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With a functional and tested backend for virtio-block live migration,
add the virtio-block device ID to the pci_device_id table.
Currently, the driver supports legacy IO functionality only for
virtio-net, and it is accounted for in specific parts of the code.
To enforce this limitation, an explicit check for virtio-net, has been
added in virtiovf_support_legacy_io(). Once a backend implements legacy
IO functionality for virtio-block, the necessary support will be added
to the driver, and this additional check should be removed.
The module description was updated accordingly.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20250302162723.82578-1-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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Now that the driver supports live migration, only the legacy IO
functionality depends on config VIRTIO_PCI_ADMIN_LEGACY.
As part of that we introduce a bool configuration option as a sub menu
under the driver's main live migration feature named
VIRTIO_VFIO_PCI_ADMIN_LEGACY, to control the legacy IO functionality.
This will let users configuring the kernel, know which features from the
description might be available in the resulting driver.
As of that, move the legacy IO into a separate file to be compiled only
once CONFIG_VIRTIO_VFIO_PCI_ADMIN_LEGACY was configured and let the live
migration depends only on VIRTIO_PCI.
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20241113115200.209269-8-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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Add support for basic live migration functionality in VFIO over
virtio-net devices, aligned with the virtio device specification 1.4.
This includes the following VFIO features:
VFIO_MIGRATION_STOP_COPY, VFIO_MIGRATION_P2P.
The implementation registers with the VFIO subsystem using vfio_pci_core
and then incorporates the virtio-specific logic for the migration
process.
The migration follows the definitions in uapi/vfio.h and leverages the
virtio VF-to-PF admin queue command channel for execution device parts
related commands.
Additional Notes:
-----------------
The kernel protocol between the source and target devices contains a
header with metadata, including record size, tag, and flags.
The record size allows the target to recognize and read a complete image
from the source before passing the device part data. This adheres to the
virtio device specification, which mandates that partial device parts
cannot be supplied.
The tag and flags serve as placeholders for future extensions of the
kernel protocol between the source and target, ensuring backward and
forward compatibility.
Both the source and target comply with the virtio device specification
by using a device part object with a unique ID as part of the migration
process. Since this resource is limited to a maximum of 255, its
lifecycle is confined to periods with an active live migration flow.
According to the virtio specification, a device has only two modes:
RUNNING and STOPPED. As a result, certain VFIO transitions (i.e.,
RUNNING_P2P->STOP, STOP->RUNNING_P2P) are treated as no-ops. When
transitioning to RUNNING_P2P, the device state is set to STOP, and it
will remain STOPPED until the transition out of RUNNING_P2P->RUNNING, at
which point it returns to RUNNING. During transition to STOP, the virtio
device only stops initiating outgoing requests(e.g. DMA, MSIx, etc.) but
still must accept incoming operations.
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20241113115200.209269-6-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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range_intersect_range determines an overlap between two ranges. If an
overlap, the helper function returns the overlapping offset and size.
The VFIO PCI variant driver emulates the PCI config space BAR offset
registers. These offset may be accessed for read/write with a variety
of lengths including sub-word sizes from sub-word offsets. The driver
makes use of this helper function to read/write the targeted part of
the emulated register.
Make this a vfio_pci_core function, rename and export as GPL. Also
update references in virtio driver.
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Ankit Agrawal <ankita@nvidia.com>
Link: https://lore.kernel.org/r/20240220115055.23546-3-ankita@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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Declare virtiovf_pci_aer_reset_done() as a static function to prevent
the below build warning.
"warning: no previous prototype for 'virtiovf_pci_aer_reset_done'
[-Wmissing-prototypes]"
Fixes: eb61eca0e8c3 ("vfio/virtio: Introduce a vfio driver over virtio devices")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/lkml/20231220143122.63337669@canb.auug.org.au/
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20231220082456.241973-1-yishaih@nvidia.com
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312202115.oDmvN1VE-lkp@intel.com/
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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Introduce a vfio driver over virtio devices to support the legacy
interface functionality for VFs.
Background, from the virtio spec [1].
--------------------------------------------------------------------
In some systems, there is a need to support a virtio legacy driver with
a device that does not directly support the legacy interface. In such
scenarios, a group owner device can provide the legacy interface
functionality for the group member devices. The driver of the owner
device can then access the legacy interface of a member device on behalf
of the legacy member device driver.
For example, with the SR-IOV group type, group members (VFs) can not
present the legacy interface in an I/O BAR in BAR0 as expected by the
legacy pci driver. If the legacy driver is running inside a virtual
machine, the hypervisor executing the virtual machine can present a
virtual device with an I/O BAR in BAR0. The hypervisor intercepts the
legacy driver accesses to this I/O BAR and forwards them to the group
owner device (PF) using group administration commands.
--------------------------------------------------------------------
Specifically, this driver adds support for a virtio-net VF to be exposed
as a transitional device to a guest driver and allows the legacy IO BAR
functionality on top.
This allows a VM which uses a legacy virtio-net driver in the guest to
work transparently over a VF which its driver in the host is that new
driver.
The driver can be extended easily to support some other types of virtio
devices (e.g virtio-blk), by adding in a few places the specific type
properties as was done for virtio-net.
For now, only the virtio-net use case was tested and as such we introduce
the support only for such a device.
Practically,
Upon probing a VF for a virtio-net device, in case its PF supports
legacy access over the virtio admin commands and the VF doesn't have BAR
0, we set some specific 'vfio_device_ops' to be able to simulate in SW a
transitional device with I/O BAR in BAR 0.
The existence of the simulated I/O bar is reported later on by
overwriting the VFIO_DEVICE_GET_REGION_INFO command and the device
exposes itself as a transitional device by overwriting some properties
upon reading its config space.
Once we report the existence of I/O BAR as BAR 0 a legacy driver in the
guest may use it via read/write calls according to the virtio
specification.
Any read/write towards the control parts of the BAR will be captured by
the new driver and will be translated into admin commands towards the
device.
In addition, any data path read/write access (i.e. virtio driver
notifications) will be captured by the driver and forwarded to the
physical BAR which its properties were supplied by the admin command
VIRTIO_ADMIN_CMD_LEGACY_NOTIFY_INFO upon the probing/init flow.
With that code in place a legacy driver in the guest has the look and
feel as if having a transitional device with legacy support for both its
control and data path flows.
[1]
https://github.com/oasis-tcs/virtio-spec/commit/03c2d32e5093ca9f2a17797242fbef88efe94b8c
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/20231219093247.170936-10-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
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