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PCI/portdrv: Use shared MSI/MSI-X vector for Bandwidth Management 

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: e8303bb7a7 ("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>
This commit is contained in:
Alex Williamson 2019-04-22 16:43:30 -06:00 committed by Bjorn Helgaas
parent d5bc73f34c
commit 15d2aba7c6
1 changed files with 2 additions and 1 deletions
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3
drivers/pci/pcie/portdrv_core.c
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@ -55,7 +55,8 @@ static int pcie_message_numbers(struct pci_dev *dev, int mask,
* 7.8.2, 7.10.10, 7.31.2.
*/
if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP)) {
if (mask & (PCIE_PORT_SERVICE_PME | PCIE_PORT_SERVICE_HP |
PCIE_PORT_SERVICE_BWNOTIF)) {
pcie_capability_read_word(dev, PCI_EXP_FLAGS, &reg16);
*pme = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9;
nvec = *pme + 1;