdump kernel iommu/arm-smmu-v3: Disable tagged pointers iommu/arm-smmu-v3: Add support for PCI ATS iommu/arm-smmu-v3: Link domains and devices iommu/arm-smmu-v3: Add a master->domain pointer iommu/arm-smmu-v3: Store SteamIDs in master iommu/arm-smmu-v3: Rename arm_smmu_master_data to arm_smmu_master ACPI/IORT: Check ATS capability in root complex nodes ... |
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Parav Pandit
|
f707d837b6 |
vfio/mdev: Removed unused kref
Remove unused kref from the mdev_device structure.
Fixes:
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Lu Baolu
|
8ac13175cb |
vfio/mdev: Add iommu related member in mdev_device
A parent device might create different types of mediated
devices. For example, a mediated device could be created
by the parent device with full isolation and protection
provided by the IOMMU. One usage case could be found on
Intel platforms where a mediated device is an assignable
subset of a PCI, the DMA requests on behalf of it are all
tagged with a PASID. Since IOMMU supports PASID-granular
translations (scalable mode in VT-d 3.0), this mediated
device could be individually protected and isolated by an
IOMMU.
This patch adds a new member in the struct mdev_device to
indicate that the mediated device represented by mdev could
be isolated and protected by attaching a domain to a device
represented by mdev->iommu_device. It also adds a helper to
add or set the iommu device.
* mdev_device->iommu_device
- This, if set, indicates that the mediated device could
be fully isolated and protected by IOMMU via attaching
an iommu domain to this device. If empty, it indicates
using vendor defined isolation, hence bypass IOMMU.
* mdev_set/get_iommu_device(dev, iommu_device)
- Set or get the iommu device which represents this mdev
in IOMMU's device scope. Drivers don't need to set the
iommu device if it uses vendor defined isolation.
Cc: Ashok Raj <ashok.raj@intel.com>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Liu Yi L <yi.l.liu@intel.com>
Suggested-by: Kevin Tian <kevin.tian@intel.com>
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Reviewed-by: Kirti Wankhede <kwankhede@nvidia.com>
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Andy Shevchenko
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278bca7f31 |
vfio-mdev: Switch to use new generic UUID API
There are new types and helpers that are supposed to be used in new code. As a preparation to get rid of legacy types and API functions do the conversion here. Cc: Kirti Wankhede <kwankhede@nvidia.com> Cc: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> |
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Alex Williamson
|
002fe996f6 |
vfio/mdev: Check globally for duplicate devices
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> |
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Alex Williamson
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99e3123e3d |
vfio-mdev: Make mdev_device private and abstract interfaces
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 <zhenyuw@linux.intel.com> Cc: Zhi Wang <zhi.a.wang@intel.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Jike Song <jike.song@intel.com> Reviewed by: Kirti Wankhede <kwankhede@nvidia.com> |
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Alex Williamson
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9372e6feaa |
vfio-mdev: Make mdev_parent private
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> |
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Alex Williamson
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42930553a7 |
vfio-mdev: de-polute the namespace, rename parent_device & parent_ops
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> |
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Kirti Wankhede
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7b96953bc6 |
vfio: Mediated device Core driver
Design for Mediated Device Driver:
Main purpose of this driver is to provide a common interface for mediated
device management that can be used by different drivers of different
devices.
This module provides a generic interface to create the device, add it to
mediated bus, add device to IOMMU group and then add it 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() +--------------+
| | | +<------------------------+ __init() |
| | mdev | | | |
| | bus | +------------------------>+ |<-> VFIO user
| | driver | | probe()/remove() | vfio_mdev.ko | APIs
| | | | | |
| +-----------+ | +--------------+
| |
| MDEV CORE |
| MODULE |
| mdev.ko |
| +-----------+ | mdev_register_device() +--------------+
| | | +<------------------------+ |
| | | | | nvidia.ko |<-> physical
| | | +------------------------>+ | device
| | | | callback +--------------+
| | Physical | |
| | device | | mdev_register_device() +--------------+
| | interface | |<------------------------+ |
| | | | | i915.ko |<-> physical
| | | +------------------------>+ | device
| | | | callback +--------------+
| | | |
| | | | mdev_register_device() +--------------+
| | | +<------------------------+ |
| | | | | ccw_device.ko|<-> physical
| | | +------------------------>+ | device
| | | | callback +--------------+
| +-----------+ |
+---------------+
Core driver provides two types of registration interfaces:
1. Registration interface for mediated bus driver:
/**
* struct mdev_driver - 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 device should use this interface to register
and unregister with core driver respectively:
int mdev_register_driver(struct mdev_driver *drv, struct module *owner);
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 provides vendor driver the set 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_type_groups: attributes to define supported type. This is
mandatory field.
* create: to allocate basic resources in vendor driver for a mediated
device. This is mandatory to be provided by vendor driver.
* remove: to free resources in vendor driver when mediated device is
destroyed. This is mandatory to be provided by vendor driver.
* open: open callback of mediated device
* release: release callback of mediated device
* read : read emulation callback.
* write: write emulation callback.
* ioctl: ioctl callback.
* mmap: mmap emulation callback.
Drivers should use these interfaces 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);
There are no locks to serialize above callbacks in mdev driver and
vfio_mdev driver. If required, vendor driver can have locks to serialize
above APIs in their driver.
Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
Signed-off-by: Neo Jia <cjia@nvidia.com>
Reviewed-by: Jike Song <jike.song@intel.com>
Reviewed-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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