15d2aba7c6
The Interrupt Message Number in the PCIe Capabilities register (PCIe r4.0,
sec 7.5.3.2) indicates which MSI/MSI-X vector is shared by interrupts
related to the PCIe Capability, including Link Bandwidth Management and
Link Autonomous Bandwidth Interrupts (Link Control, 7.5.3.7), Command
Completed and Hot-Plug Interrupts (Slot Control, 7.5.3.10), and the PME
Interrupt (Root Control, 7.5.3.12).
pcie_message_numbers() checked whether we want to enable PME or Hot-Plug
interrupts but neglected to check for Link Bandwidth Management, so if we
only wanted the Bandwidth Management interrupts, it decided we didn't need
any vectors at all. Then pcie_port_enable_irq_vec() tried to reallocate
zero vectors, which failed, resulting in fallback to INTx.
On some systems, e.g., an X79-based workstation, that INTx seems broken or
not handled correctly, so we got spurious IRQ16 interrupts for Bandwidth
Management events.
Change pcie_message_numbers() so that if we want Link Bandwidth Management
interrupts, we use the shared MSI/MSI-X vector from the PCIe Capabilities
register.
Fixes: e8303bb7a75c ("PCI/LINK: Report degraded links via link bandwidth notification")
Link: https://lore.kernel.org/lkml/155597243666.19387.1205950870601742062.stgit@gimli.home
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
[bhelgaas: changelog]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.