[V2,00/31] genirq/msi, PCI/MSI: Spring cleaning - Part 3

Message

Thomas Gleixner Dec. 6, 2021, 10:51 p.m. UTC

This is the third part of [PCI]MSI refactoring which aims to provide the
ability of expanding MSI-X vectors after enabling MSI-X.

The first two parts of this work can be found here:

    https://lore.kernel.org/r/[e-mail]
    https://lore.kernel.org/r/[e-mail]

This third part has the following important changes:

   1) Add locking to protect the MSI descriptor storage

      Right now the MSI descriptor storage (linked list) is not protected
      by anything under the assumption that the list is installed before
      use and destroyed after use. As this is about to change there has to
      be protection

   2) A new set of iterators which allow filtering on the state of the
      descriptors namely whether a descriptor is associated to a Linux
      interrupt or not.

      This cleans up a lot of use cases which have to do this filtering
      manually.

   3) A new set of MSI descriptor allocation functions which make the usage
      sites simpler and confine the storage handling to the core code.

      Trivial MSI descriptors (non PCI) are now allocated by the core code
      automatically when the underlying irq domain requests that.

   4) Rework of sysfs handling to prepare for dynamic extension of MSI-X

      The current mechanism which creates the directory and the attributes
      for all MSI descriptors in one go is obviously not suitable for
      dynamic extension. The rework splits the directory creation out and
      lets the MSI interrupt allocation create the per descriptor
      attributes.

   5) Conversion of the MSI descriptor storage to xarray

      The linked list based storage is suboptimal even without dynamic
      expansion as it requires full list walks to get to a specific
      descriptor. With dynamic expansion this gets even more
      convoluted. Xarray is way more suitable and simplifies the
      final goal of dynamic expansion of the MSI-X space.

This third series is based on:

     git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v2-part-2

and also available from git:

     git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v2-part-3

V1 of this series can be found here:

    https://lore.kernel.org/r/[e-mail]

Changes versus V1:

  - Remove the allocation counter patch as it is not required

  - Fix the powerpc fallout - Cedric

  - Fix the CONFIG typo - Niklas

  - Picked up Reviewed/Tested/Acked-by tags as appropriate

As a consequence of the discussion vs. the general direction of these
patches, part 4 is not going to be updated in it's current form.

The assumption that MSI[X] and IMS are mutually exclusive and that IMS is
basically an extension for finer grained splitup of the PCI device does not
hold.

There is a plan to refactor the code further in order to provide the
desired functionality of MSI[X]/IMS which will also gain the dynamic
extension of MSI-X vectors:

      https://lore.kernel.org/r/87o85v3znb.ffs@tglx

Thanks,

	tglx
---
 .clang-format                          |    1 
 arch/powerpc/platforms/4xx/hsta_msi.c  |    7 
 arch/powerpc/platforms/cell/axon_msi.c |    7 
 arch/powerpc/platforms/pasemi/msi.c    |    9 
 arch/powerpc/sysdev/fsl_msi.c          |    8 
 arch/powerpc/sysdev/mpic_u3msi.c       |    9 
 arch/s390/pci/pci_irq.c                |    6 
 arch/x86/pci/xen.c                     |   14 
 drivers/base/core.c                    |    3 
 drivers/base/platform-msi.c            |  110 -----
 drivers/bus/fsl-mc/fsl-mc-msi.c        |   61 --
 drivers/ntb/msi.c                      |   19 
 drivers/pci/controller/pci-hyperv.c    |   15 
 drivers/pci/msi/irqdomain.c            |   11 
 drivers/pci/msi/legacy.c               |   20 
 drivers/pci/msi/msi.c                  |  258 ++++++------
 drivers/pci/xen-pcifront.c             |    2 
 drivers/soc/ti/ti_sci_inta_msi.c       |   77 +--
 include/linux/device.h                 |    4 
 include/linux/msi.h                    |  107 +++--
 include/linux/soc/ti/ti_sci_inta_msi.h |    1 
 kernel/irq/msi.c                       |  700 ++++++++++++++++++++++-----------
 22 files changed, 794 insertions(+), 655 deletions(-)

Comments

Jason Gunthorpe Dec. 9, 2021, 1:01 a.m. UTC | #1

On Mon, Dec 06, 2021 at 11:51:02PM +0100, Thomas Gleixner wrote:
> This is the third part of [PCI]MSI refactoring which aims to provide the
> ability of expanding MSI-X vectors after enabling MSI-X.

I read through this and didn't have any substantive remarks

Reviewed-by: Jason Gunthorpe <[e-mail]>

Jason