- 03 Aug, 2023 2 commits
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Dmitry Torokhov authored
Stop taking kv->lock mutex in kvm_vfio_update_coherency() and instead call it with this mutex held: the callers of the function usually already have it taken (and released) before calling kvm_vfio_update_coherency(). This avoid bouncing the lock up and down. The exception is kvm_vfio_release() where we do not take the lock, but it is being executed when the very last reference to kvm_device is being dropped, so there are no concerns about concurrency. Suggested-by:
Alex Williamson <alex.williamson@redhat.com> Reviewed-by:
Dmitry Torokhov <dmitry.torokhov@gmail.com> Reviewed-by:
Kevin Tian <kevin.tian@intel.com> Link: https://lore.kernel.org/r/20230714224538.404793-2-dmitry.torokhov@gmail.comSigned-off-by:
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Dmitry Torokhov authored
kvm_vfio_group_add() creates kvg instance, links it to kv->group_list, and calls kvm_vfio_file_set_kvm() with kvg->file as an argument after dropping kv->lock. If we race group addition and deletion calls, kvg instance may get freed by the time we get around to calling kvm_vfio_file_set_kvm(). Previous iterations of the code did not reference kvg->file outside of the critical section, but used a temporary variable. Still, they had similar problem of the file reference being owned by kvg structure and potential for kvm_vfio_group_del() dropping it before kvm_vfio_group_add() had a chance to complete. Fix this by moving call to kvm_vfio_file_set_kvm() under the protection of kv->lock. We already call it while holding the same lock when vfio group is being deleted, so it should be safe here as well. Fixes: 2fc1bec1 ("kvm: set/clear kvm to/from vfio_group when group add/delete") Reviewed-by:
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- 25 Jul, 2023 36 commits
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Yi Liu authored
This gives notes for userspace applications on device cdev usage. Reviewed-by:
Jason Gunthorpe <jgg@nvidia.com> Tested-by:
Yanting Jiang <yanting.jiang@intel.com> Signed-off-by:
Yi Liu <yi.l.liu@intel.com> Link: https://lore.kernel.org/r/20230718135551.6592-27-yi.l.liu@intel.comSigned-off-by:
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Yi Liu authored
vfio_group is not needed for vfio device cdev, so with vfio device cdev introduced, the vfio_group infrastructures can be compiled out if only cdev is needed. Reviewed-by:
Nicolin Chen <nicolinc@nvidia.com> Tested-by:
Matthew Rosato <mjrosato@linux.ibm.com> Tested-by:
Shameer Kolothum <shameerali.kolothum.thodi@huawei.com> Tested-by:
Terrence Xu <terrence.xu@intel.com> Tested-by:
Zhenzhong Duan <zhenzhong.duan@intel.com> Signed-off-by:
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Yi Liu authored
The IOMMU_CAP_CACHE_COHERENCY check only applies to the physical devices that are IOMMU-backed. But it is now in the group code. If want to compile vfio_group infrastructure out, this check needs to be moved out of the group code. Another reason for this change is to fail the device registration for the physical devices that do not have IOMMU if the group code is not compiled as the cdev interface does not support such devices. Suggested-by:
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Yi Liu authored
This adds ioctl for userspace to attach device cdev fd to and detach from IOAS/hw_pagetable managed by iommufd. VFIO_DEVICE_ATTACH_IOMMUFD_PT: attach vfio device to IOAS or hw_pagetable managed by iommufd. Attach can be undo by VFIO_DEVICE_DETACH_IOMMUFD_PT or device fd close. VFIO_DEVICE_DETACH_IOMMUFD_PT: detach vfio device from the current attached IOAS or hw_pagetable managed by iommufd. Reviewed-by: -
Yi Liu authored
This adds ioctl for userspace to bind device cdev fd to iommufd. VFIO_DEVICE_BIND_IOMMUFD: bind device to an iommufd, hence gain DMA control provided by the iommufd. open_device op is called after bind_iommufd op. Tested-by: -
Yi Liu authored
This adds a local variable to store the user pointer cast result from arg. It avoids the repeated casts in the code when more ioctls are added. Reviewed-by:
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Yi Liu authored
It's common to get a reference to the iommufd context from a given file descriptor. So adds an API for it. Existing users of this API are compiled only when IOMMUFD is enabled, so no need to have a stub for the IOMMUFD disabled case. Tested-by:
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Yi Liu authored
This saves some lines when adding the kvm get logic for the vfio_device cdev path. This also renames _vfio_device_get_kvm_safe() to be vfio_device_get_kvm_safe(). Suggested-by:
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Yi Liu authored
This adds cdev support for vfio_device. It allows the user to directly open a vfio device w/o using the legacy container/group interface, as a prerequisite for supporting new iommu features like nested translation and etc. The device fd opened in this manner doesn't have the capability to access the device as the fops open() doesn't open the device until the successful VFIO_DEVICE_BIND_IOMMUFD ioctl which will be added in a later patch. With this patch, devices registered to vfio core would have both the legacy group and the new device interfaces created. - group interface : /dev/vfio/$groupID - device interface: /dev/vfio/devices/vfioX - normal device ("X" is a unique number across vfio devices) For a given device, the user can identify the matching vfioX by searching the vfio-dev folder under the sysfs path of the device. Take PCI device (0000:6a:01.0) as an example, /sys/bus/pci/devices/0000\:6a\:01.0/vfio-dev/vfioX implies the matching vfioX under /dev/vfio/devices/, and vfio-dev/vfioX/dev contains the major:minor number of the matching /dev/vfio/devices/vfioX. The user can get device fd by opening the /dev/vfio/devices/vfioX. The vfio_device cdev logic in this patch: *) __vfio_register_dev() path ends up doing cdev_device_add() for each vfio_device if VFIO_DEVICE_CDEV configured. *) vfio_unregister_group_dev() path does cdev_device_del(); cdev interface does not support noiommu devices, so VFIO only creates the legacy group interface for the physical devices that do not have IOMMU. noiommu users should use the legacy group interface. Reviewed-by: -
Yi Liu authored
device_del() destroys the vfio-dev/vfioX under the sysfs for vfio_device. There is no reason to keep it while the device is going to be unregistered. This movement is also a preparation for adding vfio_device cdev. Kernel should remove the cdev node of the vfio_device to avoid new registration refcount increment while the device is going to be unregistered. Reviewed-by:
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Yi Liu authored
This avoids endless vfio_device refcount increment by userspace, which would keep blocking the vfio_unregister_group_dev(). Reviewed-by:
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Yi Liu authored
This prepares for adding DETACH ioctl for emulated VFIO devices. Reviewed-by:
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Nicolin Chen authored
Previously, the detach routine is only done by the destroy(). And it was called by vfio_iommufd_emulated_unbind() when the device runs close(), so all the mappings in iopt were cleaned in that setup, when the call trace reaches this detach() routine. Now, there's a need of a detach uAPI, meaning that it does not only need a new iommufd_access_detach() API, but also requires access->ops->unmap() call as a cleanup. So add one. However, leaving that unprotected can introduce some potential of a race condition during the pin_/unpin_pages() call, where access->ioas->iopt is getting referenced. So, add an ioas_lock to protect the context of iopt referencings. Also, to allow the iommufd_access_unpin_pages() callback to happen via this unmap() call, add an ioas_unpin pointer, so the unpin routine won't be affected by the "access->ioas = NULL" trick. Reviewed-by:
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Yi Liu authored
This prepares for adding DETACH ioctl for physical VFIO devices. Reviewed-by:
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Yi Liu authored
.bind_iommufd() will generate an ID to represent this bond, which is needed by userspace for further usage. Store devid in vfio_device_file to avoid passing the pointer in multiple places. Reviewed-by:
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Yi Liu authored
This aligns the bind/attach logic with the coming vfio device cdev support. Reviewed-by:
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Yi Liu authored
This moves the noiommu compat validation logic into vfio_df_group_open(). This is more consistent with what will be done in vfio device cdev path. Reviewed-by:
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Yi Liu authored
VFIO group has historically allowed multi-open of the device FD. This was made secure because the "open" was executed via an ioctl to the group FD which is itself only single open. However, no known use of multiple device FDs today. It is kind of a strange thing to do because new device FDs can naturally be created via dup(). When we implement the new device uAPI (only used in cdev path) there is no natural way to allow the device itself from being multi-opened in a secure manner. Without the group FD we cannot prove the security context of the opener. Thus, when moving to the new uAPI we block the ability of opening a device multiple times. Given old group path still allows it we store a vfio_group pointer in struct vfio_device_file to differentiate. Reviewed-by:
Eric Auger <eric.auger@redhat.com> Tested-by:
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Yi Liu authored
This is for counting the devices that are opened via the cdev path. This count is increased and decreased by the cdev path. The group path checks it to achieve exclusion with the cdev path. With this, only one path (group path or cdev path) will claim DMA ownership. This avoids scenarios in which devices within the same group may be opened via different paths. Reviewed-by:
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Yi Liu authored
Allow the vfio_device file to be in a state where the device FD is opened but the device cannot be used by userspace (i.e. its .open_device() hasn't been called). This inbetween state is not used when the device FD is spawned from the group FD, however when we create the device FD directly by opening a cdev it will be opened in the blocked state. The reason for the inbetween state is that userspace only gets a FD but doesn't gain access permission until binding the FD to an iommufd. So in the blocked state, only the bind operation is allowed. Completing bind will allow user to further access the device. This is implemented by adding a flag in struct vfio_device_file to mark the blocked state and using a simple smp_load_acquire() to obtain the flag value and serialize all the device setup with the thread accessing this device. Following this lockless scheme, it can safely handle the device FD unbound->bound but it cannot handle bound->unbound. To allow this we'd need to add a lock on all the vfio ioctls which seems costly. So once device FD is bound, it remains bound until the FD is closed. Suggested-by:
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Yi Liu authored
This avoids passing too much parameters in multiple functions. Per the input parameter change, rename the function to be vfio_df_open/close(). Reviewed-by:
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Yi Liu authored
This defines KVM_DEV_VFIO_FILE* and make alias with KVM_DEV_VFIO_GROUP*. Old userspace uses KVM_DEV_VFIO_GROUP* works as well. Reviewed-by:
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Yi Liu authored
This renames kvm_vfio_group related helpers to prepare for accepting vfio device fd. No functional change is intended. Reviewed-by:
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Yi Liu authored
This makes the vfio file kAPIs to accept vfio device files, also a preparation for vfio device cdev support. For the kvm set with vfio device file, kvm pointer is stored in struct vfio_device_file, and use kvm_ref_lock to protect kvm set and kvm pointer usage within VFIO. This kvm pointer will be set to vfio_device after device file is bound to iommufd in the cdev path. Reviewed-by:
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Yi Liu authored
This prepares for making the below kAPIs to accept both group file and device file instead of only vfio group file. bool vfio_file_enforced_coherent(struct file *file); void vfio_file_set_kvm(struct file *file, struct kvm *kvm); Reviewed-by:
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Yi Liu authored
This is preparation for adding vfio device cdev support. vfio device cdev requires: 1) A per device file memory to store the kvm pointer set by KVM. It will be propagated to vfio_device:kvm after the device cdev file is bound to an iommufd. 2) A mechanism to block device access through device cdev fd before it is bound to an iommufd. To address the above requirements, this adds a per device file structure named vfio_device_file. For now, it's only a wrapper of struct vfio_device pointer. Other fields will be added to this per file structure in future commits. Reviewed-by:
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Yi Liu authored
This is the way user to invoke hot-reset for the devices opened by cdev interface. User should check the flag VFIO_PCI_HOT_RESET_FLAG_DEV_ID_OWNED in the output of VFIO_DEVICE_GET_PCI_HOT_RESET_INFO ioctl before doing hot-reset for cdev devices. Suggested-by:
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Yi Liu authored
This copies the vfio_pci_dependent_device to userspace during looping each affected device for reporting vfio_pci_hot_reset_info. This avoids counting the affected devices and allocating a potential large buffer to store the vfio_pci_dependent_device of all the affected devices before copying them to userspace. Suggested-by:
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Yi Liu authored
This allows VFIO_DEVICE_GET_PCI_HOT_RESET_INFO ioctl use the iommufd_ctx of the cdev device to check the ownership of the other affected devices. When VFIO_DEVICE_GET_PCI_HOT_RESET_INFO is called on an IOMMUFD managed device, the new flag VFIO_PCI_HOT_RESET_FLAG_DEV_ID is reported to indicate the values returned are IOMMUFD devids rather than group IDs as used when accessing vfio devices through the conventional vfio group interface. Additionally the flag VFIO_PCI_HOT_RESET_FLAG_DEV_ID_OWNED will be reported in this mode if all of the devices affected by the hot-reset are owned by either virtue of being directly bound to the same iommufd context as the calling device, or implicitly owned via a shared IOMMU group. Suggested-by:
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Yi Liu authored
There are drivers that need to search vfio_device within a given dev_set. e.g. vfio-pci. So add a helper. vfio_pci_is_device_in_set() now returns -EBUSY in commit a882c16a ("vfio/pci: Change vfio_pci_try_bus_reset() to use the dev_set") where it was trying to preserve the return of vfio_pci_try_zap_and_vma_lock_cb(). However, it makes more sense to return -ENODEV. Suggested-by:
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Yi Liu authored
This can be used to differentiate whether to report group_id or devid in the revised VFIO_DEVICE_GET_PCI_HOT_RESET_INFO ioctl. At this moment, no cdev path yet, so the vfio_device_cdev_opened() helper always returns false. Reviewed-by:
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Yi Liu authored
This is needed by the vfio-pci driver to report affected devices in the hot-reset for a given device. Reviewed-by:
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Yi Liu authored
This adds the helper to check if any device within the given iommu_group has been bound with the iommufd_ctx. This is helpful for the checking on device ownership for the devices which have not been bound but cannot be bound to any other iommufd_ctx as the iommu_group has been bound. Reviewed-by:
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Yi Liu authored
With this reservation, IOMMUFD users can encode the negative IDs for specific purposes. e.g. VFIO needs two reserved values to tell userspace the ID returned is not valid but has other meaning. Reviewed-by:
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Yi Liu authored
This prepares to add another method for hot reset. The major hot reset logic are moved to vfio_pci_ioctl_pci_hot_reset_groups(). No functional change is intended. Suggested-by:
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Yi Liu authored
This suits more on what the code does. Reviewed-by:
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- 23 Jul, 2023 2 commits
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Linus Torvalds authored
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git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-traceLinus Torvalds authored
Pull tracing fixes from Steven Rostedt: - Swapping the ring buffer for snapshotting (for things like irqsoff) can crash if the ring buffer is being resized. Disable swapping when this happens. The missed swap will be reported to the tracer - Report error if the histogram fails to be created due to an error in adding a histogram variable, in event_hist_trigger_parse() - Remove unused declaration of tracing_map_set_field_descr() * tag 'trace-v6.5-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing/histograms: Return an error if we fail to add histogram to hist_vars list ring-buffer: Do not swap cpu_buffer during resize process tracing: Remove unused extern declaration tracing_map_set_field_descr()
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