Commit 0e8ae5a6 authored by Jan Kiszka's avatar Jan Kiszka Committed by Bjorn Helgaas
Browse files

PCI/portdrv: Do not setup up IRQs if there are no users 

Avoid registering service IRQs if there is no service that offers them
or no driver to register a handler against them. This saves IRQ vectors
when they are limited (e.g. on x86) and also avoids that spurious events
could hit a missing handler. Such spurious events need to be generated
by the Jailhouse hypervisor for active MSI vectors when enabling or
disabling itself.

Link: https://lore.kernel.org/r/8f9a13ac-8ab1-15ac-06cb-c131b488a36f@siemens.com


Signed-off-by: default avatarJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent e4e737bb

drivers/pci/pcie/portdrv_core.c

+30 −17
Original line number Diff line number Diff line
@@ -166,9 +166,6 @@ static int pcie_init_service_irqs(struct pci_dev *dev, int *irqs, int mask) 
{

	int ret, i;



	for (i = 0; i < PCIE_PORT_DEVICE_MAXSERVICES; i++)

		irqs[i] = -1;



	/*

	 * If we support PME but can't use MSI/MSI-X for it, we have to

	 * fall back to INTx or other interrupts, e.g., a system shared
@@ -317,8 +314,10 @@ static int pcie_device_init(struct pci_dev *pdev, int service, int irq) 
 */

int pcie_port_device_register(struct pci_dev *dev)

{

	int status, capabilities, i, nr_service;

	int irqs[PCIE_PORT_DEVICE_MAXSERVICES];

	int status, capabilities, irq_services, i, nr_service;

	int irqs[PCIE_PORT_DEVICE_MAXSERVICES] = {

		[0 ... PCIE_PORT_DEVICE_MAXSERVICES-1] = -1

	};



	/* Enable PCI Express port device */

	status = pci_enable_device(dev);
@@ -331,19 +330,33 @@ int pcie_port_device_register(struct pci_dev *dev) 
		return 0;



	pci_set_master(dev);



	irq_services = 0;

	if (IS_ENABLED(CONFIG_PCIE_PME))

		irq_services |= PCIE_PORT_SERVICE_PME;

	if (IS_ENABLED(CONFIG_PCIEAER))

		irq_services |= PCIE_PORT_SERVICE_AER;

	if (IS_ENABLED(CONFIG_HOTPLUG_PCI_PCIE))

		irq_services |= PCIE_PORT_SERVICE_HP;

	if (IS_ENABLED(CONFIG_PCIE_DPC))

		irq_services |= PCIE_PORT_SERVICE_DPC;

	irq_services &= capabilities;



	if (irq_services) {

		/*

	 * Initialize service irqs. Don't use service devices that

		 * Initialize service IRQs. Don't use service devices that

		 * require interrupts if there is no way to generate them.

	 * However, some drivers may have a polling mode (e.g. pciehp_poll_mode)

	 * that can be used in the absence of irqs.  Allow them to determine

	 * if that is to be used.

		 * However, some drivers may have a polling mode (e.g.

		 * pciehp_poll_mode) that can be used in the absence of IRQs.

		 * Allow them to determine if that is to be used.

		 */

	status = pcie_init_service_irqs(dev, irqs, capabilities);

		status = pcie_init_service_irqs(dev, irqs, irq_services);

		if (status) {

		capabilities &= PCIE_PORT_SERVICE_HP;

		if (!capabilities)

			irq_services &= PCIE_PORT_SERVICE_HP;

			if (!irq_services)

				goto error_disable;

		}

	}



	/* Allocate child services if any */

	status = -ENODEV;