From 15d2aba7c602cd9005b20ff011b670547b3882c4 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Mon, 22 Apr 2019 16:43:30 -0600 Subject: [PATCH] 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: 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 [bhelgaas: changelog] Signed-off-by: Bjorn Helgaas --- drivers/pci/pcie/portdrv_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c index 7d04f9d087a6..1b330129089f 100644 --- a/drivers/pci/pcie/portdrv_core.c +++ b/drivers/pci/pcie/portdrv_core.c @@ -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, ®16); *pme = (reg16 & PCI_EXP_FLAGS_IRQ) >> 9; nvec = *pme + 1; -- 2.20.1