[patch 00/10] genirq/msi, PCI/MSI: Support for dynamic MSI-X vector expansion - Part 4

Thomas Gleixner
2021-11-27T01:34:01Z

This is finally the point where dynamically expanding MSI-X vectors after
enabling MSI-X is implemented.

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

https://lore.kernel.org/r/20211126222700.862407977@linutronix.de
https://lore.kernel.org/r/20211126224100.303046749@linutronix.de
https://lore.kernel.org/r/20211126230957.239391799@linutronix.de

This last and smallest part of the overall series contains the following
changes:

1) Prepare the core MSI irq domain code to handle range based allocation
and free

2) Prepare the PCI/MSI code to handle range based allocation and free

3) Implement a new interface which allows to expand the MSI-X vector
space after initialization

4) Enable support for the X86 PCI/MSI irq domains

This is unfortunate, but some PCI/MSI irq domain implementations,
e.g. powerpc and the x86/XEN irqdomain wrappers are not really ready
to support this out of the box.

I looked at the 30 places which implement PCI/MSI irq domains and
many of them look like they could support it out of the box, but as
we have two which definitely don't, making this opt-in is the only
safe option.

I've tested this by hacking up the XHCI driver and it works like a charm.

There is certainly some more room for consolidating the PCI/MSI-X usage in
drivers, i.e. getting rid of pci_enable_msix*(), but this would have made
this series even larger and is an orthogonal issue.

The series is based on:

git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v1-part-3

and also available from git:

git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git msi-v1-part-4

Thanks,

tglx
---
arch/powerpc/platforms/pseries/msi.c | 6 +-
arch/x86/kernel/apic/msi.c | 4 -
arch/x86/pci/xen.c | 10 +--
drivers/base/platform-msi.c | 3 -
drivers/pci/msi/irqdomain.c | 39 ++++++++++----
drivers/pci/msi/msi.c | 97 +++++++++++++++++++++++++++--------
drivers/pci/msi/msi.h | 4 -
include/linux/msi.h | 46 +++++++++++-----
include/linux/pci.h | 13 ++++
kernel/irq/msi.c | 75 +++++++++++++++------------
10 files changed, 208 insertions(+), 89 deletions(-)