Re: [PATCH V10 vfio 0/9] Introduce a vfio driver over virtio devices

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On Tue, Dec 19, 2023 at 10:14:52AM -0700, Alex Williamson wrote:
> On Tue, 19 Dec 2023 11:32:38 +0200
> Yishai Hadas <yishaih@xxxxxxxxxx> wrote:
> 
> > This series 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.
> > --------------------------------------------------------------------
> > 
> > The first 6 patches are in the virtio area and handle the below:
> > - Introduce the admin virtqueue infrastcture.
> > - Expose the layout of the commands that should be used for
> >   supporting the legacy access.
> > - Expose APIs to enable upper layers as of vfio, net, etc
> >   to execute admin commands.
> > 
> > The above follows the virtio spec that was lastly accepted in that area
> > [1].
> > 
> > The last 3 patches are in the vfio area and handle the below:
> > - Expose some APIs from vfio/pci to be used by the vfio/virtio driver.
> > - Introduce a vfio driver over virtio devices to support the legacy
> >   interface functionality for VFs. 
> > 
> > The series was tested successfully over virtio-net VFs in the host,
> > while running in the guest both modern and legacy drivers.
> > 
> > [1]
> > https://github.com/oasis-tcs/virtio-spec/commit/03c2d32e5093ca9f2a17797242fbef88efe94b8c
> > 
> > Changes from V9: https://lore.kernel.org/kvm/20231218083755.96281-1-yishaih@xxxxxxxxxx/
> > Virtio:
> > - Introduce a new config option VIRTIO_PCI_ADMIN_LEGACY which considers X86 or
> >   COMPILE_TEST, then use it instead of CONFIG_X86.
> > Vfio:
> > Patch #9:
> > - Change Kconfig to depend on VIRTIO_PCI_ADMIN_LEGACY.
> > - Drop a redundant blank line at the end of Makefile.
> > 
> > The above changes were suggested by Alex.
> > 
> > Changes from V8: https://lore.kernel.org/kvm/20231214123808.76664-1-yishaih@xxxxxxxxxx/
> > Virtio:
> > - Adapt to support the legacy IO functionality only on X86, as
> >   was suggested by Michael.
> > Vfio:
> > Patch #9:
> > - Change Kconfig to depend on X86, as suggested by Alex. 
> > - Add Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>.
> > 
> > Changes from V7: https://lore.kernel.org/kvm/20231207102820.74820-1-yishaih@xxxxxxxxxx/
> > Virtio:
> > Patch #6
> > - Let virtio_pci_admin_has_legacy_io() return false on non X86 systems,
> >   as was discussed with Michael.
> > Vfio:
> > Patch #7, #8:
> > - Add Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
> > Patch #9:
> > - Improve the Kconfig description and the commit log, as was suggested by Kevin.
> > - Rename translate_io_bar_to_mem_bar() to virtiovf_pci_bar0_rw(), as
> >   was suggested by Kevin.
> > - Refactor to have virtiovf_pci_write_config() as we have
> >   virtiovf_pci_read_config(), as was suggested by Kevin.
> > - Drop a note about MSIX which doesn't give any real value, as was
> >   suggested by Kevin.
> > 
> > Changes from V6: https://lore.kernel.org/kvm/20231206083857.241946-1-yishaih@xxxxxxxxxx/
> > Vfio:
> > - Put the pm_runtime stuff into translate_io_bar_to_mem_bar() and
> >   organize the callers to be more success oriented, as suggested by Jason.
> > - Add missing 'ops' (i.e. 'detach_ioas' and 'device_feature'), as mentioned by Jason.
> > - Clean virtiovf_bar0_exists() to cast to bool automatically, as
> >   suggested by Jason.
> > - Add Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>.
> > 
> > Changes from V5: https://lore.kernel.org/kvm/20231205170623.197877-1-yishaih@xxxxxxxxxx/
> > Vfio:
> > - Rename vfio_pci_iowrite64 to vfio_pci_core_iowrite64 as was mentioned
> >   by Alex.
> > 
> > Changes from V4: https://lore.kernel.org/all/20231129143746.6153-7-yishaih@xxxxxxxxxx/T/
> > Virtio:
> > - Drop the unused macro 'VIRTIO_ADMIN_MAX_CMD_OPCODE' as was asked by
> >   Michael.
> > - Add Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> > Vfio:
> > - Export vfio_pci_core_setup_barmap() in place and rename
> >   vfio_pci_iowrite/read<xxx> to have the 'core' prefix as part of the
> >   functions names, as was discussed with Alex.
> > - Improve packing of struct virtiovf_pci_core_device, as was suggested
> >   by Alex.
> > - Upon reset, set 'pci_cmd' back to zero, in addition, if
> >   the user didn't set the 'PCI_COMMAND_IO' bit, return -EIO upon any
> >   read/write towards the IO bar, as was suggested by Alex.
> > - Enforce by BUILD_BUG_ON that 'bar0_virtual_buf_size' is power of 2 as
> >   part of virtiovf_pci_init_device() and clean the 'sizing calculation'
> >   code accordingly, as was suggested by Alex.
> > 
> > Changes from V3: https://www.spinics.net/lists/kvm/msg333008.html
> > Virtio:
> > - Rebase on top of 6.7 rc3.
> > Vfio:
> > - Fix a typo, drop 'acc' from 'virtiovf_acc_vfio_pci_tran_ops'.
> > 
> > Changes from V2: https://lore.kernel.org/all/20231029155952.67686-8-yishaih@xxxxxxxxxx/T/
> > Virtio:
> > - Rebase on top of 6.7 rc1.
> > - Add a mutex to serialize admin commands execution and virtqueue
> >   deletion, as was suggested by Michael.
> > - Remove the 'ref_count' usage which is not needed any more.
> > - Reduce the depth of the admin vq to match a single command at a given time.
> > - Add a supported check upon command execution and move to use a single
> >   flow of virtqueue_exec_admin_cmd().
> > - Improve the description of the exported commands to better match the
> >   specification and the expected usage as was asked by Michael.
> > 
> > Vfio:
> > - Upon calling to virtio_pci_admin_legacy/common_device_io_read/write()
> >   supply the 'offset' within the relevant configuration area, following
> >   the virtio exported APIs.
> > 
> > Changes from V1: https://lore.kernel.org/all/20231023104548.07b3aa19.alex.williamson@xxxxxxxxxx/T/
> > Virtio:
> > - Drop its first patch, it was accepted upstream already.
> > - Add a new patch (#6) which initializes the supported admin commands
> >   upon admin queue activation as was suggested by Michael.
> > - Split the legacy_io_read/write commands per common/device
> >   configuration as was asked by Michael.
> > - Don't expose any more the list query/used APIs outside of virtio.
> > - Instead, expose an API to check whether the legacy io functionality is
> >   supported as was suggested by Michael.
> > - Fix some Krobot's note by adding the missing include file.
> > 
> > Vfio:
> > - Refer specifically to virtio-net as part of the driver/module description
> >   as Alex asked.
> > - Change to check MSIX enablement based on the irq type of the given vfio
> >   core device. In addition, drop its capable checking from the probe flow
> >   as was asked by Alex.
> > - Adapt to use the new virtio exposed APIs and clean some code accordingly.
> > - Adapt to some cleaner style code in some places (if/else) as was suggested
> >   by Alex.
> > - Fix the range_intersect_range() function and adapt its usage as was
> >   pointed by Alex.
> > - Make struct virtiovf_pci_core_device better packed.
> > - Overwrite the subsystem vendor ID to be 0x1af4 as was discussed in
> >   the ML.
> > - Add support for the 'bar sizing negotiation' as was asked by Alex.
> > - Drop the 'acc' from the 'ops' as Alex asked.
> > 
> > Changes from V0: https://www.spinics.net/lists/linux-virtualization/msg63802.html
> > 
> > Virtio:
> > - Fix the common config map size issue that was reported by Michael
> >   Tsirkin.
> > - Do not use vp_dev->vqs[] array upon vp_del_vqs() as was asked by
> >   Michael, instead skip the AQ specifically.
> > - Move admin vq implementation into virtio_pci_modern.c as was asked by
> >   Michael.
> > - Rename structure virtio_avq to virtio_pci_admin_vq and some extra
> >   corresponding renames.
> > - Remove exported symbols virtio_pci_vf_get_pf_dev(),
> >   virtio_admin_cmd_exec() as now callers are local to the module.
> > - Handle inflight commands as part of the device reset flow.
> > - Introduce APIs per admin command in virtio-pci as was asked by Michael.
> > 
> > Vfio:
> > - Change to use EXPORT_SYMBOL_GPL instead of EXPORT_SYMBOL for
> >   vfio_pci_core_setup_barmap() and vfio_pci_iowrite#xxx() as pointed by
> >   Alex.
> > - Drop the intermediate patch which prepares the commands and calls the
> >   generic virtio admin command API (i.e. virtio_admin_cmd_exec()).
> > - Instead, call directly to the new APIs per admin command that are
> >   exported from Virtio - based on Michael's request.
> > - Enable only virtio-net as part of the pci_device_id table to enforce
> >   upon binding only what is supported as suggested by Alex.
> > - Add support for byte-wise access (read/write) over the device config
> >   region as was asked by Alex.
> > - Consider whether MSIX is practically enabled/disabled to choose the
> >   right opcode upon issuing read/write admin command, as mentioned
> >   by Michael.
> > - Move to use VIRTIO_PCI_CONFIG_OFF instead of adding some new defines
> >   as was suggested by Michael.
> > - Set the '.close_device' op to vfio_pci_core_close_device() as was
> >   pointed by Alex.
> > - Adapt to Vfio multi-line comment style in a few places.
> > - Add virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx in the MAINTAINERS file
> >   to be CCed for the new driver as was suggested by Jason.
> > 
> > Yishai
> > 
> > Feng Liu (4):
> >   virtio: Define feature bit for administration virtqueue
> >   virtio-pci: Introduce admin virtqueue
> >   virtio-pci: Introduce admin command sending function
> >   virtio-pci: Introduce admin commands
> > 
> > Yishai Hadas (5):
> >   virtio-pci: Initialize the supported admin commands
> >   virtio-pci: Introduce APIs to execute legacy IO admin commands
> >   vfio/pci: Expose vfio_pci_core_setup_barmap()
> >   vfio/pci: Expose vfio_pci_core_iowrite/read##size()
> >   vfio/virtio: Introduce a vfio driver over virtio devices
> > 
> >  MAINTAINERS                                 |   7 +
> >  drivers/vfio/pci/Kconfig                    |   2 +
> >  drivers/vfio/pci/Makefile                   |   2 +
> >  drivers/vfio/pci/vfio_pci_rdwr.c            |  57 +-
> >  drivers/vfio/pci/virtio/Kconfig             |  15 +
> >  drivers/vfio/pci/virtio/Makefile            |   3 +
> >  drivers/vfio/pci/virtio/main.c              | 576 ++++++++++++++++++++
> >  drivers/virtio/Kconfig                      |   5 +
> >  drivers/virtio/Makefile                     |   1 +
> >  drivers/virtio/virtio.c                     |  37 +-
> >  drivers/virtio/virtio_pci_admin_legacy_io.c | 244 +++++++++
> >  drivers/virtio/virtio_pci_common.c          |  14 +
> >  drivers/virtio/virtio_pci_common.h          |  42 +-
> >  drivers/virtio/virtio_pci_modern.c          | 259 ++++++++-
> >  drivers/virtio/virtio_pci_modern_dev.c      |  24 +-
> >  include/linux/vfio_pci_core.h               |  20 +
> >  include/linux/virtio.h                      |   8 +
> >  include/linux/virtio_config.h               |   4 +
> >  include/linux/virtio_pci_admin.h            |  23 +
> >  include/linux/virtio_pci_modern.h           |   2 +
> >  include/uapi/linux/virtio_config.h          |   8 +-
> >  include/uapi/linux/virtio_pci.h             |  68 +++
> >  22 files changed, 1385 insertions(+), 36 deletions(-)
> >  create mode 100644 drivers/vfio/pci/virtio/Kconfig
> >  create mode 100644 drivers/vfio/pci/virtio/Makefile
> >  create mode 100644 drivers/vfio/pci/virtio/main.c
> >  create mode 100644 drivers/virtio/virtio_pci_admin_legacy_io.c
> >  create mode 100644 include/linux/virtio_pci_admin.h
> > 
> 
> The vfio parts look good to me.  I'll merge the last 3 patches in the
> series through the vfio tree once virtio maintainers are satisfied and
> provide a branch or tag to merge the dependencies.  Thanks,
> 
> Alex

You can go ahead and merge the virtio patches too, with my ack:

Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>

These are self contained enough that I don't expect any conflicts.





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