Currently, MSI-X vector enabling and allocation for a PCIe device is static i.e. a device driver gets only one chance to enable a specific number of MSI-X vectors, usually during device probe. Also, in many cases, drivers usually reserve more than required number of vectors anticipating their use, which unnecessarily blocks resources that could have been made available to other devices. Lastly, there is no way for drivers to reserve more vectors, if the MSI-x has already been enabled for that device. Hence, a dynamic MSI-X kernel infrastructure can benefit drivers by deferring MSI-X allocation to post probe phase, where actual demand information is available. This patchset enables the dynamic allocation/de-allocation of MSI-X vectors by introducing 2 new APIs: pci_alloc_irq_vectors_dyn() and pci_free_irq_vectors_grp(): We have had requests from some of the NIC/RDMA users who have lots of interrupt resources and would like to allocate them on demand, instead of using an all or none approach. The APIs are fairly well tested (multiple allocations/deallocations), but we have no early adopters yet. Hence, sending this series as an RFC for review and comments. The patches are based out of Linux 5.2-rc5. Megha Dey (6): PCI/MSI: New structures/macros for dynamic MSI-X allocation PCI/MSI: Dynamic allocation of MSI-X vectors by group x86: Introduce the dynamic teardown function PCI/MSI: Introduce new structure to manage MSI-x entries PCI/MSI: Free MSI-X resources by group Documentation: PCI/MSI: Document dynamic MSI-X infrastructure Documentation/PCI/MSI-HOWTO.txt | 38 +++++ arch/x86/include/asm/x86_init.h | 1 + arch/x86/kernel/x86_init.c | 6 + drivers/pci/msi.c | 363 +++++++++++++++++++++++++++++++++++++--- drivers/pci/probe.c | 9 + include/linux/device.h | 3 + include/linux/msi.h | 13 ++ include/linux/pci.h | 61 +++++++ kernel/irq/msi.c | 34 +++- 9 files changed, 497 insertions(+), 31 deletions(-) -- 2.7.4
